当前期刊: Journal of The Electrochemical Society Go to current issue    加入关注   
显示样式:        排序: 导出
我的关注
我的收藏
您暂时未登录!
登录
  • Towards Ultra Low Cobalt Cathodes: A High Fidelity Computational Phase Search of Layered Li-Ni-Mn-Co Oxides
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2019-12-11
    Gregory Houchins, Venkatasubramanian Viswanathan

    Layered Li(Ni,Mn,Co,)O2 (NMC) presents an intriguing ternary alloy design space for optimization as a cathode material in Li-ion batteries. In the case of NMC, however, only a select few proportions of transition metal cations have been attempted and even fewer have been adopted on a large scale. Recently, the high cost and resource limitations of Co have added a new design constraint and high Ni-containing NMC alloys have gained enormous attention despite possible performance trade-offs. Although the limited collection of NMC cathodes have been successful in providing the performance needed for many applications, specifically electric vehicles, this concern around Co requires further advancement and optimization within the NMC design space. Additionally, it is not fully understood if this material space is a disordered solid solution at room temperature and any arbitrary combination can be used or if there exist distinct transition metal orderings to which meta-stable solid solutions will decay during cycling and affect performance. Here, we present a high fidelity computational search of the ternary phase diagram with an emphasis on high-Ni, and thus low Co, containing compositional phases to understand the room temperature stability of the ordered and disordered solid solution phases. This is done through the use of density functional theory training data fed into a reduced order model Hamiltonian that accounts for effective electronic and spin interactions of neighboring transition metal atoms at various lengths in a background of fixed composition and position lithium and oxygen atoms. This model can then be solved to include finite temperature thermodynamics into a convex hull analysis to understand the regions of ordered and disordered solid solution as well the transition metal orderings within the ordered region of the phase diagram. We also provide a method to propagate the uncertainty at every level of the analysis to the final prediction of thermodynamically favorable compositional phases thus providing a quantitative measure of confidence for each prediction made. Due to the complexity of the three component system, as well as the intrinsic error of density functional theory, we argue that this propagation of uncertainty, particularly the uncertainty due to exchange-correlation functional choice is necessary to have reliable and interpretable results. We find that for the majority of transition metal compositions of the layered material, specifically medium to high-Ni content, prefer transition metal ordering and predict the collection of preferred compositions in the ordered region.

    更新日期:2019-12-11
  • Tribute to Michel Armand: from Rocking Chair - Li-ion to Solid-State Lithium Batteries
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2019-12-11
    Alain Mauger, Christian M. Julien, John B. Goodenough, Karim Zaghib

    Professor Michel Armand is one of the world's leading scientists in the R&D of modern energy storage systems. His scientific works have been devoted to the concepts and technologies of today's batteries, in particular, mastering research on electrodes and electrolytes. With respect to innovative discoveries, Michel had several scientific breakthroughs from the description of the solid-solution electrode and rocking-chair battery to the applications of novel materials utilized in all-solid-state batteries (SSBs); these refer to Li-ion, Na-ion, Li-S, and Li-air cells. At a young age, he formalized the concept of electrochemical intercalation and fabricated the first SSB with sodium-intercalated graphite as the electrode in 1972. Subsequently, he led the use of solid polymer electrolytes and developed lithium-metal-polymer batteries with vanadium oxide as the cathode in 1978. Michel successfully conducted research in new salts topics based on delocalized anions of the sulfonimide family in 1986; his research areas included 1) organic electrode materials, i.e., innovations in redox-active organics, which included poly quinones and aromatic dicarboxylates, and 2) carbon “nano painting” process that has made LiFePO4@C the safest cathode in 2002. Because Michel has co-authored over 500 publications and many patents, it is impractical to fully review his outstanding contributions in electrochemistry in this work. This work is limited to a few of his contributions pertaining to the evolution of electrochemical energy storage. We further discussed different routes envisioned for further progress in rechargeable batteries.

    更新日期:2019-12-11
  • An In Situ Polymerized Comb-Like PLA/PEG-based Solid Polymer Electrolyte for Lithium Metal Batteries
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2019-12-04
    Muhammad Zaheer, Hongli Xu, Bingbing Wang, Lianwei Li, Yonghong Deng

    High ionic conductivity is a prerequisite for the application of solid-state polymer electrolyte towards the safe and high energy density electrochemical devices. Here we report the preparation and properties of an in-situ polymerized comb-like copolymer-based SPE (PLA/PEG-SPE) with high ionic conductivity from methyl acrylate functionalized poly(D,L-Lactide) (PLAMA) and poly(ethylene glycol) methyl ether methacrylate (PEGMA). A remarkably high ionic conductivity value of 6.9 × 10−5 S cm−1 at ambient temperature and a maximum ionic conductivity of 4.3 × 10−4 S cm−1 at 60°C were detected, with an activation energy of 0.2 eV and a Li+ transference number (tLi+) of 0.36. The PLA/PEG-SPE exhibits a wide electrochemical stability window up to 4.6 vs. Li/Li+ and very good lithium metal electrode compatibility. Solid-state LiFePO4/SPE/Li cells with integrated cathode and lithium metal deliver superior cycling stability with high discharge capacities (149 mAh g−1 as the initial specific capacity) and high capacity retention (exceeded 82% of its initial specific capacity) at 0.2 C at 60°C. The solid-state cells are also capable of being cycled at room temperature at 0.2 C. This work highlights a facile, in-situ fabrication strategy involving a vinyl-functionalized PLA precursor that yields a high-performance ion-conducting membrane attractive for lithium metal battery applications.

    更新日期:2019-12-04
  • Ionic Liquid Electrolytes for Metal-Air Batteries: Interactions between O2, Zn2+ and H2O Impurities
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2019-12-04
    D. Alwast, J. Schnaidt, Z. Jusys, R. J. Behm

    Motivated by the potential of ionic liquids (ILs) to replace traditional aqueous electrolytes in Zn-air batteries, we investigated the effects arising from mutual interactions between O2 and Zn(TFSI)2 as well as the influence of H2O impurities in the oxygen reduction/oxygen evolution reaction (ORR/OER) and in Zn deposition/dissolution on a glassy carbon (GC) electrode in the ionic liquid N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)-imide (BMP-TFSI) by differential electrochemical mass spectrometry. This allowed us to determine the number of electrons transferred per reduced/evolved O2 molecule. In O2 saturated neat BMP-TFSI the ORR and OER were found to be reversible, in Zn2+ containing IL Zn deposition/stripping proceeds reversibly as well. Simultaneous addition of O2 and Zn2+ suppresses Zn metal deposition, instead ZnO2 is formed in the ORR, which is reversible only after excursions to very negative potentials (−1.4 V). The addition of water leads to an enhancement of all processes described above, which is at least partly explained by a higher mobility of O2 and Zn2+ in the water containing electrolytes. Consequences for the operation of Zn-air batteries in these electrolytes are discussed.

    更新日期:2019-12-04
  • On the Road to a Multi-Coaxial-Cable Battery: Development of a Novel 3D-Printed Composite Solid Electrolyte
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2019-12-03
    Heftsi Ragones, Adi Vinegrad, Gilat Ardel, Meital Goor, Yossi Kamir, Moty Marcos Dorfman, Alexander Gladkikh, Diana Golodnitsky

    The high areal-energy and power requirements of advanced microelectronic devices favor the choice of a lithium-ion system, since it provides the highest energy density of available battery technologies suitable for a variety of applications. Several attempts have been made to produce primary and secondary thin‐film batteries utilizing printing techniques. These technologies are still at an early stage, and most currently-printed batteries exploit printed electrodes sandwiching self‐standing commercial polymer membranes, produced by conventional extrusion or papermaking techniques, followed by soaking in non-aqueous liquid electrolytes. In this work, we suggest a novel flexible-battery design and report the initial results of development and characterization of novel 3D printed all-solid-state electrolytes prepared by fused-filament fabrication (FFF). The electrolytes are composed of LiTFSI, polyethylene oxide (PEO), which is a known lithium-ion conductor, and polylactic acid (PLA) for enhanced mechanical properties and high-temperature durability. The 3D printed electrolytes were characterized by means of ESEM imaging, mass spectroscopy, differential scanning calorimetry (DSC) and electrochemical impedance spectroscopy (EIS). TOFSIMS analysis reveals formation of lithium complexes with both polymers. The flexible all-solid LiTFSI-based electrolyte exhibited bulk ionic conductivity of 3 × 10−5 S/cm at 90°C and 156ohmxcm2 resistance of the solid electrolyte interphase (SEI). We believe that the coordination mechanism of the lithium cation by the oxygen of the PLA chain is similar to that of PEO and local relaxation motions of PLA chain segments could promote Li-ion hopping between oxygens of adjacent CH-O groups. What is meant by this is that PLA not only improves the mechanical properties of PEO, but also serves as a Li-ion-conducting medium. These results pave the way for a fully printed solid battery, which enables free-form-factor flexible geometries.

    更新日期:2019-12-04
  • WS2/Graphene Composite as Cathode for Rechargeable Aluminum-Dual Ion Battery
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2019-11-18
    M. Latha, J. Vatsala Rani

    Tungsten disulfide/graphene nano-sheets (WS2/G) composite is prepared by the ultra-sonication process and applied as a cathode for rechargeable Aluminum-dual ion battery (ADIBs). X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), Fourier transform-infra red spectroscopy (FT-IR) and Raman spectroscopy are used to examine the morphology and architecture of the composite. WS2/G composite displays good electrochemical performance with remarkable specific capacity (152 mA h/g) and good cyclic stability (150 cycles). The aluminum-dual ion intercalation mechanism in the composite is analyzed by XRD, Raman and XPS analysis. WS2/G composite exhibits better electrochemical results than neat WS2, owing to the synergistic effect between highly conductive graphene and WS2.

    更新日期:2019-11-18
  • Lithium Electrodeposition in Single Molten Salt with Constant Lithium-Ion Concentration at Any Time and Location
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2019-11-18
    Hikaru Sano, Keigo Kubota, Zyun Siroma, Susumu Kuwabata, Hajime Matsumoto

    Although the mechanism of lithium dendritic growth is still under discussion, several researchers have reported that insufficient mass transfer causes dendrite formation. Recently, the synthesis of a single lithium molten salt, lithium (fluorosulfonyl)(trifluoromethylsulfonyl)amide (Li[FTA], m.p. 100°C), was reported, which can be used with a lithium electrode (m.p. 180°C). In this study, we focused on lithium electrodeposition from Li[FTA], where the lithium-ion concentration is constant at any time and location, even during electrodeposition, such that the mass transfer is always sufficient. Consequently, the formation of needle-like dendrites was suppressed using this single lithium molten salt. Thus, results imply that using a molten salt, such as Li[FTA], is a potential solution for the dendrite problem.

    更新日期:2019-11-18
  • Electrochemical and Microstructural Investigations of PtFe Nanocompounds Synthesized by Atmospheric-Pressure Plasma Jet
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2019-10-15
    You-Yu Chen, Min-Hsin Yeh, Tsai-Fu Chung, Shao-Pu Tsai, Jer-Ren Yang, Cheng-Che Hsu, Kuo-Chuan Ho, I-Chun Cheng, Jian-Zhang Chen

    A nitrogen DC-pulse atmosphere pressure plasma jet (APPJ) is used to convert ferric nitrate (Fe(NO3)3) and chloroplatinic acid (H2PtCl6) mixed liquid precursor films into PtFe nanocompounds on a fluorine-doped tin oxide (FTO) substrate. Scanning transmission electron microscopy indicates nanoparticles distributed on a thin continuous layer on the FTO substrate. The APPJ-synthesized PtFe nanocompounds contain a mixture of crystalline and amorphous phases. X-ray photoelectron spectroscopy shows that most Pt is in the metallic phase and most Fe, in the oxidized phase. A dye-sensitized solar cell (DSSC) with only 5-s APPJ-processed PtFe counter electrode (CE) shows significantly improved efficiency. This suggests the rapid processing capability of the nitrogen DC-pulse APPJ. A PtFe prepared with higher H2PtCl6/Fe(NO3)3 volume ratio shows better catalytic performance, as confirmed by cyclic voltammetry, electrochemical impedance spectroscopy, and Tafel experiments. The DSSC with APPJ-processed PtFe CE shows comparable efficiency to that of 15-min furnace-calcined Pt CE, suggesting that the APPJ processed PtFe requires less Pt.

    更新日期:2019-11-17
  • High Performance Direct N2H4-H2O2 Fuel Cell Using Fiber-Shaped Co Decorated with Pt Crystallites as Anode Electrocatalysts
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2019-11-01
    A. Zabielaitė, A. Balčiūnaitė, D. Šimkūnaitė, S. Lichušina, I. Stalnionienė, B. Šimkūnaitė-Stanynienė, L. Naruškevičius, L. Tamašauskaitė-Tamašiūnaitė, E. Norkus, A. Selskis, V. Pakštas

    In this study, a fiber-shaped Co coating was electroplated on the Cu surface followed by the deposition of Pt crystallites using the galvanic displacement method. The electrochemical behavior of the prepared Cofiber and Pt nanoparticles decorated Cofiber catalysts were evaluated in order to provide insights into the electro-oxidation of N2H4 in an alkaline media was performed using cyclic voltammetry and chrono-techniques. The influence of Cofiber/Cu and PtCofiber/Cu as the anode electrocatalyst on the performance of direct N2H4-H2O2 fuel cell was investigated at different temperatures. The deposition of a small amount of Pt crystallites, in the range of 5 μgPt cm–2 to 29 μgPt cm–2, significantly improved the performance of the fiber-shaped Co catalyst for the electro-oxidation of N2H4 in an alkaline medium. The measured N2H4 oxidation current densities at −0.2 V are approximately 5–6 times larger for different PtCofiber/Cu catalysts, compared with that of a pure Cofiber/Cu. The single N2H4-H2O2 fuel cell results showed that the highest peak power density of 219.8 mW cm–2 for the N2H4-H2O2 fuel cell was obtained with the PtCofiber/Cu catalyst that has the Pt loading of 28.7 μgPt cm–2.

    更新日期:2019-11-01
  • Solid-State NMR Studies of Chemically Lithiated CF.
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2010-08-03
    N D Leifer,V S Johnson,R Ben-Ari,H Gan,J M Lehnes,R Guo,W Lu,B C Muffoletto,T Reddy,P E Stallworth,S G Greenbaum

    Three types of fluorinated carbon, all in their original form and upon sequential chemical lithiations via n-butyllithium, were investigated by (13)C and (19)F solid-state NMR methods. The three starting CF(x) materials [where x = 1 (nominally)] were fiber based, graphite based, and petroleum coke based. The aim of the current study was to identify, at the atomic/molecular structural level, factors that might account for differences in electrochemical performance among the different kinds of CF(x). Differences were noted in the covalent F character among the starting compounds and in the details of LiF production among the lithiated samples.

    更新日期:2019-11-01
  • Li Ion Conducting Polymer Gel Electrolytes Based on Ionic Liquid/PVDF-HFP Blends.
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2007-09-21
    Hui Ye,Jian Huang,Jun John Xu,Amish Khalfan,Steve G Greenbaum

    Ionic liquids thermodynamically compatible with Li metal are very promising for applications to rechargeable lithium batteries. 1-methyl-3-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide (P(13)TFSI) is screened out as a particularly promising ionic liquid in this study. Dimensionally stable, elastic, flexible, nonvolatile polymer gel electrolytes (PGEs) with high electrochemical stabilities, high ionic conductivities and other desirable properties have been synthesized by dissolving Li imide salt (LiTFSI) in P(13)TFSI ionic liquid and then mixing the electrolyte solution with poly(vinylidene-co-hexafluoropropylene) (PVDF-HFP) copolymer. Adding small amounts of ethylene carbonate to the polymer gel electrolytes dramatically improves the ionic conductivity, net Li ion transport concentration, and Li ion transport kinetics of these electrolytes. They are thus favorable and offer good prospects in the application to rechargeable Li batteries including open systems like Li/air batteries, as well as more "conventional" rechargeable lithium and lithium ion batteries.

    更新日期:2019-11-01
  • Lithium-Ion-Conducting Electrolytes: From an Ionic Liquid to the Polymer Membrane.
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2010-04-01
    A Fernicola,F C Weise,S G Greenbaum,J Kagimoto,B Scrosati,A Soleto

    This work concerns the design, the synthesis, and the characterization of the N-butyl-N-ethylpiperidinium N,N-bis(trifluoromethane)sulfonimide (PP(24)TFSI) ionic liquid (IL). To impart Li-ion transport, a suitable amount of lithium N,N-bis-(trifluoromethane)sulfonimide (LiTFSI) is added to the IL. The Li-IL mixture displays ionic conductivity values on the order of 10(-4) S cm(-1) and an electrochemical stability window in the range of 1.8-4.5 V vs Li(+)/Li. The voltammetric analysis demonstrates that the cathodic decomposition gives rise to a passivating layer on the surface of the working electrode, which kinetically extends the stability of the Li/IL interface as confirmed by electrochemical impedance spectroscopy measurements. The LiTFSI-PP(24)TFSI mixture is incorporated in a poly(vinylidene fluoride-co-hexafluoropropylene) matrix to form various electrolyte membranes with different LiTFSI-PP(24)TFSI contents. The ionic conductivity of all the membranes resembles that of the LiTFSI-IL mixture, suggesting an ionic transport mechanism similar to that of the liquid component. NMR measurements demonstrate a reduction in the mobility of all ions following the addition of LiTFSI to the PP(24)TFSI IL and when incorporating the mixture into the membrane. Finally, an unexpected but potentially significant enhancement in Li transference number is observed in passing from the liquid to the membrane electrolyte system.

    更新日期:2019-11-01
  • Design and Finite Element Model of a Microfluidic Platform with Removable Electrodes for Electrochemical Analysis.
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2019-07-26
    Daniel E Molina,Adan Schafer Medina,Haluk Beyenal,Cornelius F Ivory

    A microfluidic platform for hydrodynamic electrochemical analysis was developed, consisting of a poly(methyl methacrylate) chip and three removable electrodes, each housed in 1/16" OD polyether ether ketone tube which can be removed independently for polishing or replacement. The working electrode was a 100-μm diameter Pt microdisk, located flush with the upper face of a 150 μm × 20 μm × 3 cm microchannel, smaller than previously reported for these types of removable electrodes. A commercial leak-less reference electrode was utilized, and a coiled platinum wire was the counter electrode. The platform was evaluated electrochemically by oxidizing a potassium ferrocyanide solution at the working electrode, and a typical limiting current behavior was observed after running linear sweep voltammetry and chronoamperometry, with flow rates 1-6 μL/min. While microdisk channel electrodes have been simulated before using a finite difference method in an ideal 3D geometry, here we predict the limiting current using finite elements in COMSOL Multiphysics 5.3a, which allowed us to easily explore variations in the microchannel geometry that have not previously been considered in the literature. Experimental and simulated currents showed the same trend but differed by 41% in simulations of the ideal geometry, which improved when channel and electrode imperfections were included.

    更新日期:2019-11-01
  • Communication-Carbon Nanotube Fiber Microelectrodes for High Temporal Measurements of Dopamine.
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2018-09-11
    Alexander G Zestos,B Jill Venton

    Carbon nanotube (CNT) yarn and fiber-microelectrodes were developed for neurotransmitter detection using fast scan cyclic voltammetry (FSCV). Fibers were made by suspending CNTs in acid/surfactant and extruding into acetone/polyethyleneimine (PEI) and compared to a CNT yarn. They were FSCV frequency independent for dopamine up to 100 Hz. With faster frequencies, up to 500 Hz, high currents are maintained, which allows a 2 ms sampling rate for FSCV, compared to 100 ms. CNT fibers have rough surfaces which trap dopamine and dopamine-o-quinone (DOQ), creating more reversible CVs. CNT yarns and fibers are beneficial for high sensitivity, rapid measurements of neurotransmitters.

    更新日期:2019-11-01
  • Superconformal Bottom-Up Gold Deposition in High Aspect Ratio Through Silicon Vias.
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2017-07-22
    D Josell,T P Moffat

    This work presents superconformal, bottom-up Au filling of high aspect ratio through silicon vias (TSVs) along with a predictive framework based on the coupling of suppression breakdown and surface topography. The work extends a previous study of superconformal Au deposition in lower aspect ratio TSVs. Deposition was performed in a Na3AuSO3 electrolyte containing a branched polyethyleneimine (PEI) deposition-rate suppressing additive. Voltammetric measurements using a rotating disk electrode (RDE) were used to assess the impact of the PEI suppressor concentration and transport on the rate of metal deposition, enabling the interplay between metal deposition and suppressor adsorption to be quantified. The positive feedback associated with suppression breakdown gives rise to an S-shaped negative differential resistance (S-NDR). The derived kinetics for suppressor adsorption and consumption were used in a mass conservation model to account for bottom-up filling of patterned features. Predictions, including the impact of deposition potential and additive concentration on feature filling, are shown to match experimental results for filling of TSVs. This further generalizes the utility of the additive derived S-NDR model as a predictive formalism for identifying additives capable of generating localized, void-free filling of TSVs by electrodeposition.

    更新日期:2019-11-01
  • Review-Mathematical Formulations of Electrochemically Gas-Evolving Systems.
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2018-12-14
    Amir Taqieddin,Michael R Allshouse,Akram N Alshawabkeh

    Electrochemically gas-evolving systems are utilized in alkaline water electrolysis, hydrogen production, and many other applications. To design and optimize these systems, high-fidelity models must account for electron-transfer, chemical reactions, thermodynamics, electrode porosity, and hydrodynamics as well as the interconnectedness of these phenomena. Further complicating these models is the production and presence of bubbles. Bubble nucleation naturally occurs due to the chemical reactions and impacts the reaction rate. Modeling bubble growth requires an accurate accounting of interfacial mass transfer. When the bubble becomes large, detachment occurs and the system is modeled as a two-phase flow where the bubbles can then impact material transport in the bulk. In this paper, we review the governing mathematical models of the physicochemical life cycle of a bubble in an electrolytic medium from a multiscale, multiphysics viewpoint. For each phase of the bubble life cycle, the prevailing mathematical formulations are reviewed and compared with particular attention paid to physicochemical processes and the impact the bubble. Through the review of a broad range of models, we provide a compilation of the current state of bubble modeling in electrochemically gas-evolving systems.

    更新日期:2019-11-01
  • Kinetics and Thermodynamics of Hydrogen Oxidation and Oxygen Reduction in Hydrophobic Room-Temperature Ionic Liquids.
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2009-01-01
    Julie B Rollins,John C Conboy

    In this study 1-dodecyl-3-methylimidazolium (C(12)mim) bis(pentafluoroethylsulfonyl)imide (BETI) and 1-dodecylimidazolium (C(12)im) BETI hydrophobic room-temperature ionic liquids (RTILs) were synthesized and used as proton-conducting electrolytes in a nonhumidified feed gas electrochemical cell. The ionic conductivities of C(12)mimBETI and C(12)imBETI were similar and increased linearly with an increase in temperature from 20 to 130°C. However, when used in the electrochemical system the protic water-equilibrated C(12)imBETI had a larger maximum current and power density compared to the aprotic water-equilibrated C(12)mimBETI. The effect of water content on the reaction rates and thermodynamics of these hydrophobic RTILs was also examined. The efficiency of the C(12)mimBETI increased upon removal of water while that of the C(12)imBETI decreased in efficiency when water was removed. The water structure in these RTILs was examined using attenuated total internal reflection Fourier transform IR spectroscopy and depended on the chemical structure of the cation. These studies give further insight into the possible mechanism of proton transport in these RTIL systems.

    更新日期:2019-11-01
  • Electrochemical Properties of Carbon Nanoparticles Entrapped in Silica Matrix.
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2008-10-28
    Sangho Bok,Arnold A Lubguban,Yuanfang Gao,Shantanu Bhattacharya,Venu Korampally,Maruf Hossain,Kevin D Gillis,Shubhra Gangopadhyay

    Carbon-based electrode materials have been widely used for many years for electrochemical charge storage, energy generation, and catalysis. We have developed an electrode material with high specific capacitance by entrapping graphite nanoparticles into a sol-gel network. Films from the resulting colloidal suspensions were highly porous due to the removal of the entrapped organic solvents from sol-gel matrix giving rise to high Brunauer-Emmett-Teller (BET) specific surface areas (654 m(2)/g) and a high capacitance density ( approximately 37 F/g). An exponential increase of capacitance was observed with decreasing scan rates in cyclic voltammetry studies on these films suggesting the presence of pores ranging from micro (< 2 nm) to mesopores. BET surface analysis and scanning electron microscope images of these films also confirmed the presence of the micropores as well as mesopores. A steep drop in the double layer capacitance with polar electrolytes was observed when the films were rendered hydrophilic upon exposure to a mild oxygen plasma. We propose a model whereby the microporous hydrophobic sol-gel matrix perturbs the hydration of ions which moves ions closer to the graphite nanoparticles and consequently increase the capacitance of the film.

    更新日期:2019-11-01
  • Platinum Electrodeposition on Unsupported Single Wall Carbon Nanotubes and Its Application as Methane Sensing Material.
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2012-01-01
    Enid Contes-de Jesus,Diana Santiago,Gilberto Casillas,Alvaro Mayoral,Cesar Magen,Miguel José-Yacaman,Jing Li,Carlos R Cabrera

    This paper reports the decoration of single wall carbon nanotubes (SWCNTs) with platinum (Pt) nanoparticles using an electrochemical technique, rotating disk slurry electrode (RoDSE). Pt/SWCNTs were electrochemically characterized by cyclic voltammetry technique (CV) and physically characterized through the use of transmission electron microscopy (TEM), energy dispersive spectroscopy - X-ray florescence (EDS-XRF) and X-ray diffraction (XRD). After characterization it was found that electrodeposited nanoparticles had an average particle size of 4.1 ± 0.8 nm. Pt/SWCNTs were used as sensing material for methane (CH4) detection and showed improved sensing properties in a range of concentration from 50 ppm to 200 ppm parts per million (ppm) at room temperature, when compared to other Pt/CNTs-based sensors. The use of this technique for the preparation of Pt/SWCNTs opens a new possibility in the bulk preparation of samples using an electrochemical method and thus their potential use in a wide variety of applications in chemical sensing, fuel cell and others.

    更新日期:2019-11-01
  • Improving Reproducibility of Lab-on-a-Chip Sensor with Bismuth Working Electrode for Determining Zn in Serum by Anodic Stripping Voltammetry.
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2014-04-15
    Xing Pei,Wenjing Kang,Wei Yue,Adam Bange,William R Heineman,Ian Papautsky

    This work reports on the continuing development of a lab-on-a-chip electrochemical sensor for determination of zinc in blood serum using square wave anodic stripping voltammetry. The microscale sensor consists of a three electrode system, including an environmentally friendly bismuth working electrode, an integrated silver/silver chloride reference electrode, and a gold auxiliary electrode. The sensor demonstrates a linear response in 0.1 M acetate buffer at pH 6 for zinc concentrations in the 1-30 μM range. By optimizing bismuth film deposition and better control of the fabrication process, repeatability of the sensor was improved, reducing variability from 42% to <2%. Through optimization of electrolyte and stripping voltammetry parameters, limit of detection was greatly improved to 60 nM. The optimized sensor was also able to measure zinc in the extracted blood serum. Ultimately, with integrated sample preparation, the sensor will permit rapid (min) measurements of zinc from a sub-mL sample (a few drops of blood) for clinical applications.

    更新日期:2019-11-01
  • Investigation of dynamics in BMIM TFSA ionic liquid through variable temperature and pressure NMR relaxometry and diffusometry.
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2017-01-01
    Kartik Pilar,Armando Rua,Sophia N Suarez,Christopher Mallia,Shen Lai,J R P Jayakody,Jasmine L Hatcher,James F Wishart,Steve Greenbaum

    A comprehensive variable temperature, pressure and frequency multinuclear (1H, 2H, and 19F) magnetic resonance study was undertaken on selectively deuterated 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide (BMIM TFSA) ionic liquid isotopologues. This study builds on our earlier investigation of the effects of increasing alkyl chain length on diffusion and dynamics in imidazolium-based TFSA ionic liquids. Fast field cycling 1H T1 data revealed multiple modes of motion. Through calculation of diffusion coefficient (D) values and activation energies, the low- and high-field regimes were assigned to the translational and reorientation dynamics respectively. Variable-pressure 2H T1 measurements reveal site-dependent interactions in the cation with strengths in the order MD3 > CD3 > CD2, indicating dissimilarities in the electric field gradients along the alkyl chain, with the CD2 sites having the largest gradient. Additionally, the α saturation effect in T1 vs. P was observed for all three sites, suggesting significant reduction of the short-range rapid reorientational dynamics. This reduction was also deduced from the variable pressure 1H T1 data, which showed an approach to saturation for both the methyl and butyl group terminal methyl sites. Pressure-dependent D measurements show independent motions for both cations and anions, with the cations having greater D values over the entire pressure range.

    更新日期:2019-11-01
  • Review-Physicochemical hydrodynamics of gas bubbles in two phase electrochemical systems.
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2017-01-01
    Amir Taqieddin,Roya Nazari,Ljiljana Rajic,Akram Alshawabkeh

    Electrochemical systems suffer from poor management of evolving gas bubbles. Improved understanding of bubbles behavior helps to reduce overpotential, save energy and enhance the mass transfer during chemical reactions. This work investigates and reviews the gas bubbles hydrodynamics, behavior, and management in electrochemical cells. Although the rate of bubble growth over the electrode surface is well understood, there is no reliable prediction of bubbles break-off diameter from the electrode surface because of the complexity of bubbles motion near the electrode surface. Particle Image Velocimetry (PIV) and Laser Doppler Anemometry (LDA) are the most common experimental techniques to measure bubble dynamics. Although the PIV is faster than LDA, both techniques are considered expensive and time-consuming. This encourages adapting Computational Fluid Dynamics (CFD) methods as an alternative to study bubbles behavior. However, further development of CFD methods is required to include coalescence and break-up of bubbles for better understanding and accuracy. The disadvantages of CFD methods can be overcome by using hybrid methods. The behavior of bubbles in electrochemical systems is still a complex challenging topic which requires a better understanding of the gas bubbles hydrodynamics and their interactions with the electrode surface and bulk liquid, as well as between the bubbles itself.

    更新日期:2019-11-01
  • Electrochemical Detection of Dopamine via Assisted Ion Transfer at Nanopipet Electrode Using Cyclic Voltammetry.
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2016-01-01
    Michelle L Colombo,Swami McNeil,Nicholas Iwai,Albert Chang,Mei Shen

    We present here the detection of dopamine (DA) at nanopipet electrodes with radii of hundreds of nanometers ranging from 160 nm to 480 nm. Dibenzo-18-crown-6 (DB18C6) was employed as an ionophore to facilitate DA transfer, resulting in a half-wave transfer potential, E1/2, DA, of -0.322 (±0.020) V vs. E1/2, TBA. Well-defined steady-state sigmoidal cyclic voltammograms were observed for the transfer of DA. High resolution scanning electron microscopy was used to measure the size and taper angle of the nanopipet electrodes. The detection is linear with concentration of DA ranging from 0.25 mM to 2 mM; calculated diffusion coefficient at nanopipet electrodes with above mentioned sizes is 4.87 (±0.28) × 10-10 m2/s. The effect of the common interferent ascorbic acid on DA detection with nanopipet electrodes was evaluated, where DA detection still shows linear behavior with well-defined sigmoidal CVs with E1/2, DA being -0.328 (±0.029) V vs. E1/2, TBA. The diffusion coefficient for DA transfer in MgCl2 with the presence of 2 mM AA was measured to be 1.93 (±0.59) × 10-10 m2/s on nanoelectrodes with radii from 161 nm to 263 nm, but the physiological concentration of 0.1 mM AA had no effect on DA's diffusion coefficient.

    更新日期:2019-11-01
  • The Impact of Organic Additives on Copper Trench Microstructure.
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2017-12-12
    James B Marro,Chukwudi A Okoro,Yaw S Obeng,Kathleen C Richardson

    Organic additives are typically used in the pulse electrodeposition of copper (Cu) to prevent void formation during the filling of high aspect ratio features. In this work, the role of bath chemistry as modified by organic additives was investigated for its effects on Cu trench microstructure. Polyethylene glycol (PEG), bis(3-sulfopropyl) disulfide (SPS), and Janus green b (JGB) concentrations were varied in the Cu electrodeposition bath. Results indicated a correlation between the JGB/SPS ratio and the surface roughness and residual stresses in the Cu. Electron backscattering diffraction (EBSD) and transmission Kikuchi diffraction (TKD) were used to study the cross-sectional microstructure in the trenches. Finer grain morphologies appeared in trenches filled with organic additives as compared to additive-free structures. Cu trench (111) texture also decreased with increasing organic additive concentrations due to more pronounced influence of sidewall seed layers on trench features. Twin density in the microstructure closely tracked calculated stresses in the Cu trenches. A comprehensive microstructural analysis was conducted in this study, on an area of focus that has garnered little attention from the literature, yet can have a major impact on microelectronic reliability.

    更新日期:2019-11-01
  • INTEGRATED MICROFLUIDIC SELEX USING FREE SOLUTION ELECTROKINETICS.
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2017-11-25
    Timothy R Olsen,Claudia Tapia-Alveal,Kyung-Ae Yang,Xin Zhang,Leonardo Joe Pereira,Nickolaos Farmakidis,Renjun Pei,Milan N Stojanovic,Qiao Lin

    Systematic evolution of ligands by exponential enrichment (SELEX) offers a powerful method to isolate affinity oligonucleotides known as aptamers, which can then be used in a wide range of applications from drug delivery to biosensing. However, conventional SELEX methods rely on labor intensive and time consuming benchtop operations. A simplified microfluidic approach is presented which allows integration of the affinity selection and amplification stages of SELEX for the isolation of target-binding oligonucleotides by combining bead-based biochemical reactions with free solution electrokinetic oligonucleotide transfer. Free solution electrokinetics allows coupling of affinity selection and amplification for closed loop oligonucleotide enrichment without the need for offline processes, flow handling components or gel components, while bead based selection and amplification allow efficient manipulation of reagents and reaction products thereby realizing on-chip loop closure and integration of the entire SELEX process. Thus the approach is capable of multi-round enrichment of oligonucleotides using simple transfer processes while maintaining a high level of device integration, as demonstrated by the isolation of an aptamer pool against a protein target (IgA) with significantly higher binding affinity than the starting library in approximately 4 hours of processing time.

    更新日期:2019-11-01
  • Electrochemical Fluorination and Radiofluorination of Methyl(phenylthio)acetate Using Tetrabutylammonium Fluoride (TBAF).
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2017-09-12
    Mehrdad Balandeh,Christopher Waldmann,Daniela Shirazi,Adrian Gomez,Alejandra Rios,Nathanael Allison,Asad Khan,Saman Sadeghi

    Electrochemical fluorination of methyl(phenylthio)acetate was achieved using tetrabutylammonium fluoride (TBAF). Electrochemical fluorination was performed under potentiostatic anodic oxidation using an undivided cell in acetonitrile containing TBAF and triflic acid. The influence of several parameters including: oxidation potential, time, temperature, sonication, TBAF concentration and triflic acid concentration on fluorination efficiency were studied. It was found that the triflic acid to TBAF concentration ratio plays a key role in the fluorination efficiency. Electrochemical fluorination resulted in formation of mono-fluorinated methyl 2-fluoro-2-(phenylthio)acetate verified by gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance (NMR) Spectroscopy. Under optimum conditions 44 ± 3% mono fluorination yield was obtained after a 30 min electrolysis. Electrochemical radiofluorination for the synthesis of methyl 2-[18F]fluoro-2-(phenothio) acetate was also achieved with the same optimized electrochemical cell parameters where TBAF was first passed through an anion exchange resin containing fluorine-18. A radiochemical fluorination efficiency of 7 ± 1% was achieved after 30 min of electrolysis.

    更新日期:2019-11-01
  • Comparison of Nanoscale Focused Ion Beam and Electrochemical Lithiation in β-Sn Microspheres.
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2016-01-01
    Saya Takeuchi,William R McGehee,Jennifer L Schaefer,Truman M Wilson,Kevin A Twedt,Eddie H Chang,Christopher L Soles,Vladimir P Oleshko,Jabez J McClelland

    The development of Li focused ion beams (Li-FIB) enables controlled Li ion insertion into materials with nanoscale resolution. We take the first step toward establishing the relevance of the Li-FIB for studies of ion dynamics in electrochemically active materials by comparing FIB lithiation with conventional electrochemical lithiation of isolated β-Sn microspheres. Samples are characterized by cross-sectioning with Ga FIB and imaging via electron microscopy. The Li-FIB and electrochemical lithiated Sn exhibit similarities that suggest that the Li-FIB can be a powerful tool for exploring dynamical Li ion-material interactions at the nanoscale in a range of battery materials.

    更新日期:2019-11-01
  • Focused-Ion-Beam-Milled Carbon Nanoelectrodes for Scanning Electrochemical Microscopy.
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2016-09-20
    Ran Chen,Keke Hu,Yun Yu,Michael V Mirkin,Shigeru Amemiya

    Nanoscale scanning electrochemical microscopy (SECM) has emerged as a powerful electrochemical method that enables the study of interfacial reactions with unprecedentedly high spatial and kinetic resolution. In this work, we develop carbon nanoprobes with high electrochemical reactivity and well-controlled size and geometry based on chemical vapor deposition of carbon in quartz nanopipets. Carbon-filled nanopipets are milled by focused ion beam (FIB) technology to yield a flat disk tip with a thin quartz sheath as confirmed by transmission electron microscopy. The extremely high electroactivity of FIB-milled carbon nanotips is quantified by enormously high standard electron-transfer rate constants of ≥10 cm/s for Ru(NH3)63+. The tip size and geometry are characterized in electrolyte solutions by SECM approach curve measurements not only to determine inner and outer tip radii of down to ~27 and ~38 nm, respectively, but also to ensure the absence of a conductive carbon layer on the outer wall. In addition, FIB-milled carbon nanotips reveal the limited conductivity of ~100 nm-thick gold films under nanoscale mass-transport conditions. Importantly, carbon nanotips must be protected from electrostatic damage to enable reliable and quantitative nanoelectrochemical measurements.

    更新日期:2019-11-01
  • Communication-Microelectrode Detection of Cholesterol Efflux from the Human Buccel Mucosa.
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2016-08-23
    Xiaochun Yu,Thomas J Kelley,Hillel J Chiel,James D Burgess

    It has previously demonstrated that cholesterol efflux from the cell plasma membrane is increased in a mouse model of cystic fibrosis (CF) compared to a wild-type control. A noninvasive means of characterizing plasma membrane cholesterol efflux at the surface of airway tissue of CF patients is needed to extend the trends found in animal models of CF to the human disease state. Microelectrode-induced cholesterol efflux from the plasma membrane of cells at the surface of tissue is proposed as a strategy to demonstrate increased cholesterol efflux for CF in human subjects. Data demonstrating detection of cholesterol efflux from the human buccal mucosa is reported as proof-of-concept for an in vivo diagnostic assay.

    更新日期:2019-11-01
  • Double Potential Pulse Chronocoulometry for Detection of Plasma Membrane Cholesterol Efflux at Disk Platinum Microelectrodes.
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2014-01-01
    Richard H West,Hui Lu,Kendrick Shaw,Hillel J Chiel,Thomas J Kelley,James D Burgess

    A double potential pulse scheme is reported for observation of cholesterol efflux from the plasma membrane of a single neuron cell. Capillary Pt disk microelectrodes having a thin glass insulator allow the 10 μm diameter electrode and cell to be viewed under optical magnification. The electrode, covalently functionalized with cholesterol oxidase, is positioned in contact with the cell surface resulting in enzyme catalyzed cholesterol oxidation and efflux of cholesterol from the plasma membrane at the electrode contact site. Enzymatically generated hydrogen peroxide accumulates at the electrode/cell interface during a 5 s hold-time and is oxidized during application of a potential pulse. A second, replicate potential pulse is applied 0.5 s after the first potential pulse to gauge background charge prior to significant accumulation of hydrogen peroxide. The difference in charge passed between the first and second potential pulse provides a measure of hydrogen peroxide generated by the enzyme and is an indication of the cholesterol efflux. Control experiments for bare Pt microelectrodes in contact with the cell plasma membrane show difference charge signals in the range of about 7-10 pC. Enzyme-modified electrodes in contact with the plasma membrane show signals in the range of 16-26 pC.

    更新日期:2019-11-01
  • A Search for the Optimum Lithium Rich Layered Metal Oxide Cathode Material for Li-Ion Batteries.
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2015-10-20
    Mehmet Nurullah Ates,Sanjeev Mukerjee,K M Abraham

    We report the results of a comprehensive study of the relationship between electrochemical performance in Li cells and chemical composition of a series of Li rich layered metal oxides of the general formula xLi2MnO3 · (1-x)LiMn0.33Ni0.33Co0.33O2 in which x = 0,1, 0.2, 0,3, 0.5 or 0.7, synthesized using the same method. In order to identify the cathode material having the optimum Li cell performance we first varied the ratio between Li2MnO3 and LiMO2 segments of the composite oxides while maintaining the same metal ratio residing within their LiMO2 portions. The materials with the overall composition 0.5Li2MnO3 · 0.5LiMO2 containing 0.5 mole of Li2MnO3 per mole of the composite metal oxide were found to be the optimum in terms of electrochemical performance. The electrochemical properties of these materials were further tuned by changing the relative amounts of Mn, Ni and Co in the LiMO2 segment to produce xLi2MnO3 · (1-x)LiMn0.50Ni0.35Co0.15O2 with enhanced capacities and rate capabilities. The rate capability of the lithium rich compound in which x = 0.3 was further increased by preparing electrodes with about 2 weight-percent multiwall carbon nanotube in the electrode. Lithium cells prepared with such electrodes were cycled at the 4C rate with little fade in capacity for over one hundred cycles.

    更新日期:2019-11-01
  • The Role of OOH Binding Site and Pt Surface Structure on ORR Activities.
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2014-01-01
    Qingying Jia,Keegan Caldwell,Joseph M Ziegelbauer,Anusorn Kongkanand,Frederick T Wagner,Sanjeev Mukerjee,David E Ramaker

    We present experimentally observed molecular adsorbate coverages (e.g., O(H), OOH and HOOH) on real operating dealloyed bimetallic PtMx (M = Ni or Co) catalysts under oxygen reduction reaction (ORR) conditions obtained using X-ray absorption near edge spectroscopy (XANES). The results reveal a complex Sabatier catalysis behavior and indicate the active ORR mechanism changes with Pt-O bond weakening from the O2 dissociative mechanism, to the peroxyl mechanism, and finally to the hydrogen peroxide mechanism. An important rearrangement of the OOH binding site, an intermediate in the ORR, enables facile H addition to OOH and faster O-O bond breaking on 111 faces at optimal Pt-O bonding strength, such as that occurring in dealloyed PtM core-shell nanoparticles. This rearrangement is identified by previous DFT calculations and confirmed from in situ measured OOH adsorption coverages during the ORR. The importance of surface structural effects and 111 ordered faces is confirmed by the higher specific ORR rates on solid core vs porous multi-core nanoparticles.

    更新日期:2019-11-01
  • How Metallic Protection Layers Extend the Lifetime of NASICON-Based Solid-State Lithium Batteries
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2019-10-11
    Francisco Javier Quintero Cortes, John A. Lewis, Jared Tippens, Thomas S. Marchese, Matthew T. McDowell

    The use of solid-state electrolytes (SSEs) within batteries is a promising strategy to safely access the high capacity of lithium metal anodes. However, most SSEs with practical ionic conductivity are chemically unstable in contact with lithium metal, which is detrimental to battery performance. Lithium aluminum germanium phosphate (LAGP) is an SSE with high ionic conductivity (10−4-10−3 S cm−1) and good environmental stability, but it forms an amorphous interphase region that continuously grows in contact with Li, leading to chemo-mechanical failure within solid-state batteries. Here, we find that thin (∼30 nm) chromium interlayers deposited between the lithium electrode and LAGP extend cycle life to over 1000 h at moderate current densities (0.1–0.2 mA cm−2), compared to ∼30 h without protection. This significantly improved stability occurs because the metallic interlayer alters the trajectory of interphase formation and the nature of the electrochemical reaction at the interface. This work shows the promise of interface engineering for a variety of SSE materials within solid-state batteries, while emphasizing the necessity of understanding how protection layers affect dynamic evolution of interfaces.

    更新日期:2019-10-12
  • The Importance of Water Transport in High Conductivity and High-Power Alkaline Fuel Cells
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2019-10-09
    Mrinmay Mandal, Garrett Huang, Noor Ul Hassan, Xiong Peng, Taoli Gu, Ahmon H. Brooks-Starks, Bamdad Bahar, William E. Mustain, Paul A. Kohl

    High ionic conductivity membranes can be used to minimize ohmic losses in electrochemical devices such as fuel cells, flow batteries, and electrolyzers. Very high hydroxide conductivity was achieved through the synthesis of a norbornene-based tetrablock copolymer with an ion-exchange capacity of 3.88 meq/g. The membranes were cast with a thin polymer reinforcement layer and lightly cross-linked with N,N,N′,N′-tetramethyl-1,6-hexanediamine. The norbornene polymer had a hydroxide conductivity of 212 mS/cm at 80°C. Light cross-linking helped to control the water uptake and provide mechanical stability while balancing the bound (i.e. waters of hydration) vs. free water in the films. The films showed excellent chemical stability with <1.5% conductivity loss after soaking in 1 M NaOH for 1000 h at 80°C. The aged films were analyzed by FT-IR before and after aging to confirm their chemical stability. A H2/O2 alkaline polymer electrolyte fuel cell was fabricated and was able to achieve a peak power density of 3.5 W/cm2 with a maximum current density of 9.7 A/cm2 at 0.15 V at 80°C. The exceptionally high current and power densities were achieved by balancing and optimizing water removal and transport from the hydrogen negative electrode to the oxygen positive electrode. High water transport and thinness are critical aspects of the membrane in extending the power and current density of the cells to new record values.

    更新日期:2019-10-10
  • Synthesis and Characterization of Core-Shell Nanocrystals of Co-Rich Cathodes
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2019-10-01
    Bob Jin Kwon, Fulya Dogan, Jacob R. Jokisaari, Baris Key, Igor L. Bolotin, Tadas Paulauskas, Chunjoong Kim, Robert F. Klie, Jordi Cabana

    Interfacial stability between the cathode and the electrolyte in Li-ion batteries directly determines durability upon cycling. Core-shell nanoscale heterostructures offer high precision when replacing redox-active ions on the surface with inactive species such as Al ions to suppress these deleterious reactions. However, the level of compositional complexity of leading cathodes for high-energy devices, while showing increased stability, remains to be demonstrated for these heterostructures. A combination of colloidal synthesis and subsequent post-annealing process was used to produce cores of LiCo0.5Ni0.25Mn0.25O2, a layered oxide with a high theoretical capacity, with epitaxial and conformal shells with increasing concentration of Al from the interior to surface. Thorough insight at high chemical and spatial resolution was obtained by a combination of characterization techniques. The gradient of Al was controlled by the initial content and the temperature of synthesis. The passivation layers play a critical role in notably increasing the retention of capacity, which was particularly considerable under harsh conditions such as wide potential window and, especially, elevated temperature, which accelerate side reactions. Spectroscopic analysis revealed that the tailored surface layers mainly stabilized the electronic environment at the surface, suggesting a possible explanation to the improved battery performance.

    更新日期:2019-10-01
  • Review--Recent Advances in Block-Copolymer Nanostructured Subwavelength Antireflective Surfaces
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2019-09-20
    Sajjad Husain Mir, Gaulthier Rydzek, Larry Akio Nagahara, Ajit Khosla, Parvaneh Mokarian-Tabari

    Nanostructured Anti-Reflective (AR) surfaces have attracted a focused attention during the last few years and offer an alternative to AR coatings. Recent nanopatterning approaches have allowed fabrication of bioinspired nanostructured surfaces with unprecedented broadband and omnidirectional AR properties. However, nanofabrication methods face major challenges for reaching industrial maturity including high capital expenditure cost, scalability, reliability and adaptability of the technologies. Block copolymer (BCP) films provide one way to overcome some of these limitations by offering scalable and versatile masks to fabricate well-defined, uniform and tunable nanostructures on a variety of substrates at a modest price. This article aims at highlighting recent efforts for assembling such AR nanostructured surfaces with BCP films and the challenges yet to tackle prior to commercialization of the technology.

    更新日期:2019-09-21
  • Review--Conducting Polymers as Chemiresistive Gas Sensing Materials: A Review
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2019-09-20
    Yung Cheng Wong, Bee Chin Ang, A. S. M. A. Haseeb, Aainaa Aqilah Baharuddin, Yew Hoong Wong

    Detection of harmful gases is important to ensure human and environmental health. Industrial waste gases such as CO, NO2, H2S, and NH3 are of typical focus among researchers over the years. Chemiresistive sensors are suitable for detecting these harmful gases. One suitable candidate material for this sensor is the conducting polymer, which offers the advantage of room-temperature operation. This review focuses on the overall development of conducting polymer as chemiresistive sensing materials. Effects of different parameters influencing sensor performance such as response, gas concentration, response time, and recovery time of conducting polymers are explored. Different conducting polymers are compared and their affinities to specific gases are determined. An understanding of pure conducting polymers assists further exploration of these polymers in composite form. A comprehensive understanding based on an overview of literature will facilitate researchers in selecting appropriate conducting polymers for different gas sensing applications and is expected to encourage further progress in this area.

    更新日期:2019-09-21
  • Review--Pencil Graphite Electrode: An Emerging Sensing Material
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2019-09-17
    Annu, Swati Sharma, Rajeev Jain, Antony Nitin Raja

    Pencil is one of the most widely used electrode material in electrochemical sensing of various organic and inorganic species with significant lower detection limit. Due to their lower background currents, superior sensitivity, reproducibility, amendable electroactive surface area, cost effective and ease of disposability, pencil graphite electrode has gain considerable attention in recent years. It signifies a viable substitute to other expensive traditional electrodes such as Glassy carbon, Gold, Boron-doped-diamond, platinum etc. This review addresses a wide overview of the characteristics, preparations, pre-treatment and application of bare PGE and in combination with other modifier as electrochemical sensors for the quantification of organic pollutants specifically pharmaceuticals and pesticides.

    更新日期:2019-09-18
  • Multi-Physics Coupling Analysis on the Time-Dependent Localized Corrosion Behavior of Carbon Steel in CO2-H2O Environment
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2019-09-06
    Kai Wang, Chenpei Li, Yanhui Li, Jinling Lu, Yueshe Wang, Xingqi Luo

    Localized corrosion of carbon steel in CO2-H2O environment is a long-standing challenge faced by the oil and gas industry, because of its unfeasible detection and high propagation rate. Numerical modelling can overcome the limitations of the spatial and temporal scales in the experimental studies, thus becoming a valuable complement. A multi-physics coupling model is established to investigate the evolution of localized corrosion of carbon steel in CO2 aqueous environment. The complex interactions among the kinetics of electrode reactions, multicomponent reactions, mass transfer and the deposition of corrosion products are coupled into the model, achieving a comprehensive and physically realistic description of the actual corrosion process. The arbitrary Lagrangian-Eulerian method is implemented to track the moving metal/solution interface. Special emphasis is put on the coupling mechanism among the underlying processes at different time and length scales. This study characterizes quantitatively the time-dependent corrosion behavior, including the distributions of potential and species concentration within the corroding pit, corrosion current density and pit morphology. The inherent relationship between the corrosion behavior and the local corrosive environment within the pit is revealed. The results indicate that the competition between the chemical effect and electrical effect determines the trend and distribution of corrosion current density. The pit shape and cathode/anode area ratio have a great influence on the corrosion behavior due to the coupled role of local solution chemistry and electrical field.

    更新日期:2019-09-06
  • Modeling Overcharge at Graphite Electrodes: Plating and Dissolution of Lithium
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2019-09-04
    Daniel R. Baker, Mark W. Verbrugge

    We derive and implement a set of equations that can be used to describe overcharge of a lithium ion cell, which can result in lithium (Li) plating on the graphite electrode. Graphite electrodes are the current material of the choice for the negative electrode (anode on discharge). We add two theoretical developments to published models to address Li plating. First, the existing models are not well-posed in terms of handling the Li deposition and dissolution electrochemical reactions. Second, the plated Li can interact directly with vacant sites in the graphite, which has not been treated in the literature, and which impacts the system response. With the inclusion of these new theoretical developments, and the use of our recently developed multi-site, multi-reaction (MSMR) formulation, we demonstrate the utility of the overcharge model and simulate relatively fast charging and discharging of a graphite electrode (i.e., at the 1C rate, yielding about 1 hour to fully charge or discharge the electrode) with a single-particle representation.

    更新日期:2019-09-04
  • How Transition Metals Enable Electron Transfer through the SEI: Part I. Experiments and Butler-Volmer Modeling
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2019-08-26
    Oliver C. Harris, Yuxiao Lin, Yue Qi, Kevin Leung, Maureen H. Tang

    Transition metal dissolution from high-voltage Li-ion battery cathodes disrupts the formation and performance of the solid-electrolyte interphase (SEI). SEI contamination by transition metals results in continual Li loss and severe capacity fade. Fundamental understanding of how metals undermine SEI passivation is necessary to mitigate this degradation. This two-part study interrogates the mechanisms by which transition metals facilitate through-film charge-transfer and SEI failure. Part I presents experimental results in which we intentionally contaminate SEIs with Mn, Ni, and Co. Rotating disk electrode voltammetry of a redox mediator quantifies how each metal impacts the charge-transfer characteristics of the SEI. A physics-based model finds that all three metals disrupt the electronic properties of the SEI more than the morphology. Surprisingly, the Butler-Volmer kinetics of charge-transfer through a Mn-contaminated SEI are an order of magnitude faster than for a Co-contaminated SEI, even with similar embedded metal concentrations. Such trends between metals are inconsistent with bandgap predictions from density functional theory, implying an alternative redox-cycling mechanism, which is mathematically developed and compared to experiment in Part II.

    更新日期:2019-08-27
  • How Transition Metals Enable Electron Transfer through the SEI: Part II. Redox-Cycling Mechanism Model and Experiment
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2019-08-26
    Oliver C. Harris, Kevin Leung, Maureen H. Tang

    At high operating voltages, metals like Mn, Ni, and Co dissolve from Li-ion cathodes, deposit at the anode, and interfere with the performance of the solid-electrolyte interphase (SEI) to cause constant Li loss. The mechanism by which these metals disrupt SEI processes at the anode remains poorly understood. Experiments from Part I of this work demonstrate that Mn, Ni, and Co all affect the electronic properties of the SEI much more than the morphology, and that Mn is the most aggressively disruptive of the three metals. In this work we determine how a proposed electrocatalytic mechanism can explain why Mn contamination is uniquely detrimental to SEI passivation. We develop a microkinetic model of the redox cycling mechanism and apply it to experiments from Part I. The results show that the thermodynamic metal reduction potential does not explain why Mn is the most active of the three metals. Instead, kinetic differences between the three metals are more likely to govern their reactivity in the SEI. Our results emphasize the importance of local coordination environment and proximity to the anode within the SEI for controlling electron transfer and resulting capacity fade.

    更新日期:2019-08-27
  • Quantitative Parameter Estimation, Model Selection, and Variable Selection in Battery Science
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2019-08-16
    Nicholas W. Brady, Christian Alexander Gould, Alan C. West

    Numerical physics-based models are useful in understanding battery performance and developing optimal battery design architectures. Data science developments have enabled software algorithms to perform data analysis and decision making that traditionally could only be performed by technical experts. Traditional workflows of model development - manual parameter estimation through visual comparison of simulations to experimental observations, and model discrimination through expert intuition - are time-consuming, and difficult to justify. This paper compares the conclusions derived from computationally scalable algorithms to conclusions developed by expert researchers. This paper illustrates how data science techniques, such as cross-validation and lasso regression, can be used to augment physics-based simulations to perform data analysis such as parameter estimation, model selection, variable selection, and model-guided design of experiment. The validation of these algorithms is that they produce results similar to those of the expert modeler. The algorithms outlined are well-established and the approaches are general, so can be applied to a variety of battery chemistries and architectures. The conclusions reached using these approaches are in agreement with expert analysis (literature results), were reached with minimal human intervention, and provide quantitative justification. By minimizing the amount of expert time, and providing rigorous quantitative justifications, these methods may accelerate battery development.

    更新日期:2019-08-16
  • Langmuir-Blodgett Assembly of Carboxylic Multiwalled Carbon Nanotubes-Nafion for Amperometric Sensing of Codeine
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2019-08-14
    Yanju Wu, Zijing Liu, Shihao Zhou, Fei Wang, Can Zhang, Kui Lu

    In this work, Langmuir−Blodgett (LB) technique was proposed to assemble the homogeneous and controlled films of carboxylic multiwalled carbon nanotubes-Nafion (c-MWCNTs-Nafion). Microstructure and electrochemical performance of LB films of c-MWCNTs-Nafion were characterized by AFM, SEM and electrochemical experiments. Moreover, the LB film of c-MWCNTs-Nafion was transferred to the surface of glassy carbon (GC) electrode to fabricate the electrochemical voltametric and amperometric sensor for codeine. The fabricated sensor showed enhanced electrocatalytic behavior for the oxidation of codeine. The amperometric currents for codeine are proportional to its concentration in a range from 1.0 × 10−7 to 1.0 × 10−5 mol L−1 with a detection limit of 3.0 × 10−8 mol L−1. And the proposed method exhibited good repeatability, stability, selectivity and accuracy.

    更新日期:2019-08-15
  • Coupling Enhanced Oxygen Reduction Reaction Activity from Ag Nanorods-rGO Hybrids
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2019-08-13
    Dong-Xiang Zhu, Shuai Chen, Jian-Li Mi, Chen-Xi Xu, Pai-Feng Luo, Ji-Gui Cheng, Hong-Hai Zhong, Ying-Wei Lu

    Ag nanorods-reduced graphene oxide (Ag-rGO) hybrid nanostructures, as an alternative oxygen reduction catalyst to Pt-based materials, have been prepared through a co-reductive method. The electrochemical performance reveal that both the on-set potentials and the limiting diffusion current densities of Ag-rGO samples are comparable to those of commercial Pt/C catalyst, implying that such hybrid nanostructures could be employed in alkaline fuel cells. Both contrast experimental characterizations and energy level analysis indicate that the enhanced oxygen reduction activity of Ag-rGO hybrid nanostructures can be attributed to the strong coupling between Ag nanorods and rGO sheets.

    更新日期:2019-08-15
  • Effect of Boron Distribution on the Intergranular Corrosion Resistance of UNS S32506 Duplex Stainless Steels
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2019-08-14
    Takayuki Takei, Murotsune Yabe, Azusa Ooi, Eiji Tada, Atsushi Nishikata

    The effect of boron distribution on the intergranular corrosion (IGC) resistance of UNS S32506 duplex stainless steel (DSSs) was investigated. IGC tests in boiling nitric acid were conducted with DSSs with boron contents ranging from 1 to 50 ppm. The corrosion rate increased with increasing boron addition. Further addition of boron did not affect the IGC resistance. Microstructural observations, corrosion depth measurements, and secondary-ion mass spectrometry analysis revealed that the diminished IGC resistance was attributable to corrosion resistance degradation of α/γ interfaces due to boron segregation at the interfaces.

    更新日期:2019-08-14
  • Electrochemical Deposition of Erbium on a Binary Al-Zn Cathode
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2019-08-14
    Hao Ren, Yalan Liu, Taiqi Yin, Zixuan Deng, Dawei Yang, Zhifang Chai, Keke Chang, Weiqun Shi

    In this work, the electrochemical behaviors of Er(III) on different kinds of electrode materials (W and liquid Al-Zn cathode), as a representative of lanthanides (Lns), were studied systematically by various electrochemical techniques. This opened the door toward the development of active electrode materials for recovering actinides (Ans) over Lns in chloride molten salts. Compared to the direct deposition of Er metal on an inert cathode, the reduction of Er(III) occurs at more anodic potentials via forming binary or ternary intermetallic compounds in both co-reduction and under potential deposition processes. In addition, potentiostatic and galvanostatic electrolysis were both conducted to confirm the formation of intermetallics, and some typical related intermetallic compounds were identified by X-ray diffraction (XRD) characterization. The morphology and composition of Er-Al-Zn ternary alloys were investigated using scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS).

    更新日期:2019-08-14
  • Competitive Effect of Leveler's Electrochemical Behavior and Impurity on Electrical Resistance of Electroplated Copper
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2019-08-14
    Zhaoyang Zhang, Yunwen Wu, Yumei Zhang, Tao Hang, Anmin Hu, Huiqin Ling, Ming Li

    Leveler is one of the crucial factors to fabricate electroplated Cu with excellent electrical property in advanced interconnect metallization. Little attention has been paid on the effects of leveler on the electrical resistance of electroplated Cu during self-annealing. In this study, the impacts of three different levelers on the sheet resistance of the electrochemical deposited Cu films are studied in terms of microstructure, impurity and electrochemical behavior. Three levelers show differences in inhibition ability on Cu deposition and levels of impurities introduced into Cu films, the former influences the original crystal grain size. The driving force originated from grain boundaries and hinder effect of impurities are two opposite factors which work competitively for grain growth. This study shows the direct evidence on the impacts of the two opposite factors on the resistance performance of deposited Cu films during self-annealing. We find that the leveler with the strongest inhibitory ability and a reasonable level of introduced impurities shows the largest resistance drop during recrystallization process, indicating the considerable improved conductivity. We believe this work will provide a scientific basis for the selection of levelers to obtain the Cu films with excellent electrical property and microstructure in electronic industrial applications.

    更新日期:2019-08-14
  • Suppression of Copper Electrodeposition by PEG in Methanesulfonic Acid Electrolytes
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2019-08-13
    Ryan T. Rooney, Himendra Jha, Dirk Rohde, Ralf Schmidt, Andrew A. Gewirth

    We investigate the suppression behavior of poly(ethylene glycol) (PEG) in methanesulfonic acid (MSA) Cu plating baths using electrochemical methods, normal Raman spectroscopy, surface-enhanced Raman spectroscopy (SERS), and electrochemical quartz crystal microbalance (QCM) measurements. Suppression of Cu electrodeposition by PEG in H2SO4 electrolytes only occurs in the presence of Cl−, whereas Cl− is not required in MSA electrolytes. SERS measurements of MSA electrolytes without PEG at a Cu surface show MSA molecules undergo a re-orientation at ca. −0.15 V vs. Ag/AgCl, as evidenced by potential-dependent symmetry changes. The re-orientation of MSA in MSA + PEG electrolyte does not occur until −0.3 V vs. Ag/AgCl. At potentials negative of −0.3 V, MSA re-orients and PEG leaves the surface, in coordination with onset of Cu reduction current, suggesting the suppression interaction of PEG at a Cu surface is facilitated by MSA. QCM measurements demonstrate a similar departure of PEG mass at potentials negative of the MSA re-orientation.

    更新日期:2019-08-14
  • The Behavior of Additives LiF, MgF2 and KF on Current Efficiency in Aluminium Electrolysis
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2019-08-13
    Peng Cui, Bo Qin, Geir Martin Haarberg

    The effects of LiF, MgF2 and KF additions to the electrolyte on current efficiency were investigated during aluminium electrolysis using base NaF−AlF3−Al2O3 system with a cryolite ratio of 2.5, 4% Al2O3 and 5% CaF2 at 980°C in laboratory scale. The duration of each electrolysis experiment was 4 h with a graphite anode and a cathodic current density of 0.85 Acm−2. The influences of various additives on the current efficiency of the aluminium electrolysis are compared. Additions of LiF up to 5 wt % were found to improve the current efficiency of aluminium deposition. Additions of MgF2 had a positive effect on current efficiency and KF addition was harmful for the current efficiency. Current efficiencies for aluminium deposition were obtained when the additions of LiF mixed together with the additions of KF and MgF2. The concentration of the alkali metals including K, Na and Li in deposited aluminium were analyzed as a function of the additives. Results are presented from a study of the influence of the additions on the cathode process. Correlations between the sodium content in aluminium with different additions and the current efficiency are discussed.

    更新日期:2019-08-14
  • Effects of Oxide Ions on the Electrodeposition Process of Silicon in Molten Fluorides
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2019-08-13
    Yuta Suzuki, Yosuke Inoue, Masayuki Yokota, Takuya Goto

    We studied the effects of O2− ions on the coordination structure of Si ions and the electrodeposition process of Si films in molten fluorides using SiO2 powder (as a source of Si) and Li2O (as a source of O2−). High-temperature Raman spectroscopic data revealed that the dissolution of SiO2 in molten KF, LiF-KF, and LiF-NaF-KF without Li2O was proceeded by the formation of silicate ions, with the [Si2O5]2− ion acting as the dominant species. On the other hand, when 3.0 mol% Li2O was added to molten LiF-KF and LiF-NaF-KF, the intensity of Raman band due to [SiO3F]3− ion was increased compared to that without Li2O system, which indicated that the O2− ions could cause breakage of Si-O-Si bonds of SiO2 or [Si2O5]2− ions. Furthermore, the reduction currents, attributed to the reduction of Si ions, increased significantly by the addition of Li2O; moreover, the thickness and current efficiency of the electrodeposited polycrystalline Si layer prepared by potentiostatic electrolysis was improved. These results indicated that the O2− ions can change the coordination structure of Si ions in molten fluorides and that the design of the molten salts bath is a key technology for fabricating high-quality Si layers with high current efficiency.

    更新日期:2019-08-14
  • Screening of Catalysts for the Electrochemical Oxidation of Organic Fuels in A Multi-Anode Proton Exchange Membrane Cell
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2019-08-13
    Tobias M. Brueckner, Evan Wheeler, Binyu Chen, Ehab N. El Sawy, Peter G. Pickup

    A multi-anode, proton exchange membrane electrolysis cell has been used to evaluate commercial and developmental catalysts for the oxidation of methanol, ethanol, ethylene glycol, and glycerol at 80°C. By operating the cell in crossover mode, with the fuel supplied to the cathode, steady-state mass transport limited currents can be achieved. This provides a measure of the stoichiometry of the reaction, which is controlled by the product distribution. The method has been benchmarked by using commercial PtRu black and carbon supported catalysts with 20% and 70% Pt. In all cases, the PtRu alloy decreased onset and half-wave potentials relative to Pt. However, stoichiometries for ethanol, ethylene glycol, and glycerol oxidation were greatly decreased by the presence of Ru. This effect was mitigated by employing Ru as the core in Ru@Pt nanoparticles or in a mixed Ru + Sn oxide support material. Although not as effective as the PtRu alloy for promoting low potential activity, these catalysts exhibited selectivity similar to Pt. Use of alloyed Rh and a Rh core was also evaluated, but did not show any benefits over Pt alone.

    更新日期:2019-08-14
  • Communication--Fracture Behavior of Single LiNi0.33Mn0.33Co0.33O2 Particles Studied by Flat Punch Indentation
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2019-08-13
    Dingying Dang, Yikai Wang, Yang-Tse Cheng

    The fracture of lithium nickel manganese cobalt oxide (NMC) particles can affect the electrochemical performance and manufacturing process of NMC electrodes. Here, we report the fracture behavior of single LiNi0.33Mn0.33Co0.33O2 (NMC111) secondary particles studied by flat punch indentation. The critical load corresponding to the fracture of NMC111 secondary particles increases with increasing particle size, while the fracture strength is unaffected by the size of the secondary particles. Particles at the first delithiation and lithiation states have significantly lower critical load and fracture strength than the pristine ones, suggesting that electrochemical cycling strongly affects the mechanical integrity of NMC111 secondary particles.

    更新日期:2019-08-14
  • Communication--Aluminum Doping in LiMnPO4 with an Unexpected Charge Compensation
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2019-08-13
    Wei Chen, Haisheng Fang

    Here a series of Al-doped LiMnPO4 with controlled cation ratios based on appropriate charge compensation mechanisms are synthesized and compared. The results suggest that Al3+ can be doped into the lattice of LiMnPO4 and the preferable doping mechanism is in a scheme of Li1-xAlxMnPO4 where Al3+ occupies Li+ site with charge compensation by electronic defect. Such a charge-compensation mechanism is much different from those previously reported and needs further study.

    更新日期:2019-08-14
  • Non-Enzymatic Electrochemical Determination of Progesterone Using Carbon Nanospheres from Onion Peels Coated on Carbon Fiber Paper
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2019-08-13
    Akshaya K. B., Vinay S. Bhat, Anitha Varghese, Louis George, Gurumurthy Hegde

    A simple electrochemical sensor was developed by coating Onion peel wastes derived carbon nanospheres on carbon fiber paper (CFP) electrode. Carbon nanospheres (CNS) were prepared from Onion peels utilizing an environmentally benign and cost-effective strategy. In the present investigation, the obtained carbon nanospheres were coated on carbon fiber paper and the modified electrodes were physicochemically characterized by Field emission scanning electron microscopy (FESEM) with energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) spectroscopy and X-ray photoelectron spectroscopy (XPS) techniques. Electrochemical characterizations of the modified electrodes were done by Cyclic voltammetry (CV) and Electrochemical impedance spectroscopy (EIS). CNS modified CFP electrode was successfully used in the determination of Progesterone, an important steroid hormone at an ultra-nanomolar level with superior detection limit of 0.012 nM. The developed electrochemical sensor was effectively utilized for the determination of Progesterone in pharmaceutical Progesterone injections, human blood serum samples and cow milk samples.

    更新日期:2019-08-14
  • Economical and Efficient Electrochemical Sensing of Folic Acid using a Platinum Electrode Modified with Hydrothermally Synthesized Pd and Ag Co-Doped SnO2 Nanoparticles
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2019-08-13
    Asha Sharma, Sandeep Arya

    In this work, an economical method of electrochemical sensing for the detection of Folic acid (FA) has been reported. A sol gel assisted hydrothermal technique was used to synthesize undoped, Ag doped and Pd-Ag co-doped, SnO2 nanoparticles. The structure, morphology, shape, and chemical composition of the synthesized nanoparticles were confirmed by XRD, FESEM, TEM, FTIR, and EDS spectroscopic techniques. Cyclic voltammetry (CV) and Differential pulse voltammetry (DPV) studies confirmed that Pd and Ag co-doped SnO2 nanoparticles show significant competency in sensing FA due to their high specific surface and excellent electrical conductivity. The platinum (Pt) electrode was modified with the synthesized nanoparticles to serve as a precise sensing agent. The resulting electrode showed viable sensing performance for detecting FA in a pharmaceutical sample with excellent recovery. The calibration plot is linear in the concentration range of 22 μM–112 μM and has a 3.47 μM detection limit. The assay is outstandingly reproducible, selective and stable.

    更新日期:2019-08-14
  • A Non-Enzymatic Glucose Sensor Based on the Hybrid Thin Films of Cu on Acetanilide/ITO
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2019-08-13
    Maryam Sajadpour, Hossein Siampour, Sara Abbasian, Masoud Amiri, Raffael Rameshan, Christoph Rameshan, Ali Hajian, Hasan Bagheri, Ahmad Moshaii

    A stable and sensitive non-enzymatic glucose sensor is proposed based on the hybrid thin films of copper on acetanilide/ITO-PET. The electrode was fabricated through a two-step synthesis process including electrochemical deposition of acetanilide on ITO-PET, subsequent by physical vapor deposition of a copper film. The electron microscopy images showed the formation of a porous structure on the ITO-PET sheet. Such modified electrode presents a high sensitivity of 59.95μAmM−1cm−2 with a low limit of detection of 1.501μM. This glucose sensor exhibits a range of linear response between 2 to 12mM. In addition, it includes a variety of advantages as high flexibility, the possibility for scale-up production, low material consumption, low cost, excellent reproducibility, high selectivity, good sensitivity and short response time. Finally, the glucose determination of different human blood serums indicates that the deviation of this sensor from the clinical measurements is less than 5%.

    更新日期:2019-08-14
  • Bromide Ion as a Leveler for High-Speed TSV Filling
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2019-08-12
    Minjae Sung, Young Yoon, Jinwoo Hong, Myung Jun Kim, Jae Jeong Kim

    Organic levelers have been essential additives for Cu electrodeposition to achieve defect-free filling of through-silicon vias (TSVs). They selectively inhibit Cu deposition on top of TSVs, avoiding the occlusion of TSV openings and concentrating Cu deposition inside the TSVs. We recently reported that iodide ions (I−) can act as an inorganic leveler to induce defect-free TSV filling. However, it was found that I− considerably decreased the efficiency of Cu electrodeposition because of the formation of an unstable CuI suppression layer on top of the wafer. The CuI layer easily detached from the wafer, and additional electrons were consumed to reestablish the suppression layer during gap-filling. This study introduces a TSV filling process with bromide ions (Br−) as an alternative to I−. Although the suppression strength of Br− to Cu electrodeposition is weaker than that of I−, Br− forms a more stable suppression layer that does not reduce the efficiency of Cu electrodeposition, enabling high-speed TSVs filling. As a result, the filling rate with Br− was twice as fast as that with I− at the same applied current density; thereby TSVs 60 μm deep and 5 μm in diameter were completely filled in 500 s.

    更新日期:2019-08-12
  • Correlative X-ray Tomographic Imaging of Catalyst Layer Degradation in Fuel Cells
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2019-08-12
    Robin T. White, Dilip Ramani, Sebastian Eberhardt, Marina Najm, Francesco P. Orfino, Monica Dutta, Erik Kjeang

    Effective catalyst layer design is vital for high-performing polymer electrolyte fuel cells. However, the desired catalyst layer structure may be compromised by operational degradation, causing performance decay. The present work investigates the multi-scale catalyst layer structure and properties across different stages of degradation, including liquid water distribution in an operating fuel cell. A correlative, multi-scale imaging workflow with a combined analysis by operando lab-based micro-X-ray computed tomography (XCT) and nano-XCT is developed for this purpose. From operando XCT results, the catalyst layer solid area fraction was found to gradually decrease by 25% with crack formation and severe localized corrosion accompanied by up to 50% thinning and significantly altered liquid water distribution. Localized degradation features such as nano-scale cracks and internal pore-size distribution changes were resolved using nano-XCT and tracked by 3+1D imaging at different stages of degradation. Porosity changes quantified by nano-XCT on the order of 40% from beginning-of-life to end-of-life with reduction in connected pore fraction were observed as well as increase in average pore size by 50%. The effect of changes at the nano-scale on diffusion properties were calculated and an empirical model is proposed for degraded catalyst layer structures where Knudsen effects are dominant.

    更新日期:2019-08-12
  • Influence of Gas Diffusion Media Compression on Open-Cathode Fuel Cells
    J. Electrochem. Soc. (IF 3.120) Pub Date : 2019-08-12
    Robert W. Atkinson III, Matthew W. Hazard, Joseph A. Rodgers, Richard O. Stroman, Benjamin D. Gould

    Open-cathode fuel cell power production increases significantly when gas diffusion media (GDM) compressive stress is increased to values greater than those recommended for forced-convection fuel cells by mitigating common shortcomings related to cell thermal and water management. Increasing GDM compression from 20% to 37% reduces cell contact resistances by an order of magnitude. This decreases ohmic resistance by 32% and increases current density by 31% at 0.6 V when GDM compression increases from 20% to 40%. Though the effect of GDM compression on contact and ohmic resistances is significant, higher compression also improves thermal management and cell hydration, which are quantified by decreasing cathode surface temperatures and lower charge transfer resistances. A disadvantage of increasing GDM compression is the onset of a rising mass transport resistance at the highest levels of GDM compression (37–40%). However, this effect is of secondary importance compared to the benefits of higher GDM compression on enhancing cell hydration and reducing ohmic resistance as higher GDM compression results in the greatest power production in all operating conditions tested.

    更新日期:2019-08-12
Contents have been reproduced by permission of the publishers.
导出
全部期刊列表>>
2020新春特辑
限时免费阅读临床医学内容
ACS材料视界
科学报告最新纳米科学与技术研究
清华大学化学系段昊泓
自然科研论文编辑服务
中国科学院大学楚甲祥
上海纽约大学William Glover
中国科学院化学研究所
课题组网站
X-MOL
北京大学分子工程苏南研究院
华东师范大学分子机器及功能材料
中山大学化学工程与技术学院
试剂库存
天合科研
down
wechat
bug