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  • Impact-activated Programming of Electro-Mechanical Resonators Through Ferroelectret NanoGenerator (FENG) and Vanadium Dioxide
    Nano Energy (IF 12.343) Pub Date : 2017-11-22
    Yunqi Cao, Wei Li, José Figueroa, Tongyu Wang, David Torres, Chuan Wang, Zhong Lin Wang, Nelson Sepúlveda

    Ferroelectret Nanogenerators (FENG) devices were introduced recently as promising flexible devices for energy harvesting and microphone/loud-speaker applications. Vanadium dioxide (VO2) thin films, on the other hand, have been demonstrated to enable large frequency tunability of miniaturized electro-mechanical structures, which are commonly integrated in transceiver and communication systems. In this work, we integrate these two technologies, to show a system where an electric pulse, supplied by the FENG can be used to tune the resonant frequency of VO2-based micro-electro-mechanical structures. Furthermore, due to the VO2's hysteretic behavior, the applied pulse also programs the tuned frequency, allowing for different frequency states in the device for a single applied DC bias. It is found that the tuning of the frequency states is determined by the supplied energy, and the programming is more efficient for larger, shorter pulses –even if the duration of the pulse is shorter than the system's thermal time constant. We explore two different mechanical structures, bridge and cantilever. A wider tuning range is found for the bridge structure (22%), which is due to the larger frequency sensitivity with stress for this configuration. The tuning/programming action uses harvested mechanical energy, which could come from the user. The potential use of the developed system as an accelerometer or impact sensor for monitoring brain injuries in contact-sports is discussed.

    更新日期:2017-11-23
  • All-organic microelectromechanical systems integrating electrostrictive nanocomposite for mechanical energy harvesting
    Nano Energy (IF 12.343) Pub Date : 2017-11-22
    Hussein Nesser, Hélène Debéda, Jinkai Yuan, Annie Colin, Philippe Poulin, Isabelle Dufour, Cédric Ayela

    Recent advances in the field of microelectromechanical systems (MEMS) have generated great interest in the substitution of inorganic microcantilevers by organic ones, due to their low cost, high flexibility and a simplified fabrication by means of printing methods. Here, we present the integration of electrostrictive nanocomposites into organic microcantilever resonators specifically designed for mechanical energy harvesting from ambient vibrations. Strain sensitive nanocomposite materials composed of reduced graphene oxide (rGO) dispersed in polydimethylsiloxane (PDMS) are integrated into all-organic MEMS by means of an innovative low-cost and environment friendly process by combining printing techniques and xurography. Static tests of the electrostrictive nanocomposite with 3.7 wt% rGO show good performances with variations of capacitance that exceeds 4% for strain values lower than 0.55% as the microcantilever is bent. The results in dynamic mode suggest that the organic MEMS meet the requirements for vibration energy harvesting. With an applied sinusoidal acceleration (amplitude 0.5 g, frequency 15 Hz) a power density of 6μW/cm3 is achieved using a primitive circuit.

    更新日期:2017-11-22
  • Significantly Improving Cycling Performance of Cathodes in Lithium Ion Batteries: The Effect of Al2O3 and LiAlO2 Coatings on LiNi0.6Co0.2Mn0.2O2
    Nano Energy (IF 12.343) Pub Date : 2017-11-21
    Wen Liu, Xifei Li, Dongbin Xiong, Youchen Hao, Jianwei Li, Huari Kou, Bo Yan, Dejun Li, Shigang Lu, Alicia Koo, Keegan Adair, Xueliang Sun

    LiNi0.6Co0.2Mn0.2O2 (NCM) is a highly potential cathode material for lithium-ion batteries (LIBs). However, its poor rate capability and cycling performance at high cutoff voltages have seriously hindered further commercialization. In this study, we successfully design an ultra-thin lithium aluminum oxide (LiAlO2) coating on NCM for LIBs. Compared to Al2O3, the utilization of lithium-ion conducting LiAlO2 significantly improves the NCM performance at high cutoff voltages of 4.5/4.7 V. The study reveals that the LiAlO2-coated NCM can maintain a reversible capacity of more than 149 mA h g−1 after 350 cycles with 0.078% decay per cycle. Furthermore, LiAlO2-coated NCM exhibits higher rate capacities [206.8 mA h g−1 at 0.2 C (50 mA g−1) and 142 mA h g−1 at 3 C] than the Al2O3-coated NCM (196.9 mA h g−1 at 0.2 C and 131.9 mA h g−1 at 3 C). Our study demonstrates that the ultra-thin LiAlO2 coating is superior to Al2O3 and significantly improves the capacity retention and rate capability of NCM for LIBs.

    更新日期:2017-11-22
  • Ultrahigh Electrocatalytic Oxygen Evolution by Iron-Nickel Sulfide Nanosheets/ Reduced Graphene Oxide Nanohybrids with an Optimized Autoxidation Process
    Nano Energy (IF 12.343) Pub Date : 2017-11-21
    Jun Jiang, Shu Lu, Wei-Kang Wang, Gui-Xiang Huang, Bao-Cheng Huang, Feng Zhang, Ying-Jie Zhang, Han-Qing Yu

    Iron-nickel-based electrocatalysts are a group of noble-metal-free and high-performance candidate for oxygen evolution reaction (OER), and autoxidation always occurs in their OER process. Autoxidation is a double-edged sword: it could in-situ generate high-catalytic activity sites to accelerate OER, but it also results in the attenuation of conductivity and the dissolution of active components. In this work, we propose a new strategy to relieve the negative impacts of autoxidation on OER through designing three-dimensional (3D) iron-nickel sulfide nanosheets/reduced graphene oxide (FeNiS2 NS/rGO) nanohybrids via a one-pot colloidal method, which enabled the well dispersion and strong coupling of FeNiS2 NS on the rGO. Such an interconnected 3D architecture could facilitate excellent electron transport, provide large amounts of active sites and prevent the dissolution of active components. The FeNiS2 NS/rGO delivered extremely low overpotentials of 270 mV and 200 mV to reach a current density of 10 mA cm−2, and rapid kinetics with Tafe slope of 38 mV dec−1 and 40 mV dec−1 for OER in 0.1 and 1.0 M KOH, respectively. Moreover, they could retain a great stability without activity loss over long-term continuous electrolysis and long-ageing time under air conditions. This work provides an efficient approach to resolve the autoxidation problem of FeNiS2 NS in the OER process and develops a promising earth-abundant OER electrocatalyst towards practical applications.

    更新日期:2017-11-22
  • High Thermoelectric Performance of Few-Quintuple Sb2Te3 Nanofilms
    Nano Energy (IF 12.343) Pub Date : 2017-11-21
    Zhen Li, Naihua Miao, Jian Zhou, Zhimei Sun, Zikui Liu, Huibin Xu

    Antimony telluride (Sb2Te3) has a very low ZT ZT value at room temperature, even though the alloys of Bi2Te3 and Sb2Te3 are the most widely used thermoelectric materials. Taking advantage of nano-structures and topological insulators (TIs), we report that high ZT ZT values of larger than 2 can be achieved in one quintuple-layer (QL, ZT ZT ≥ ≥ 2.1) and 4 QLs (ZT ZT ≥ ≥ 2.2) of Sb2Te3 at room temperature, while the ZT ZT value for bulk is around 0.5. For 1 QL, Seebeck coefficient has been greatly enhanced due to the increase in the number of band extrema by virtue of the twelvefold valley degeneracy from surface states. For 4 QLs, the high ZT ZT value is attributed to the much longer surface relaxation time associated with the robust nature of the topological surface states. Moreover, the ZT ZT values and the TI character of few-quintuple Sb2Te3 nanofilms demonstrate thickness(layer)-dependent behaviors. Our results offer significant clues for future applications and investigations of Sb2Te3-related quintuple layers as promising p-type thermoelectric materials and quasi-2D topological insulators for nanoelectronics.

    更新日期:2017-11-22
  • Triboelectric-Piezoelectric-Electromagnetic Hybrid Nanogenerator for High-Efficient Vibration Energy Harvesting and Self-powered Wireless Monitoring System
    Nano Energy (IF 12.343) Pub Date : 2017-11-21
    Jian He, Tao Wen, Shuo Qian, Zengxing Zhang, Zhumei Tian, Jie Zhu, Jiliang Mu, Xiaojuan Hou, Wenping Geng, Jundong Cho, Jianqiang Han, Xiujian Chou, Chenyang Xue

    Energy harvesting is a key technology for the self-powered mode of wireless sensor nods and mobile terminals. A large number of devices have been developed to convert mechanical energy into electrical energy. Whereas great efforts have been made to improve the output performance, problems like energy dissipation, device life and response range still need to be addressed. Herein, we report a hybridized triboelectric-piezoelectric-electromagnetic nanogenerator efficiently harvesting vibration energy. Three harvest modes are integrated into a single device, whose core component is a magnetic levitation structure. On the one hand, it presents higher sensitivity than conventional spring or cantilever designs due to low energy loss, which favors the tiny energy harvesting like the slapping desk vibration and the running car vibration. On the other hand, the mechanical fatigue or damage can be avoided by the special structure design. Under 20Hz, triboelectric nanogenerator (TENG) can deliver a peak output power of 78.4μW, while the top (EMG2) and the bottom (EMG1) electromagnetic generator can provide a peak output power of 36mW and 38.4mW, respectively. Piezoelectric generator located at top (PEG2) and bottom (PEG1) can contribute a peak output power of 122 mW and 105mW, respectively. The capacitor charge measurement reveals that unit combination performance is remarkably stronger than individual performance, and the combination of TENG+EMG1+EMG2+PEG1+PEG2 has the highest energy harvesting capacity. Finally, this device has been integrated into a wireless sensor system. Results show that the wireless sensor system can be activated and transmit temperature and vibration signal to control computer. This work has a vital significance to the development and application of the internet of things.

    更新日期:2017-11-21
  • Atomic Layer Deposition-Enabled Ultrastable Freestanding Carbon-Selenium Cathodes with High Mass Loading for Sodium-Selenium Battery
    Nano Energy (IF 12.343) Pub Date : 2017-11-21
    Dingtao Ma, Yongliang Li, Jingbo Yang, Hongwei Mi, Shan Luo, Libo Deng, Chaoyi Yan, Peixin Zhang, Zhiqun Lin, Xiangzhong Ren, Jianqing Li, Han Zhang

    Melt diffusion followed by vapor deposition is judiciously combined with atomic layer deposition (ALD) to construct Al2O3–coated (Se/porous N-doped carbon nanofibers)@Se composite (denoted SC@Se-Al2O3) materials for sodium-selenium (Na-Se) batteries. High mass loading, ultrastable and free-standing carbon-selenium cathode is conveniently achieved by tailoring both the Se content and the thickness of deposited Al2O3 layer. Importantly, in contrast to only 176 mAh g-1 of the electrode without Al2O3 deposition after 660 cycles, the composite with a Se content of 67 wt% and a 3-nm Al2O3 thickness retains a reversible capacity of 503 mAh g-1 after 1000 cycles with no capacity fading at 0.5 A g-1. These findings clearly suggest that ALD strategy provides a viable, controllable and effective means of tuning the electrode performance towards high mass loading of active materials and long cycle life of the resulting battery for energy storage applications.

    更新日期:2017-11-21
  • Fundamental Understanding and Rational Design of High Energy Structural Microbatteries
    Nano Energy (IF 12.343) Pub Date : 2017-11-21
    Yuxing Wang, Qiuyan Li, Samuel Cartmell, Huidong Li, Sarah Mendoza, Ji-Guang Zhang, Zhiqun Daniel Deng, Jie Xiao

    Microbatteries play a critical role in determining the lifetime of downsized sensors, wearable devices, medical applications, and animal acoustic telemetry transmitters among others. More often, structural batteries are required from the perspective of aesthetics and space utilization, which is however rarely explored. Herein, we discuss the fundamental issues associated with the rational design of practically usable high energy microbatteries. The tubular shape of the cell further allows the flexible integration of microelectronics. A functioning acoustic micro-transmitter continuously powered by this tubular battery has been successfully demonstrated. Multiple design features adopted to accommodate large mechanical stress during the rolling process are discussed providing new insights in designing the structural microbatteries for emerging technologies.

    更新日期:2017-11-21
  • Rapidly Catalysis of Oxygen Evolution through Sequential Engineering of Vertically Layered FeNi Structure
    Nano Energy (IF 12.343) Pub Date : 2017-11-20
    Gong Zhang, Guichang Wang, Huijuan Liu, Jiuhui Qu, Jinghong Li

    For practical hydrogen (H2) production via water electrolysis, large-scale design and fabrication of catalysts for high-efficiency electrochemical transformation of hydroxyl ions to oxygen in alkaline environment is of paramount importance to reduce energy losses. Using anodization, electroplating, and sequential electrodeposition, we herein realized a universal approach to vertically assemble 2D Fe-Ni hydroxide nanosheets on nickel foam surface as catalyst for oxygen evolution reaction (OER). The electrode exhibited OER onset overpotentials (η) of ~190 mV and a low η of ~270 mV at a current density of 100 mA cm−2 in KOH electrolyte, making it one of the most active OER catalysts reported so far. The FeNi films deposited via sequential deposition are highly ordered, and electrode is stable even under long term or large current density operation. Based on the results of theoretical calculation, dielectric force microscopy (DFM) analysis, and capacitance measurements, we found that 2D Fe-Ni hydroxide -loaded electrode with enhanced conductivity facilitates the sufficiently conversion of active sites and ensures optimal adsorption energies for intermediates of OER, as a result of structural effects as well as introduction of optimal amount of Fe on surface.

    更新日期:2017-11-20
  • LiFePO4 Quantum-Dots Composite Synthesized by a General Microreactor Strategy for Ultra-high-rate Lithium Ion Batteries
    Nano Energy (IF 12.343) Pub Date : 2017-11-20
    Bo Wang, Ying Xie, Tong Liu, Hao Luo, Bin Wang, Chunhui Wang, Lei Wang, Dianlong Wang, Shixue Dou, Yu Zhou

    Due to the relatively slow, diffusion-controlled faradaic reaction mechanisms of conventional LiFePO4 (LFP) materials, which is hard to deliver satisfied capacity for high rate applications. In this work, ultrafine LFP quantum dots (LFP-QDs) co-modified by two types of carbonaceous materials - amorphous carbon and graphitized conductive carbon (graphene) have been successfully synthesized through a novel microreactor strategy. Because of the very limited area constructed by the dual-carbon microreactor for the growth of LFP crystal, it's demension was furthest suppressed to a very small level (~ 6.5 nm). Such a designed nano-composite possesses a large specific surface area for charge adsorption and abundant active sites for faradaic reactions, as well as ideal kinetic features for both electron and ion transport, and thus exhibits ultra-fast, surface-reaction-controlled lithium storage behavior, mimicking the pseudocapacitive mechanisms for supercapacitor materials, in terms of extraordinary rate capability (78 mAh g−1 at 200 C) and remarkable cycling stability (~ 99% over 1000 cycles at 20 C). On the other side, due to the quasi-2D structure of the synthesized LFP-QDs composite, which can be used as the basic unit to further fabricate free-standing film, aerogel and fiber electrode without the addition of binder and conductive agent for different practical applications. In addition, to deeper understand its electrochemical behavior, a combined experimental and density functional theoretical (DFT) calculation study is also introduced.

    更新日期:2017-11-20
  • All-inorganic flexible piezoelectric energy harvester enabled by two-dimensional mica
    Nano Energy (IF 12.343) Pub Date : 2017-11-20
    Ding Wang, Guoliang Yuan, Gengqian Hao, Yaojin Wang

    A rapid surge in the research on self-powered bio-electronics is occurring toward the challenge that the state-of-the-art bio-devices require obsolete bulky batteries, which limit device miniaturization and lifespan. Among them, flexible piezoelectric materials that enable mechanical-to-electrical energy conversion, stimulate tremendous attraction to harvest mechanical energy from the motions of human and organs. Here, we report a cost-effective one-step process based on unique two-dimensional mica substrates to fabricate flexible piezoelectric energy harvesters, extending beyond prior art for all-inorganic flexible piezoelectric materials. As an exemplary demonstration, an all-inorganic, large scale, flexible piezoelectric Pb(Zr0.52Ti0.48)O3 energy harvester is fabricated with an outstanding performance (i.e., open-circuit voltage of 120 V, short-circuit current density of 150 μA cm-2 and power density of 42.7 mW cm-3), which are comparable to those via conventional “grow-transfer” technique from rigid substrates to organic soft ribbons, and are much greater by one to four orders of magnitude than previous reported ones based on piezoelectric nanofibers and organic thick films. In particular. This unique process provides a new perspective to fabricate all-inorganic piezoelectric energy harvesters for battery-free bio-electronics.

    更新日期:2017-11-20
  • Grain boundary transport in sputter-deposited nanometric thin films of lithium manganese oxide
    Nano Energy (IF 12.343) Pub Date : 2017-11-20
    Juliane Mürter, Susann Nowak, Efi Hadjixenophontos, Yug Joshi, Guido Schmitz

    The lithium intercalation into ion-beam sputter-deposited films of lithium manganese oxide is studied as a function of the film thickness (50 nm to 500 nm). The kinetics of the intercalation is quantified in cyclic voltammetry under variation of the scanning rate over five orders of magnitude (0.005 mV/s to 768 mV/s). With an increasing rate, the intercalation currents reveal a transition from a finite length diffusion to a semi-infinite diffusion behavior, as it is expected from continuum transport equations. But surprisingly, the peak current in the Randles-Sevcik regime scales with the square root of film thickness. Consequently, the diffusion coefficient apparently increases with the layer thickness. Combining the parameters of the actual microstructure of the thin films with an appropriate kinetic modeling that includes the effects of grain boundaries, it is shown that the observed acceleration is quantitatively understood by outstandingly fast short-circuit transport in a type B kinetic regime of grain boundary diffusion.

    更新日期:2017-11-20
  • NiO-induced synthesis of PdNi bimetallic hollow nanocrystals with enhanced electrocatalytic activities toward ethanol and formic acid oxidation
    Nano Energy (IF 12.343) Pub Date : 2017-11-20
    Zelin Chen, Jinfeng Zhang, Yuan Zhang, Yunwei Liu, Xiaopeng Han, Cheng Zhong, Wenbin Hu, Yida Deng

    Noble-metal hollow nanocrystals possess numerous unique advantages such as high surface-to-volume ratio and high utilization of noble metals, which make them a promising electrocatalyst for electro-oxidation of small molecules in fuel cells. Herein, we prepared bimetallic PdNi hollow nanocrystals (PdNi-HNCs) by taking advantage of the galvanic replacement reaction in an aqueous solution and developed a facile NiO-induced strategy for the controlled synthesis of PdNi-HNCs with dendritic or smooth outer shell architectures. A very short oxidation time of an amorphous Ni template is demonstrated to be the key factor to successful fabrication of the dendritic morphology. The results of electrochemical testing indicate that the electrocatalytic activities of PdNi-HNCs are highly dependent on their morphologies. The PdNi-HNCs with a rough and dendritic shell exhibit a mass activity of 1201.5 and 768.0 mA·mgPd−1 toward ethanol oxidation reaction (EOR) and formic acid oxidation reaction (FAOR), respectively, much greater than those of the commercial Pd black catalyst (502.6 and 266.3 mA·mgPd−1, respectivlely). In particular, the 1500 cyclic voltammetry cycles in alkaline solution and the 30000 s chronoamperometry tests in acid solution suggest an enhanced long-term durability of PdNi-HNCs with dendritic nanoarchitectures. We ascribe the better catalytic activity to the hollow feature, higher specific electrochemical surface area, more abundant active sites and more appropriate electronic structure of the PdNi-HNCs with a rough and dendritic shell.

    更新日期:2017-11-20
  • A self-powered 2D barcode recognition system based on sliding mode triboelectric nanogenerator for personal identification
    Nano Energy (IF 12.343) Pub Date : 2017-11-16
    Jie Chen, Xianjie Pu, Hengyu Guo, Qian Tang, Li Feng, Xue Wang, Chenguo Hu

    Triboelectric nanogenerator (TENG) for developing self-powered personal identification system exhibits great advantages, however, some problems (swiping speed, stability, etc.) in the previous research work prevent this kind of barcode system for further applications. Herein, in this paper, we design a triboelectric based barcode recognition system (T-BS) for practical applications. By using a reference barcode component, the output signal under random swiping motion can be easily recognized, which offers an excellent strategy for the solution of the problems in the previous work. Through the conjunction of threshold value, phase difference and peak-searching, the output voltage signals of the device can be converted into digital signal “1” or “0”, and the coded information can be real-time displayed on LabVIEW platform. When swiping a card at a constant speed, or non-uniform speed by human hands, the coded information can be successfully identified and the access control system operates accurately. Moreover, by increasing the numbers of barcode columns and minifying the size, more precise 2D barcode recognition system (including barcode and reader) is obtained and realized the personal identification. This work demonstrates the possibility of the sliding mode TENG as a self-powered 2D barcode recognition system for personal identification, which indicates potential applications in information security.

    更新日期:2017-11-20
  • Carbon Paper Interlayers: A Universal and Effective Approach for Highly Stable Li Metal Anodes
    Nano Energy (IF 12.343) Pub Date : 2017-11-15
    Yang Zhao, Qian Sun, Xia Li, Changhong Wang, Yipeng Sun, Keegan R. Adair, Ruying Li, Xueliang Sun

    Li metal anode is considered as one of the most promising candidate for next generation Li metal batteries (LMBs) due to the unique properties of high specific capacity, low potential and light weight. However, the crucial problems, including serious Li dendrite growth, undesired side reactions and infinite volume changes, are still big challenges for Li metal anode, which can not only lead to the low Coulombic efficiency, but also can create short circuit risks. In this paper, we propose a novel and universal approach to achieve long life time and dendrite free Li metal anodes by introducing carbon paper (CP) as an interlayer. As a result, the as-designed electrodes can deliver extremely high capacity (up to 3 mAh cm−2 and 5 mAh cm−2), superior stable performances (620 h/265 cycles with 3 mAh cm−2) and high operational current densities (3 mA cm−2 and 5 mA cm−2). Meanwhile, the electrodes also can demonstrate high capacity and long life time in full cells using carbon-coated LiFePO4 (C/LiFePO4) as the cathode for lithium ion batteries (LIBs) and molecular layer deposition (MLD) coated C/S as cathode for Li-S batteries. These new understandings could open a new window for the fabrication of safe, long life time and dendrite-free Li metal anodes.

    更新日期:2017-11-17
  • Optoelectronic modeling of the Si/α-Fe2O3 heterojunction photoanode
    Nano Energy (IF 12.343) Pub Date : 2017-11-14
    Li Chen, Shaolong Wu, Dong Ma, Aixue Shang, Xiaofeng Li

    In photoelectrochemical (PEC) water-splitting systems, photoelectrode configuration is a key ingredient to obtain the high conversion efficiency. To effectively guide the device fabrication, the intrinsic multi-domain physics and mechanisms (e.g., light absorption in optical domain and carrier generation/separation/transport/collection in electrical domain) have to be uncovered, which requires the advanced optoelectronic simulation. In this study, focusing on the Si/α-Fe2O3 heterojunction photoanodes, we present a comprehensive optoelectronic study on the microscopic photoelectric processes inside the dual-absorbable photoanode. We systematically simulate the carrier generation, separation, recombination, and collection of the electron-hole pairs so that the complete optoelectronic responses of this kind of electronic devices can be obtained. The systems under consideration include n-Si/α-Fe2O3/electrolyte, p-Si/α-Fe2O3/electrolyte, and α-Fe2O3/electrolyte systems in order to uncover the intrinsic physics as well as find the optimal device designs. We obtain the spectra of light absorption, output- and recombination-photocurrent profiles, along with the current-voltage characteristics under dark and illumination conditions. Moreover, the energy band diagram under various system configurations are calculated and compared. The optoelectronic simulation and investigation provide a convenient methodology for the design of PEC-related systems for improved performance.

    更新日期:2017-11-15
  • ZnO/ZnFe2O4/N-doped C Micro-polyhedrons with Hierarchical Hollow Structure as High-Performance Anodes for Lithium-Ion Batteries
    Nano Energy (IF 12.343) Pub Date : 2017-11-14
    Yuan Ma, Yanjiao Ma, Dorin Geiger, Ute Kaiser, Huang Zhang, Guk-Tae Kim, Thomas Diemant, R. Jürgen Behm, Alberto Varzi, Stefano Passerini

    In this work, a facile and potentially scalable self-template synthesis of bi-component ZnO/ZnFe2O4/N-doped C micro-polyhedrons with hierarchical hollow structure (ZZFO-C) is presented. These are obtained through calcination of a single bi-metallic metal-organic framework (MOF) precursor (ZIF-ZnFe, molar ratio of 3:1). The resulting material shows a high surface area and is constituted by the organized assembly of numerous nanoparticles sub-unit (with size in the range of 20 nm). By tuning the annealing conditions, porous ZnO/ZnFe2O4 (ZZFO) micro-polyhedrons are obtained. The ZZFO-C composite materials are studied as anodes for LIBs exhibiting remarkable energy storage performance, such as, large reversible capacity (ca. 1000 mAh g−1 after 100 cycles at 200 mA g−1), excellent rate capability and cycling stability. After high-rate capacity testing (1000 cycles at 2.0 A g−1), ZZFO-C shows an excellent reversible capacity of 620 mAh g−1. The excellent performance of ZZFO-C arises from its unique hierarchical hollow structure and the synergy between the two active components and the N-doped carbon matrix. The electrochemical reaction mechanism and structure phase changes upon the initial lithiation are identified via in situ X-ray diffraction studies.

    更新日期:2017-11-15
  • Understanding the initial irreversibility of metal sulfides for sodium-ion batteries via operando techniques
    Nano Energy (IF 12.343) Pub Date : 2017-11-13
    Liguang Wang, Jiajun Wang, Fangmin Guo, Lu Ma, Yang Ren, Tianpin Wu, Pengjian Zuo, Geping Yin, Jun Wang

    Transition metal sulfides are promising high capacity anode materials for sodium-ion batteries in terms of the conversion reaction with multiple electron transfers. Nonetheless, some inherent challenges such as sluggish sodium ion diffusion kinetics, large volume change and poor cycle stability limit their implementation. Addressing these issues necessitates a comprehensive understanding on the complex sodium ion storage mechanism especially at the initial cycle. Here, taking nickel subsulfide as a model material, we reveal the complicated conversion reaction mechanism upon the first cycle by combining in operando 2D transmission X-ray microscopy with X-ray absorption spectroscopy, ex-situ 3D nano-tomography, high-energy X-ray diffraction and electrochemical impedance spectroscopy. This study demonstrates that the microstructure evolution, inherent slow sodium ion diffusion kinetics, and slow ion mobility at the two-phase interface contribute to the high irreversible capacity upon the first cycle. Such understandings are critical for developing the conversion reaction materials with the desired electrochemical activity and stability.

    更新日期:2017-11-14
  • Direct observation of spontaneous polarization induced electron charge transfer in stressed ZnO nanorods*
    Nano Energy (IF 12.343) Pub Date : 2017-11-11
    Masoud Seifikar, Björn P. Christian, János Volk, János Radó, István E. Lukács, Rolanas Dauksevicius, Rimvydas Gaidys, Vadim Lebedev, Antoine Viana, Eoin P. O'Reilly

    We report here a theoretical and experimental study of the charge generated when a ZnO nanorod is subjected to external force and contacting on a timescale of order seconds. We show, for the samples considered, that the measured charge flow is over four orders of magnitude larger than expected based on the strain-induced piezoelectric response, and is comparable in magnitude to the spontaneous charge on the surface of an ideal nanorod. We present a defect-mediated electrostatic model to explain how the measured charge transfer can arise from the nanorod spontaneous polarization induced electron charge.

    更新日期:2017-11-13
  • 16% Efficient Silicon/Organic Heterojunction Solar Cells using Narrow Band-Gap Conjugated Polyelectrolytes Based Low Resistance Electron-Selective Contacts
    Nano Energy (IF 12.343) Pub Date : 2017-11-11
    Jian He, Wenjun Zhang, Jichun Ye, Pingqi Gao

    Dopant-free silicon (Si)/organic heterojunction solar cells (HSCs) have drawn much attention due to their immense potential in achieving high power conversion efficiencies (PCEs) with simple device architectures and fabrication procedures. However, unsatisfied rear-contacts severely hinder further improvement in PCEs for these promising HSCs. Exploring effective cathodic interfacial materials with low temperature fabrication to replace conventional diffusion layer shows the extremely importance of technical innovation. Here, poly[4,8-bis(2-ethylhexyloxyl)benzo[1,2-b:4,5-b’]dithiophene-2,6-diyl-alt-ethylhexyl-3-fluorothieno[3,4-b]thiophene-2-carboxylate-4,6-diyl] (PTB7)-based narrow band-gap conjugated polyelectrolytes, PTB7-NBr and PTB7-NSO3, are firstly employed as effective cathodic interfacial materials in Si/organic HSCs to improve the passivation and electron transporting property at n-Si/Al interface. The low-temperature proceeded electron-selective contact of n-Si/PTB7-NBr/Al gives a contact resistivity as low as 6.7 ± 0.8 mΩ cm2, upon it a remarkable PCE of 16.0% is finally obtained from a completely dopant-free Si/organic HSC. The understanding of conjugated polyelectrolytes on interfacial modification may lead a path to fabricate high performance Si/organic heterojunction devices with efficient charge transfer process at a simplified fabrication process.

    更新日期:2017-11-13
  • Using a Synchronous Switch to Enhance Output Performance of Triboelectric Nanogenerators ☆
    Nano Energy (IF 12.343) Pub Date : 2017-11-11
    Paresh Vasandani, Bharat Gattu, Zhi-Hong Mao, Wenyan Jia, Mingui Sun

    Contact-mode triboelectric nanogenerators (TENGs) generally operate as a floating source with its two electrodes connected to an arbitrary external circuit forming a closed loop. In this paper, a switch based contact-mode TENG (SW-TENG) is presented, wherein a switch is placed between a TENG electrode and an external circuit. By electrically isolating the TENG from the external circuit when the switch is open, charge leakage is prevented and the output performance of the TENG is enhanced while the transferred tribocharges per cycle remain the same. Effect of different switching frequencies while keeping the contact-separation frequency (fcs) and contact force constant at 1 Hz and ~0.5 kgf, respectively, is presented. The versatility of the approach is presented via demonstrating the switching effect in three TENGs fabricated using different types of dielectric films – (a) bare PDMS, (b) microdome patterned PDMS, and (c) PDMS-Carbon nanofiber (CNF) composite. When the switching frequency (fsw) is in sync with fcs, the output voltage is increased by a factor of up to 22, 17, and 90, in SW-TENGs made using samples (a), (b), and (c), respectively, compared to that obtained under typical TENG operation. In a 1μF capacitor charging experiment, it has been shown that synchronous switching can prevent a charge leakage of up to approximately 60%. Further, a maximum area power density of 3.4 Wcm-2, 20 Wcm-2, and 31.7Wcm-2 is achieved at an external load resistance of 56Ω, in SW-TENGs made using samples (a), (b), and (c), respectively. Compared with a typical TENG, the optimal load resistance is decreased by six orders of magnitude, from megaohms to ohms. The SW-TENG thus provides a new approach for mechanical energy harvesting.

    更新日期:2017-11-13
  • Porous Cobalt Oxide Nanoplates Enriched with Oxygen Vacancies for Oxygen Evolution Reaction
    Nano Energy (IF 12.343) Pub Date : 2017-11-11
    Wenjing Xu, Fenglei Lyu, Yaocai Bai, Aiqin Gao, Ji Feng, Zhixiong Cai, Yadong Yin

    Porous cobalt oxide nanoplates enriched with oxygen vacancies are synthesized using a ligand-assisted polyol reduction method. This method enables large-scale synthesis that offers superior uniformity, solution dispersity and controllable concentration of oxygen vacancies on surface. The large surface area of porous cobalt oxide nanoplates together with enriched oxygen vacancies provide more active sites; which promotes faster exchange of intermediates and more efficient electron transfer. The as prepared cobalt oxide nanoplates manifest oxygen evolution reaction (OER) overpotential as low as 306 mV at 10 mA/cm2 in 1 M KOH, which is superior to the values of most reported Co-based electrocatalysts.

    更新日期:2017-11-11
  • A Photo-responsive Bifunctional Electrocatalyst for Oxygen Reduction and Evolution Reactions
    Nano Energy (IF 12.343) Pub Date : 2017-11-10
    Jiangquan Lv, Syed Comail Abbas, Yiyin Huang, Qin Liu, Maoxiang Wu, Yaobing Wang, Liming Dai

    Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are of paramount importance towards to regenerative fuel cells and rechargeable metal-air batteries. Many efforts have been devoted to developing high active ORR and OER bifunctional electrocatalysts to improve the efficiency of devices. However, the possibility of using free solar energy in ORR/OER electrocatalysts to get higher efficiency in the devices has not yet been recognized. Herein, we report a photo-responsive bifunctional ORR/OER electrocatalyst with a built-in p-n heterojunction based on Ni12P5 nanoparticles (NPs) coupled strongly with nitrogen-doped carbon nanotubes (NCNT). The Ni12P5@NCNT hybrid catalyst exhibited unusually high catalytic activities for both ORR (onset potential at 0.90 V vs. RHE) and OER (η = 360 mV @10 mA cm−2) in 0.1 M KOH solution with a ΔE (EOERj=10 - EORR1/2) = 0.82 V, comparable to that of its state-of-the-art counterparts (e.g., Pt for ORR, IrO2 for OER). Upon light irradiation (300 W Xenon lamp equipped with an AM 1.5 G filter, 5 cm to electrode), the ΔE further decreased to 0.80 V. A rechargeable Zn-air battery devised from a Ni12P5@NCNT cathode in 6 M KOH/0.2 M Zn(Ac)2 exhibited a low charge-discharge voltage gap (~0.75 V @ 10 mA cm−2, charge potential = 1.94 V and discharge potential = 1.19 V) and a remarkable cycling stability over 500 cycles, which, upon the light irradiation, showed an even lower charge potential of 1.90 V and higher discharge potential of 1.22 V (i.e., a charge-discharge voltage gap: 0.68 V @ 10 mA cm−2). The irradiation caused also a concomitant increase in the round-trip efficiency from ~61.3% to ~64.2%. To demonstrate the potential applications in portable/wearable electronic devices, we have also developed all solid-state flexible photo-assisted rechargeable Zn-air batteries based on the Ni12P5@NCNT air electrode with high-performance in the both presence and absence of light irradiation. This conceptual demonstration of the first photo-responsive ORR/OER bifunctional catalyst is significant as it reveals a novel catalytic mechanism, from which a class of new bifunctional catalysts with further enhanced photo-responsive performance could be developed, using in other rechargeable metal-air batteries.

    更新日期:2017-11-10
  • Molecular Engineering of Side Chain architecture of Conjugated Polymers Enhances Performance of Photovoltaics by Tuning Ternary Blend Structures
    Nano Energy (IF 12.343) Pub Date : 2017-11-10
    Yu-Che Lin, Hao-Wen Cheng, Yu-Wei Su, Bo-Hsien Lin, Yi-Ju Lu, Chung-Hao Chen, Hsiu-Cheng Chen, Yang Yang, Kung-Hwa Wei

    Several approaches, including the use of small molecule acceptors, novel polymer structures, and tandem cell structures, have been adopted to prepare polymer solar cells displaying high power conversion efficiencies (PCEs). The application of ternary blends as the active layer for polymer solar cells—for which the absorption spectra can be tuned by varying the composition ratios of components—is another facile approach toward optimizing the PCEs of devices. The selection of suitable ternary blends active layer often relies on intuition and remains a formidable challenge. Here, we adopted a systemic approach of not only using the same donor chemical units in the two donor-acceptor (D/A) conjugated polymers with complementary light absorption (energy band gaps) but also varying the side chains architectures as a means of tuning the packing of these semi-planar conjugated polymers, thereby influencing the carrier transport and optimizing the PCE. We employed linear, branch and mixed linear-and-branch side-chain attached benzooxadiazole (BO) as the acceptor (A) units in poly[benzodithiophene-thiophene-benzooxadiazole] (PBDTTBO) conjugated polymers and monitored their interactions with poly[benzodithiophene-fluorothienothiophene] (PTB7-TH), both of which featured the same benzodithiophene (BDTT) donor (D) units. We found that incorporating a minor amount (10%) of D/A conjugated PBDTTBO with such side chains into the PTB7-TH with a fullerene allowed us to tune the packing of the two polymers and, thereby, enhance the PCEs of corresponding ternary blend devices; the PCE of the ternary blend device incorporating PBDTTBO with two branched-side chains, PTB7-TH, and PC71BM increased to 11.4% from 9.0% for the device incorporating only the binary blend of PTB7-TH and PC71BM—a relative increase of more than 25%. This approach of using side chain engineering to tune the structure of a minor conjugated polymer and, thus, influence the packing of another major conjugated polymer that features the same donor chemical units appears to be an effective means of preparing highly efficient polymer cells.

    更新日期:2017-11-10
  • Optimum Cu Nanoparticle Catalysts for CO2 Hydrogenation Towards Methanol
    Nano Energy (IF 12.343) Pub Date : 2017-11-09
    Xue Zhang, Jin-Xun Liu, Bart Zijlstra, Ivo A.W. Filot, Zhiyou Zhou, Shigang Sun, Emiel J.M. Hensen

    Understanding the mechanism of CO2 hydrogenation to methanol is important in the context of renewable energy storage from societal and technological point of view. We use density functional theory calculations to study systematically the effect of the size of Cu clusters on the binding strengths of reactants and reaction intermediates as well as the activation barriers for the elementary reaction steps underlying CO2 hydrogenation. All the elementary reaction barriers exhibit linear scaling relationships with CO and O adsorption energies. Used in microkinetics simulations, we predict that medium-sized Cu19 clusters exhibit the highest CO2 hydrogenation activity which can be ascribed to a moderate CO2 coverage and a low CO2 dissociation barrier. The nanoscale effect is evident from the strong variation of CO and O adsorption energies for clusters with 55 or less Cu atoms. The reactivity of larger clusters and nanoparticles is predicted to depend on surface atoms with low coordination number. Optimum activity is correlated with the bond strength of reaction intermediates determined by the d-band center location of the Cu clusters and the extended surfaces. The presented size-activity relations provide useful insight for the design of better Cu catalysts with maximum mass-specific reactivity for CO2 hydrogenation performance.

    更新日期:2017-11-10
  • Piezoelectric nanofibrous scaffolds as in vivo energy harvesters for modifying fibroblast alignment and proliferation in wound healing
    Nano Energy (IF 12.343) Pub Date : 2017-11-09
    Aochen Wang, Zhuo Liu, Ming Hu, Chenchen Wang, Xiaodi Zhang, Bojing Shi, Yubo Fan, Yonggang Cui, Zhou Li, Kailiang Ren

    Since the last decade, piezoelectric polymer nanofibers have been of great interest in the stimulation of cell growth and proliferation for tissue engineering and wound healing applications. To date, there is no clear understanding of how the piezoelectric properties of piezoelectric materials can be affected by electrospinning parameters and how the piezoelectricity from the electrospun polymer nanofibers produced under optimized electrospinning conditions in vivo would affect cell growth, proliferation and elongation. In this paper, it is shown for the first time how electrospinning parameters, such as solution concentration and collecting distance (from the needle to the rotating mandrel), can affect the piezoelectricity of the poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) nanofibers. Here, the optimized electrospinning conditions for P(VDF-TrFE) nanofibers were achieved and these nanofiber scaffolds (NFSs) were used for implanted energy harvester in SD rats, cell proliferation and cell alignment growth applications. During the process of slightly pulling implanted site of SD rats, the implanted PVDF-TrFE NFSs generated a maximum voltage and current of 6 mV and ~ 6 µA, respectively. With great cytocompatibility and relatively large piezoelectric effect, fibroblast cells grew and aligned perfectly along the electrospinning direction of P(VDF-TrFE) nanofiber direction and cell proliferation rate was enhanced by 1.6 fold. Thus, electrospun P(VDF-TrFE) NFSs show great promise in tissue engineering and wound healing applications.

    更新日期:2017-11-10
  • Polystyrene Stabilized Perovskite Component, Grain and Microstructure for Improved Efficiency and Stability of Planar Solar Cells
    Nano Energy (IF 12.343) Pub Date : 2017-11-09
    Huiyin Zhang, Jiangjian Shi, Lifeng Zhu, Yanhong Luo, Dongmei Li, Huijue Wu, Qingbo Meng

    Polystyrene (PS) is introduced to stabilize the perovskite component, grains and microstructures by forming PS-capped perovskite grains. It is found that the PS coverage has significant advantages in suppressing the component loss and phase separation, obstructing moisture corrosion and promoting crystal self-healing of perovskite films. Besides, with the PS involvement, exceeding 20% efficiency of a planar TiO2 based cell has been achieved by decreasing charge traps and nonradiative recombination.

    更新日期:2017-11-10
  • Reduced Interface Losses in Inverted Perovskite Solar Cells by Using a Simple Dual-Functional Phenanthroline Derivative
    Nano Energy (IF 12.343) Pub Date : 2017-11-08
    Zhao Hu, Jingsheng Miao, Tingting Li, Ming Liu, Imran Murtaza, Hong Meng

    Interface losses at metal/organic interface is a critical issue in organic electronic devices. The interfacial layers play a significant role in enhancing the device performance and the interfacial material design criteria are ongoing challenges to be faced in optimization the device performance. In this work, a simple Phenanthroline derivative Phen-I was synthesized through a quaternization reaction in a high yield without complicated purification process. Besides its good wettability and compatibility of the contact between metal electrode and organic layer, interestingly, Phen-I displays a dual functional property, i.e., it not only lowers the work function of the metallic cathode to increase electron extraction but also can be doped into electron transporting material to enhance the conductivity. The inverted perovskite solar cells (PSCs) with Phen-I as cathode interlayer (CIL) show superior performance both in power conversion efficiency, with a maximum PCE of 18.13%, and devices stability as compared with the control devices. Encouragingly, the best PCE of 19.27% was obtained when the perovskite layer based on FA0.3MA0.7PbI2.7Cl0.3 perovskite system. Meanwhile, the devices with Phen-I as CIL show low J-V hysteresis during the forward and reverse bias sweeping. Subsequent studies demonstrate that the performance of the inverted PSCs also improves to 15.25% using 5% Phen-I:PC61BM as electron transporting layer (ETL). Herein, the interface between the metal electrode and ETL is carefully investigated using a series of electrical and surface potential techniques. These results demonstrate that Phen-I is a dual-functional interlayer material to reduce interface losses, which, highlights the broad promise of this new class of materials for applications in organic electronic devices. Meanwhile, owing to the simple molecular structure, low-cost and solution processible, these intriguing features render Phen-I more suitable for efficient organic electronics in large area printing process.

    更新日期:2017-11-10
  • Spontaneously promoted carrier mobility and strengthened phonon scattering in p-type YbZn2Sb2 via a nanocompositing approach
    Nano Energy (IF 12.343) Pub Date : 2017-11-08
    Xiong Zhang, Bin Zhang, Kun-ling Peng, Xing-chen Shen, Gui-tai Wu, Yan-ci Yan, Shi-jun Luo, Xu Lu, Guo-yu Wang, Hao-shuang Gu, Xiao-yuan Zhou

    Conventional strategies for advancing thermoelectrics via nanocompositing focus on the enhanced phonon scattering induced by nanostructured phase. Here, an effective approach of combining carrier mobility promotion and strengthened phonons scattering to simultaneously improve electrical and thermal transport properties is demonstrated. For the p-type YbZn2Sb2 with InSb nanoinclusions, the Hall mobility is effectively enhanced by InSb in the whole measured temperature, from 56 cm2 V−1s−1 to 162 cm2 V−1s−1 at 300 K. Meanwhile, the carrier density optimization by tuning Yb vacancies leads to 46% improvement in the Seebeck coefficient, overcoming the negative contribution from InSb. Moreover, with the help of interface scattering caused by nanoinclusions, the lattice thermal conductivity is reduced by 45% at 720 K. As a result, the thermoelectric figure of merit ZT is enhanced nearly a factor of three. We believe our method provides a “combined strategy” to enhance thermoelectric performance of YbZn2Sb2 based compounds and should be applicable to other thermoelectric materials.

    更新日期:2017-11-10
  • Si-quantum-dot heterojunction solar cells with 16.2% efficiency achieved by employing doped-graphene transparent conductive electrodes
    Nano Energy (IF 12.343) Pub Date : 2017-11-08
    Jong Min Kim, Sung Kim, Dong Hee Shin, Sang Woo Seo, Ha Seung Lee, Ju Hwan Kim, Chan Wook Jang, Soo Seok Kang, Suk-Ho Choi, Gyea Young Kwak, Kyung Joong Kim, Hanleem Lee, Hyoyoung Lee

    To overcome small- and indirect-bandgap nature of crystalline bulk Si, a lot of efforts have been made to utilize Si quantum dots (SQDs) in optoelectronic devices. By controlling the size of Si quantum dots (SQDs), it is possible to vary the energy bandgap based on quantum confinement effect, which can maximize the power-conversion efficiency (PCE) of solar cells due to the energy harvesting in a broader spectral range. Here, we first employ graphene transparent conductive electrodes (TCEs) for SQDs-based solar cells, showing a maximum PCE of 16.2%, much larger than ever achieved in bulk-Si solar cells with graphene TCEs. In this work, the graphene TCEs are doped with two kinds of materials such as AuCl3 and Ag nanowires for efficient collection of the carriers photo-induced in SQDs. The encapsulation of the doped-graphene TCE with another graphene layer prevents the doping elements from being desorbed or oxidized, thereby making the PCE higher, its doping dependence more evident, and the long-term performance more stable. The observed unique solar cell characteristics prove to be dominated by the trade-off effects between doping-induced variations of diode quality, transmittance/sheet resistance of graphene, energy barrier at the graphene TCE/SQDs interface, and reflectance.

    更新日期:2017-11-10
  • Engineering oxygen vacancy on NiO nanorod arrays for alkaline hydrogen evolution
    Nano Energy (IF 12.343) Pub Date : 2017-11-08
    Tong Zhang, Meng-Ying Wu, Dong-Yang Yan, Jing Mao, Hui Liu, Wen-Bin Hu, Xi-Wen Du, Tao Ling, Shi-Zhang Qiao

    Development of low-cost electrocatalysts toward oxygen evolution (OER) and hydrogen evolution reactions (HER) is crucial for large-scale and clean hydrogen production. Cost-effective transition metal oxide-based catalysts are superbly active for OER; however, their applications in catalyzing HER remain challenging due to unsatisfactory activity and intrinsically poor electronic conductivity. Here, we report the synthesis of NiO nanorods (NRs) with abundant oxygen (O) vacancies via a facile cation exchange strategy. Based on the experimental studies and density functional theory calculations, we demonstrate that the chemical and electronic property of NiO NRs is successfully optimized through O-vacancy engineering; the O-vacancies on the surface of NiO NRs remarkably enhance their electronic conduction and promote HER reaction kinetics simultaneously. The resulting NiO NRs exhibit excellent alkaline HER catalytic activity and durability. Furthermore, these specific designed NiO NRs in situ on carbon fiber paper substrates were directly employed as both HER and OER catalysts for overall water splitting, affording better performance than benchmark Pt and RuO2 catalysts. The successful synthesis of these metal oxides nanomaterials with abundant O-vacancies may pave a new path for rationally fabricating efficient HER/OER bi-functional catalysts.

    更新日期:2017-11-10
  • Holey-engineered electrodes for advanced vanadium flow batteries
    Nano Energy (IF 12.343) Pub Date : 2017-11-07
    Yuchen Liu, Yi Shen, Lihong Yu, Le Liu, Feng Liang, Xinping Qiu, Jingyu Xi

    Vanadium flow battery (VFB) has received tremendous attention because of its advantages such as long lifespan, easy to scale and flexible operation. Fabricating novel electrodes with high power density and wide operating temperature is critical to promote the practical application of VFB for all-climate energy storage. In this work, we describe a well-controlled method to prepare holey-engineered porous graphite felt (PGF) electrodes, in which nanosized pores are evenly distributed on the microscale graphite fibers of the graphite felt. Owing to its excellent electrolyte wettability and greatly enhanced surface area, the as-prepared PGF electrode exhibits high electrochemical activity towards VO2+/VO2+ and V2+/V3+ redox couples. As a result, the VFB single cell assembled with PGF electrodes demonstrates outstanding rate performance under current density up to 300 mA cm−2. The resulting PGF electrode also exhibits superior long-term stability over 3000 charging-discharging cycles at a high current density of 150 mA cm−2, and wide temperature adaptability from −20 °C to 60 °C.

    更新日期:2017-11-10
  • Photoconductive noise microscopy revealing quantitative effect of localized electronic traps on the perovskite-based solar cell performance
    Nano Energy (IF 12.343) Pub Date : 2017-11-07
    Duckhyung Cho, Taehyun Hwang, Dong-guk Cho, Byungwoo Park, Seunghun Hong

    We developed a “photoconductive noise microscopy” method to directly image electronic charge traps distributed on a methylammonium lead iodide perovskite film in a solar cell device. The method enabled quantitative imaging of trap densities along with local photocurrents on the solar cell film. By analyzing the imaging data, we could reveal quantitative correlations between the trap distribution and local photocurrents. The results show that the spatial density of the charge traps has a power-law relationship with the short-circuit currents during a solar cell operation as well as localized photocurrents under a sample bias, indicating that a charge trap distribution in a perovskite film can be a major factor determining the performance of the perovskite-based solar cells.

    更新日期:2017-11-10
  • The enhanced adhesion between overlong TiNxOy/MnO2 nanoarrays and Ti substrate: towards flexible supercapacitors with high energy density and long service life
    Nano Energy (IF 12.343) Pub Date : 2017-11-07
    Jianli Zhang, Yan Li, Yue Zhang, Xingyue Qian, Richao Niu, Rudan Hu, Xufei Zhu, Xin Wang, Junwu Zhu

    Weak adhesion between anodic TiO2 nanotube arrays (TNTAs) and Ti substrate is a nonnegligible obstacle for the preparation of long TNTAs and greatly limits its practical application. The TiNxOy nanoarrays prepared from TNTAs by a high-temperature nitridation process also suffer this defect. In this work, a compact layer (~140 nm in thickness) was introduced into the bottom of TNTAs via an additional anodization, resulting in firm binding between the Ti substrate and TNTAs. Owing to the strong adhesion, overlong TiNxOy nanoarrays up to 29.8 μm without curling can be obtained. Notably, the TiNxOy nanoarrays with average lengths of ~22.8 μm depict an extraordinary specific capacitance of 550.8 mF cm−2 at 0.5 mA cm−2 in 1.0 M H2SO4, which is the highest value of TiNxOy nanoarrays as reported so far. Moreover, TiNxOy/MnO2, TiNxOy/Co-S and TiNxOy/MoS2 nanoarrays were obtained. The loaded thin MnO2 layer presents a superior specific capacitance of 1404.4 F g−1 at 0.5 A g−1 (95.5 mF cm−2 at 0.5 mF cm−2). Flexible symmetric supercapacitor constructed by TiNxOy/MnO2 nanoarrays can offer energy and power densities of 1.24 μWh cm−2 and 9.14 mW cm−2 at 30 mA cm−2, respectively. Remarkably, the assembled TiNxOy/MnO2 flexible supercapacitor achieves excellent cyclic stability with a retention of 93.88% over 10000 cycles. The obtained TiNxOy/Co-S nanoarrays can offer a specific capacitance of 358 mF cm−2 at 0.5 mA cm−2.

    更新日期:2017-11-10
  • High Capacity Binder-free Nanocrystalline GeO2 Inverse Opal Anodes for Li-ion Batteries with Long Cycle Life and Stable Cell Voltage
    Nano Energy (IF 12.343) Pub Date : 2017-11-07
    David McNulty, Hugh Geaney, Darragh Buckley, Colm O'Dwyer

    We demonstrate that crystalline macroporous GeO2 inverse opals exhibit state-of-the-art capacity retention, voltage stability and a very long cycle life when tested as anode materials for Li-ion batteries. The specific capacities and capacity retention obtained from GeO2 IOs are greater than values reported for other GeO2 nanostructures and comparable to pure Ge nanostructures. Unlike pure Ge nanostructures, GeO2 IOs can be prepared in air without complex processing procedures, potentially making them far more attractive from an industrial point of view, in terms of cost and ease of production. Inverse opals are structurally and electrically interconnected, and remove the need for additives and binders. GeO2 IOs show gradual capacity fading over 250 and 1000 cycles, when cycled at specific currents of 150 and 300 mA/g, respectively, while maintaining high capacities and a stable overall cell voltage. The specific capacities after the 500th and 1000th cycles at a specific current of 300 mA/g were ~ 632 and 521 mAh/g respectively, corresponding to a capacity retention in each case of ~ 76% and 63% from the 2nd cycle. Systematic analysis of differential capacity plots obtained from galvanostatic voltage profiles over 1000 cycles offers a detailed insight into the mechanism of charge storage in GeO2 anodes over their long cycle life. Rate capability testing and asymmetric galvanostatic testing demonstrate the ability of GeO2 IO samples to deliver significantly high capacities even at high specific currents (1 A/g).

    更新日期:2017-11-10
  • Mesoporous LaMnO3+δ perovskite from spray−pyrolysis with superior performance for oxygen reduction reaction and Zn−air battery
    Nano Energy (IF 12.343) Pub Date : 2017-11-07
    Long Kuai, Erjie Kan, Wei Cao, Marko Huttula, Sami Ollikkala, Taru Ahopelto, Ari-Pekka Honkanen, Simo Huotari, Wenhai Wang, Baoyou Geng

    Oxygen reduction reaction (ORR) is the key reaction in various electrochemical energy devices. This work reports an inexpensive mesoporous LaMnO3+δ perovskite for ORR with remarkable activity, synthesized by a facile aerosol-spray assisted approach. The mesoporous LaMnO3+δ material shows a factor of 3.1 higher activity (at 0.9 V vs. RHE) than LaMnO3 obtained from co-precipitation method (LMO-CP). Based on results of x-ray absorption near-edge spectroscopy (XANES), x-ray photoelectron spectroscopy (XPS) and Brunauer–Emmett–Teller (BET) analysis, we conclude that the chemical state of surface Mn and the high surface area are the sources to the notably enhanced activity. The study of Zn-air batteries device further confirmed a Pt/C comparable performance in the practical devices with the novel mesoporous LaMnO3+δ catalyst, where the power density at 200 mA/cm2 is only 2.1% lower than in the battery with same-loaded Pt/C catalyst. Therefore, the high mass activity and low-cost of Mn/La may make LaMnO3+δ further approach to the application of electrochemical devices.

    更新日期:2017-11-10
  • Graphdiyne-Modified Cross-Linkable Fullerene as an Efficient Electron-Transporting Layer in Organometal Halide Perovskite Solar Cells
    Nano Energy (IF 12.343) Pub Date : 2017-11-06
    Meng Li, Zhao-Kui Wang, Tin Kang, Yingguo Yang, Xingyu Gao, Chain-Shu Hsu, Yuliang Li, Liang-Sheng Liao

    Interface engineering resulting in good contact, enhanced transport capability, and matched energy levels is indispensable and critical for the development of high-performance planar perovskite solar cells (PSCs). Here, we report an excellent electron-transporting layer (ETL) that can simultaneously enhance the stability and efficiency of n-i-p planar PSCs. Large π-conjugated graphdiyne (GD) was introduced into cross-linkable fullerene [6,6]-phenyl-C61-butyric styryl dendron ester (PCBSD) to improve the film orientation. Raman spectroscopy and 2D grazing incidence X-ray diffraction (GIXRD) measurements revealed that a strong π–π stacking interaction occurred between GD and cross-linkable PCBSD (C-PCBSD), generating a face-on stacked composite film. The orientated C-PCBSD:GD films was favorable for the growth and crystallization of the subsequent perovskite films and provided the merits of superior electron mobility, efficient charge extraction and energy-level tailoring. In addition, the thermally annealed C-PCBSD:GD film provided an adhesive film network with sufficient solvent resistance. Consequently, the perovskite devices delivered a power conversion efficiency of 20.19% with obviously improved cell stability. This indicates a potential application of GD-modified cross-linkable fullerene as an ETL in n-i-p structure PSCs. The finding opens a new route to deposit the fullerene films with ordered orientation by 2D materials with large π-conjugation, and thus to control the subsequent perovskite crystallization.

    更新日期:2017-11-10
  • Interface engineering for high-performance direct methanol fuel cells using multiscale patterned membranes and guided metal cracked layers
    Nano Energy (IF 12.343) Pub Date : 2017-11-06
    Segeun Jang, Sungjun Kim, Sang Moon Kim, Jiwoo Choi, Jehyeon Yeon, Kijoon Bang, Chi-Yeong Ahn, Wonchan Hwang, Min Her, Yong-Hun Cho, Yung-Eun Sung, Mansoo Choi

    Capability to fabricate high-performance membrane electrode assemblies (MEAs) is a key to the commercialization of direct methanol fuel cells (DMFCs). This work reports an interface engineering method to introduce a multiscale patterned membrane and a guided metal cracked layer between the catalyst layer and the membrane by the creep-assisted sequential imprinting and simple stretching technique. The MEA with a multiscale patterned membrane, where the nanopatterns covered the whole surface even on the side surface of microstructures, showed improved performance owing to enhanced mass transport by the thinned electrode, effective utilization of the active sites, and increased Pt utilization. To obtain further performance enhancement, we incorporated a guided gold cracked layer into the MEA with the multiscale patterned membrane. The electrochemically inactive thin gold layer acted as a physical barrier for methanol crossover and the guided cracks provided multiple proton pathways. Our interface engineering utility resulted in an enhancement of the device performance by 42.3% compared with that of the reference.

    更新日期:2017-11-10
  • Architecture and Properties of a Novel Two-Dimensional Carbon Material-Graphtetrayne
    Nano Energy (IF 12.343) Pub Date : 2017-11-04
    Juan Gao, Jiaofu Li, Yanhuan Chen, Zicheng Zuo, Yongjun Li, Huibiao Liu, Yuliang Li
    更新日期:2017-11-05
  • An Innovative Electro-Fenton Degradation System Self-Powered by Triboelectric Nanogenerator Using Biomass-Derived Carbon Materials as Cathode Catalyst
    Nano Energy (IF 12.343) Pub Date : 2017-11-04
    Ye Chen, Miao Wang, Miao Tian, Yingzheng Zhu, Xianjun Wei, Tao Jiang, Shuyan Gao
    更新日期:2017-11-05
  • Rate mechanism of vanadium oxide coated tin dioxide nanowire electrode for lithium ion battery
    Nano Energy (IF 12.343) Pub Date : 2017-11-03
    Lifen Wang, Jian Yan, Zhi Xu, Wenlong Wang, Jianguo Wen, Xuedong Bai
    更新日期:2017-11-05
  • N,B-codoped Defect-rich Graphitic Carbon Nanocages as High Performance Multifunctional Electrocatalysts
    Nano Energy (IF 12.343) Pub Date : 2017-11-03
    Ziyang Lu, Jing Wang, Shifei Huang, Yanglong Hou, Yanguang Li, Yueping Zhao, Shichun Mu, Jiujun Zhang, Yufeng Zhao
    更新日期:2017-11-05
  • Intrinsic rectification in common-gated graphene field-effect transistors
    Nano Energy (IF 12.343) Pub Date : 2017-11-03
    Pierre-Antoine Haddad, Denis Flandre, Jean-Pierre Raskin
    更新日期:2017-11-05
  • Ultrasound-spray Deposition of Multi-Walled Carbon Nanotubes on NiO Nanoparticles-embedded Perovskite Layers for High-performance Carbon-based Perovskite Solar Cells
    Nano Energy (IF 12.343) Pub Date : 2017-11-03
    Yinglong Yang, Haining Chen, Xiaoli Zheng, Xiangyue Meng, Teng Zhang, Chen Hu, Yang Bai, Shuang Xiao, Shihe Yang
    更新日期:2017-11-05
  • 更新日期:2017-11-05
  • Rubidium segregation at random grain boundaries in Cu(In,Ga)Se2 absorbers
    Nano Energy (IF 12.343) Pub Date : 2017-11-03
    Philipp Schöppe, Sven Schönherr, Roland Würz, Wolfgang Wisniewski, Gema Martínez-Criado, Maurizio Ritzer, Konrad Ritter, Carsten Ronning, Claudia S. Schnohr
    更新日期:2017-11-05
  • A Strategy of Selective and Dendrite-Free Lithium Deposition for Lithium Batteries
    Nano Energy (IF 12.343) Pub Date : 2017-11-01
    Jingwei Xiang, Ying Zhao, Lixia Yuan, Chaoji Chen, Yue Shen, Fei Hu, Zhangxiang Hao, Jing Liu, Baixiang Xu, Yunhui Huang
    更新日期:2017-11-01
  • Utilization of self-powered electrochemical systems: metallic nanoparticle synthesis and lactate detection
    Nano Energy (IF 12.343) Pub Date : 2017-10-31
    Chuan-Hua Chen, Pin-Wei Lee, Yu-Hsiang Tsao, Zong-Hong Lin
    更新日期:2017-11-01
  • Analysis on characteristics of contact-area-dependent electric energy induced by ion sorption at solid-liquid interface
    Nano Energy (IF 12.343) Pub Date : 2017-10-31
    Junwoo Park, YoungJun Yang, Soon-Hyung Kwon, Sun Geun Yoon, Youn Sang Kim
    更新日期:2017-11-01
  • Exploring the Mechanism of a Pure and Amorphous Black-Blue TiO2:H Thin Film as a Photoanode in Water Splitting
    Nano Energy (IF 12.343) Pub Date : 2017-10-28
    Junhui Liang, Ning Wang, Qixing Zhang, Bofei Liu, Xiangbin Kong, Changchun Wei, Dekun Zhang, Baojie Yan, Ying Zhao, Xiaodan Zhang
    更新日期:2017-10-28
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  • A Flexible Solar Cell/Supercapacitor Integrated Energy Device
    Nano Energy (IF 12.343) Pub Date : 2017-10-27
    Pei Dong, Marco-Tulio F. Rodrigues, Jing Zhang, Raquel S. Borges, Kaushik Kalaga, Arava L.M. Reddy, Glaura G. Silva, Pulickel M. Ajayan, Jun Lou
    更新日期:2017-10-27
  • Creating 20 nm Thin Patternable Flat Fire
    Nano Energy (IF 12.343) Pub Date : 2017-10-26
    Gang Yang, Zhimao Wu, Wei Wang, Zhaoyun Zhang, Zhiyu Hu
    更新日期:2017-10-27
  • Unraveling pH Dependent Cycling Stability of Ferricyanide/Ferrocyanide in Redox Flow Batteries
    Nano Energy (IF 12.343) Pub Date : 2017-10-26
    Jian Luo, Alyssa Sam, Bo Hu, Camden DeBruler, Xiaoliang Wei, Wei Wang, T. Leo Liu
    更新日期:2017-10-27
  • Single-wall carbon nanotube network enabled ultrahigh sulfur-content electrodes for high-performance lithium-sulfur batteries
    Nano Energy (IF 12.343) Pub Date : 2017-10-26
    Ruopian Fang, Guoxian Li, Shiyong Zhao, Lichang Yin, Kui Du, Pengxiang Hou, Shaogang Wang, Hui-Ming Cheng, Chang Liu, Feng Li
    更新日期:2017-10-27
  • Plasmon Enhanced Quantum Dots Fluorescence and Energy Conversion in Water Splitting Using Shell-Isolated Nanoparticles
    Nano Energy (IF 12.343) Pub Date : 2017-10-26
    Hao Yin, Jun Yi, Zhen-Wei Yang, Zhen-Yang Xu, Shun-Ji Xie, Lei Li, Chao-Yu Li, Juan Xu, Hua Zhang, San-Jun Zhang, Jian-Feng Li, Zhong-Qun Tian
    更新日期:2017-10-27
  • Highly Stretchable Integrated System for Micro-supercapacitor with AC Line Filtering and UV Detector
    Nano Energy (IF 12.343) Pub Date : 2017-10-26
    Chen Chen, Jun Cao, Xinyu Wang, Qiongqiong Lu, Mingming Han, Qingrong Wang, Haitao Dai, Zhiqiang Niu, Jun Chen, Sishen Xie
    更新日期:2017-10-27
  • Nanopillar-array architectured PDMS-based triboelectric nanogenerator integrated with a windmill model for effective wind energy harvesting
    Nano Energy (IF 12.343) Pub Date : 2017-10-25
    Bhaskar Dudem, Nghia Dinh Huynh, Wook Kim, Dong Hyun Kim, Hee Jae Hwang, Dukhyun Choi, Jae Su Yu
    更新日期:2017-10-26
  • Digitalized Self-Powered Strain Gauge for Static and Dynamic Measurement
    Nano Energy (IF 12.343) Pub Date : 2017-10-24
    Zongming Su, Hanxiang Wu, Haotian Chen, Hang Guo, Xiaoliang Cheng, Yu Song, Xuexian Chen, Haixia Zhang
    更新日期:2017-10-25
Some contents have been Reproduced with permission of the American Chemical Society.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
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