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  • Mechanochemistry breaks with expectations
    Nat. Catal. Pub Date : 2018-04-16
    Jörg Weissmüller

    Mechanochemistry breaks with expectations Mechanochemistry breaks with expectations, Published online: 16 April 2018; doi:10.1038/s41929-018-0061-1 Tensile strain of a solid surface can result in either strengthening or weakening of bonds with adsorbates. Adsorption energies of different adsorbate/site combinations may be shifted in different directions — a striking violation of the Brønsted–Evans–Polanyi relation.

    更新日期:2018-04-16
  • Light on the path
    Nat. Catal. Pub Date : 2018-04-16
    Ashwathi Iyer, Elif Ertekin

    Light on the path Light on the path, Published online: 16 April 2018; doi:10.1038/s41929-018-0058-9 Discerning the precise mechanisms of photocatalytic energy conversion has long been a challenge. A computational multiscale approach reveals insights into the reaction pathways and rate-limiting steps of the oxygen evolution reaction, the bottleneck for water splitting on TiO2 surfaces.

    更新日期:2018-04-16
  • Arenes and amines
    Nat. Catal. Pub Date : 2018-04-16
    Enda Bergin

    Arenes and amines Arenes and amines, Published online: 16 April 2018; doi:10.1038/s41929-018-0064-y Arenes and amines

    更新日期:2018-04-16
  • Ensuring reproducibility in computational catalysis
    Nat. Catal. Pub Date : 2018-04-16

    Ensuring reproducibility in computational catalysis Ensuring reproducibility in computational catalysis, Published online: 16 April 2018; doi:10.1038/s41929-018-0068-7 Reproducibility is a cornerstone of science. It is imperative that everyone involved in the generation of scientific knowledge holds themself to the highest standard to ensure reproducibility.

    更新日期:2018-04-16
  • Identifying the key obstacle in photocatalytic oxygen evolution on rutile TiO2
    Nat. Catal. Pub Date : 2018-04-16
    Dong Wang, Tian Sheng, Jianfu Chen, Hai-Feng Wang, P. Hu

    As the bottleneck in photocatalytic water splitting, the oxygen evolution reaction (OER) has drawn huge attention, but its efficiency still falls short of expectations. A widely accepted speculation is that the catalysts’ activity is insufficient (high reaction barriers need to be overcome). Here, we develop a first-principles method to investigate the photocatalytic OER at the water/TiO2(110) interface. A full mechanism uncovering the importance of radicals is determined. Kinetic analysis further enables to quantitatively estimate each possible obstacle in the process. We demonstrate unambiguously that the rate-determining factor of the OER varies with the concentration of surface-reaching photoholes (Ch+). Under experimental conditions, the intrinsic catalytic activity of TiO2(110) does not represent the main obstacle, but all steps involving the photoholes are slow due to their low concentrations. This suggests that the key to enhance the OER efficiency is to increase Ch+ before Ch+ reaches the estimated threshold (Ch+ = ~10−4).

    更新日期:2018-04-16
  • An eye on surface changes
    Nat. Catal. Pub Date : 2018-04-16
    Alexis Grimaud

    An eye on surface changes An eye on surface changes, Published online: 16 April 2018; doi:10.1038/s41929-018-0059-8 For electrocatalysts, the activity and stability is determined by the surface — often just a few atomic layers thick. Now atom probe tomography is used to examine the changing surface of an oxygen evolution catalyst at near-atomic-scale resolution, linking structure to activity and stability.

    更新日期:2018-04-16
  • Catalysing surface film formation
    Nat. Catal. Pub Date : 2018-04-16
    Harry E. Hoster

    Catalysing surface film formation Catalysing surface film formation, Published online: 16 April 2018; doi:10.1038/s41929-018-0060-2 The solid electrolyte interphase that forms on graphite anodes plays a vital role in the performance of lithium-ion batteries. Now research shows that the formation of lithium fluoride deposits — one of the main components of the solid electrolyte interphase — is strongly influenced by the electrocatalytic activity of the anode.

    更新日期:2018-04-16
  • Small temperature changes matter
    Nat. Catal. Pub Date : 2018-04-16
    Jan-Stefan Völler

    Small temperature changes matter Small temperature changes matter, Published online: 16 April 2018; doi:10.1038/s41929-018-0066-9 Small temperature changes matter

    更新日期:2018-04-16
  • Electrocatalytic transformation of HF impurity to H2 and LiF in lithium-ion batteries
    Nat. Catal. Pub Date : 2018-04-09
    Dusan Strmcnik, Ivano E. Castelli, Justin G. Connell, Dominik Haering, Milena Zorko, Pedro Martins, Pietro P. Lopes, Bostjan Genorio, Thomas Østergaard, Hubert A. Gasteiger, Filippo Maglia, Byron K. Antonopoulos, Vojislav R. Stamenkovic, Jan Rossmeisl, Nenad M. Markovic

    The formation of solid electrolyte interphase on graphite anodes plays a key role in the efficiency of Li-ion batteries. However, to date, fundamental understanding of the formation of LiF as one of the main solid electrolyte interphase components in hexafluorophosphate-based electrolytes remains elusive. Here, we present experimental and theoretical evidence that LiF formation is an electrocatalytic process that is controlled by the electrochemical transformation of HF impurity to LiF and H2. Although the kinetics of HF dissociation and the concomitant production of LiF and H2 is dependent on the structure and nature of surface atoms, the underlying electrochemistry is the same. The morphology, and thus the role, of the LiF formed is strongly dependent on the nature of the substrate and HF inventory, leading to either complete or partial passivation of the interface. Our finding is of general importance and may lead to new opportunities for the improvement of existing, and design of new, Li-ion technologies.

    更新日期:2018-04-10
  • Foundations and strategies of the construction of hybrid catalysts for optimized performances
    Nat. Catal. Pub Date : 2018-04-09
    Rong Ye, Jie Zhao, Brent B. Wickemeyer, F. Dean Toste, Gabor A. Somorjai

    Catalysts are generally classified into three categories: homogeneous, heterogeneous and enzyme, each evolved as an independent field. Efforts to bridge these fields are scarce but desirable. In this Perspective, we first describe how numerous classes of reactions can be achieved by all three categories of catalysts. Examples are given based on a selective survey of the literature. Next, a selection of important approaches, the benefits and challenges of constructing heterogeneous–homogeneous, heterogeneous–enzyme and homogeneous–enzyme hybrid catalysts are discussed based on published researches. Hybrid catalysts not only increase the performance, including activity, selectivity, lifetime and recyclability compared to one of the components, but also offer extra functions such as a microenvironment for different reaction pathways, and cascade catalysis for products that are challenging to produce. We expect future tailor-made hybrid catalysts will combine the advantages of the components and be optimized for industrial applications.

    更新日期:2018-04-10
  • Complex dynamics in a two-enzyme reaction network with substrate competition
    Nat. Catal. Pub Date : 2018-04-09
    Yifei Zhang, Stanislav Tsitkov, Henry Hess

    Enzymatic reaction networks capable of generating complex spatiotemporal dynamics are not only the basis of essential biological processes, but also the basic units of synthetic systems with autonomous, adaptive and programmable behaviours. Activation and inhibition have been usually considered as indispensable interactions for the construction of such networks. Here we present an enzymatic reaction network that consists of a flavin adenine dinucleotide-dependent oxidoreductase and a peroxidase that can generate tunable complex dynamics. These include charging/discharging, rectangular and parabolic pulses in a closed system, which are based on delayed and self-adapting substrate competition, rather than on activation or inhibition. Additionally, this system can spontaneously form visible spatiotemporal patterns that arise from reaction-driven Rayleigh–Bénard convection. This work demonstrates that substrate competition could be an alternative path towards constructing biochemical networks with complex dynamics.

    更新日期:2018-04-10
  • Overcoming ammonia synthesis scaling relations with plasma-enabled catalysis
    Nat. Catal. Pub Date : 2018-04-02
    Prateek Mehta, Patrick Barboun, Francisco A. Herrera, Jongsik Kim, Paul Rumbach, David B. Go, Jason C. Hicks, William F. Schneider

    Correlations between the energies of elementary steps limit the rates of thermally catalysed reactions at surfaces. Here, we show how these limitations can be circumvented in ammonia synthesis by coupling catalysts to a non-thermal plasma. We postulate that plasma-induced vibrational excitations in N2 decrease dissociation barriers without influencing subsequent reaction steps. We develop a density-functional-theory-based microkinetic model to incorporate this effect, and parameterize the model using N2 vibrational excitations observed in a dielectric-barrier-discharge plasma. We predict plasma enhancement to be particularly great on metals that bind nitrogen too weakly to be active thermally. Ammonia synthesis rates observed in a dielectric-barrier-discharge plasma reactor are consistent with predicted enhancements and predicted changes in the optimal metal catalyst. The results provide guidance for optimizing catalysts for application with plasmas.

    更新日期:2018-04-03
  • Atomic-scale insights into surface species of electrocatalysts in three dimensions
    Nat. Catal. Pub Date : 2018-03-26
    T. Li, O. Kasian, S. Cherevko, S. Zhang, S. Geiger, C. Scheu, P. Felfer, D. Raabe, B. Gault, K. J. J. Mayrhofer

    The topmost atomic layers of electrocatalysts determine the mechanism and kinetics of reactions in many important industrial processes, such as water splitting, chlor-electrolysis or fuel cells. Optimizing the performance of electrocatalysts requires a detailed understanding of surface-state changes during the catalytic process, ideally at the atomic scale. Here, we use atom probe tomography to reveal the three-dimensional structure of the first few atomic layers of electrochemically grown iridium oxide, an efficient electrocatalyst for the oxygen evolution reaction. We unveil the formation of confined, non-stoichiometric Ir–O species during oxygen evolution. These species gradually transform to IrO2, providing improved stability but also a decrease in activity. Additionally, electrochemical growth of oxide in deuterated solutions allowed us to trace hydroxy-groups and water molecules present in the regions of the oxide layer that are favourable for the oxygen evolution and iridium dissolution reactions. Overall, we demonstrate how tomography with near-atomic resolution advances the understanding of complex relationships between surface structure, surface state and function in electrocatalysis.

    更新日期:2018-03-26
  • Efficient hydrogen peroxide generation using reduced graphene oxide-based oxygen reduction electrocatalysts
    Nat. Catal. Pub Date : 2018-03-26
    Hyo Won Kim, Michael B. Ross, Nikolay Kornienko, Liang Zhang, Jinghua Guo, Peidong Yang, Bryan D. McCloskey

    Electrochemical oxygen reduction has garnered attention as an emerging alternative to the traditional anthraquinone oxidation process to enable the distributed production of hydrogen peroxide. Here, we demonstrate a selective and efficient non-precious electrocatalyst, prepared through an easily scalable mild thermal reduction of graphene oxide, to form hydrogen peroxide from oxygen. During oxygen reduction, certain variants of the mildly reduced graphene oxide electrocatalyst exhibit highly selective and stable peroxide formation activity at low overpotentials (<10 mV) under basic conditions, exceeding the performance of current state-of-the-art alkaline catalysts. Spectroscopic structural characterization and in situ Raman spectroelectrochemistry provide strong evidence that sp2-hybridized carbon near-ring ether defects along sheet edges are the most active sites for peroxide production, providing new insight into the electrocatalytic design of carbon-based materials for effective peroxide production.

    更新日期:2018-03-26
  • The magic of triads
    Nat. Catal. Pub Date : 2018-03-08
    Malte Behrens

    The magic of triads The magic of triads, Published online: 08 March 2018; doi:10.1038/s41929-018-0038-0 Ammonia synthesis is an energy-intensive process due to the high activation barrier for N2 dissociation, which is the rate-determining step on conventional catalysts. Now, a ternary intermetallic catalyst is reported to be capable of catalysing this reaction through an alternative pathway.

    更新日期:2018-03-08
  • Chemoenzymatic asymmetric synthesis of the metallo-β-lactamase inhibitor aspergillomarasmine A and related aminocarboxylic acids
    Nat. Catal. Pub Date : 2018-03-08
    Haigen Fu, Jielin Zhang, Mohammad Saifuddin, Gea Cruiming, Pieter G. Tepper, Gerrit J. Poelarends

    Metal-chelating aminocarboxylic acids are being used in a broad range of domestic products and industrial applications. With the recent identification of the fungal natural product aspergillomarasmine A as a potent and selective inhibitor of metallo-β-lactamases and a promising co-drug candidate to fight antibiotic-resistant bacteria, the academic and industrial interest in metal-chelating chiral aminocarboxylic acids further increased. Here, we report a biocatalytic route for the asymmetric synthesis of aspergillomarasmine A and various related aminocarboxylic acids from retrosynthetically designed substrates. This synthetic route highlights a highly regio- and stereoselective carbon–nitrogen bond-forming step catalysed by ethylenediamine-N,N′-disuccinic acid lyase. The enzyme shows broad substrate promiscuity, accepting a wide variety of amino acids with terminal amino groups for selective addition to fumarate. We also report a two-step chemoenzymatic cascade route for the rapid diversification of enzymatically prepared aminocarboxylic acids by N-alkylation in one pot. This biocatalytic methodology offers a useful alternative route to difficult aminocarboxylic acid products.

    更新日期:2018-03-08
  • Solvents take control
    Nat. Catal. Pub Date : 2018-03-08
    Hu Li, Richard L. Smith Jr

    Solvents take control Solvents take control, Published online: 08 March 2018; doi:10.1038/s41929-018-0040-6 Solvents are used pervasively in catalytic studies to enhance kinetics and selectivities. Now, the analysis of biomass upgrading has been remarkably simplified by elucidating the solvation effects of dehydration for key compounds with solvent-enabled control of reactivity.

    更新日期:2018-03-08
  • Better guidance is cheaper
    Nat. Catal. Pub Date : 2018-03-08
    Jan-Stefan Völler

    Better guidance is cheaper Better guidance is cheaper, Published online: 08 March 2018; doi:10.1038/s41929-018-0048-y Better guidance is cheaper

    更新日期:2018-03-08
  • Catalysis as it goes
    Nat. Catal. Pub Date : 2018-03-08

    Catalysis as it goes Catalysis as it goes, Published online: 08 March 2018; doi:10.1038/s41929-018-0050-4 In situ studies are very important to advance our comprehension of catalytic reactions and are expected to be boosted by the development of more powerful analytical tools.

    更新日期:2018-03-08
  • Pin a methyl on it
    Nat. Catal. Pub Date : 2018-03-08
    Enda Bergin

    Pin a methyl on it Pin a methyl on it, Published online: 08 March 2018; doi:10.1038/s41929-018-0046-0 Pin a methyl on it

    更新日期:2018-03-08
  • The stream of change
    Nat. Catal. Pub Date : 2018-03-08
    Feng Gao, János Szanyi

    The stream of change The stream of change, Published online: 08 March 2018; doi:10.1038/s41929-018-0039-z Fluctuations in the composition of reactant gas mixtures often lead to activity and selectivity variations in automotive catalysts. Now, time-resolved operando spectroscopy sheds light on the transient changes of surface species for a commercially applied catalyst and leads to process optimization.

    更新日期:2018-03-08
  • Enzymes working in reverse
    Nat. Catal. Pub Date : 2018-03-08
    Romas J. Kazlauskas

    Enzymes working in reverse Enzymes working in reverse, Published online: 08 March 2018; doi:10.1038/s41929-018-0041-5 Lyases are enzymes that catalyse the breaking of chemical bonds. Now, reversing this reaction towards carbon–nitrogen bond formation allows for the synthesis of various chiral aminocarboxylic acids such as the potential antibiotic co-drug aspergillomarasmine A.

    更新日期:2018-03-08
  • Author Correction: Opportunities and challenges for combining chemo- and biocatalysis
    Nat. Catal. Pub Date : 2018-03-07
    Florian Rudroff, Marko D. Mihovilovic, Harald Gröger, Radka Snajdrova, Hans Iding, Uwe T. Bornscheuer

    Author Correction: Opportunities and challenges for combining chemo- and biocatalysis Author Correction: Opportunities and challenges for combining chemo- and biocatalysis, Published online: 07 March 2018; doi:10.1038/s41929-018-0042-4 Author Correction: Opportunities and challenges for combining chemo- and biocatalysis

    更新日期:2018-03-08
  • Encapsulating highly catalytically active metal nanoclusters inside porous organic cages
    Nat. Catal. Pub Date : 2018-03-05
    Xinchun Yang, Jian-Ke Sun, Mitsunori Kitta, Huan Pang, Qiang Xu

    The creation of metal nanoclusters with dimensions ranging from subnanometre to ~2 nm for heterogeneous catalysis has received substantial attention. However, synthesizing these structures while retaining surface activity and avoiding aggregation is challenging. Here, we report a reverse double-solvents approach that enables encapsulation of highly catalytically active Pd nanoclusters inside the newly formed discrete organic molecular cage, RCC3. By encapsulating within the open cavities of soluble RCC3 cages, the obtained Pd nanocluster cores are produced with precisely controlled size (~0.72 nm) and show high solubility, excellent dispersibility and accessibility in solution, presenting significantly enhanced catalytic activities towards various liquid-phase catalytic reactions. Moreover, owing to the effective confinement of cage cavities, the as-prepared Pd nanoclusters possess excellent stability and durability. The strategy of encapsulation of metal nanoclusters within soluble porous organic cages is promising for developing stable and active catalysts.

    更新日期:2018-03-06
  • An atomic-scale view of single-site Pt catalysis for low-temperature CO oxidation
    Nat. Catal. Pub Date : 2018-03-05
    Andrew J. Therrien, Alyssa J. R. Hensley, Matthew D. Marcinkowski, Renqin Zhang, Felicia R. Lucci, Benjamin Coughlin, Alex C. Schilling, Jean-Sabin McEwen, E. Charles H. Sykes

    Single-atom catalysts have attracted great attention in recent years due to their high efficiencies and cost savings. However, there is debate concerning the nature of the active site, interaction with the support, and mechanism by which single-atom catalysts operate. Here, using a combined surface science and theory approach, we designed a model system in which we unambiguously show that individual Pt atoms on a well-defined Cu2O film are able to perform CO oxidation at low temperatures. Isotopic labelling studies reveal that oxygen is supplied by the support. Density functional theory rationalizes the reaction mechanism and confirms X-ray photoelectron spectroscopy measurements of the neutral charge state of Pt. Scanning tunnelling microscopy enables visualization of the active site as the reaction progresses, and infrared measurements of the CO stretch frequency are consistent with atomically dispersed Pt atoms. These results serve as a benchmark for characterizing, understanding and designing other single-atom catalysts.

    更新日期:2018-03-06
  • Solvent-enabled control of reactivity for liquid-phase reactions of biomass-derived compounds
    Nat. Catal. Pub Date : 2018-02-26
    Max A. Mellmer, Chotitath Sanpitakseree, Benginur Demir, Peng Bai, Kaiwen Ma, Matthew Neurock, James A. Dumesic

    The use of organic solvents in biomass conversion reactions can lead to high rates and improved selectivities. Here, we elucidate the effects of organic solvent mixtures with water on the kinetics of acid-catalysed dehydration reactions of relevance to biomass conversion. Based on results from reaction kinetics studies, combined with classical and ab initio molecular dynamics simulations, we show that the rates of acid-catalysed reactions in the liquid phase can be enhanced by altering the extents of solvation of the initial and transition states of these catalytic processes. The extent of these effects increases as the number of vicinal hydroxyl or oxygen-containing groups in the reactant increases, moving from an alcohol (butanol), to a diol (1,2-propanediol), to a carbohydrate (fructose). We demonstrate that the understanding of these solvation effects can be employed to optimize the rate and selectivity for production of the biomass platform molecule hydroxymethylfurfural from fructose.

    更新日期:2018-02-27
  • Shining a light on amine synthesis
    Nat. Catal. Pub Date : 2018-02-07
    Joyann S. Barber, Francesca M. Ippoliti, Neil K. Garg

    Shining a light on amine synthesis Shining a light on amine synthesis, Published online: 07 February 2018; doi:10.1038/s41929-018-0026-4 Given the abundance of amines in pharmaceutical substances, new strategies for the formation of C–N bonds are highly sought after. Now, using a dual photoredox–copper catalysis system, a method for amine synthesis has been developed.

    更新日期:2018-02-08
  • Change is in the air
    Nat. Catal. Pub Date : 2018-02-07

    Change is in the air Change is in the air, Published online: 07 February 2018; doi:10.1038/s41929-018-0033-5 Converting carbon dioxide to more useful — and less harmful — chemicals is a key challenge of our time, and one in which catalysis needs to play a key role.

    更新日期:2018-02-08
  • Solid catalysts under the spotlight
    Nat. Catal. Pub Date : 2018-02-07
    Bert M. Weckhuysen

    Solid catalysts under the spotlight Solid catalysts under the spotlight, Published online: 07 February 2018; doi:10.1038/s41929-018-0024-6 Understanding the fundamentals of a catalytic process remains an intellectual challenge. Now, a method has been developed that can discriminate mass transport phenomena from reaction kinetics at the single-molecule and single-particle levels.

    更新日期:2018-02-08
  • Together is better
    Nat. Catal. Pub Date : 2018-02-07
    Davide Esposito

    Together is better Together is better, Published online: 07 February 2018; doi:10.1038/s41929-018-0031-7 Together is better

    更新日期:2018-02-08
  • The basics of volcanoes
    Nat. Catal. Pub Date : 2018-02-07
    Marçal Capdevila-Cortada

    The basics of volcanoes The basics of volcanoes, Published online: 07 February 2018; doi:10.1038/s41929-018-0034-4 The basics of volcanoes

    更新日期:2018-02-08
  • Decarboxylative C(sp3)–N cross-coupling via synergetic photoredox and copper catalysis
    Nat. Catal. Pub Date : 2018-02-07
    Runze Mao, Adrian Frey, Jonathan Balon, Xile Hu

    Amines are a quintessential moiety in bioactive molecules, pharmaceuticals and organic materials. Transition-metal-catalysed C–N coupling of aryl electrophiles has been established as a powerful and reliable method for amine synthesis. However, the analogous C–N coupling of alkyl electrophiles is largely under-developed due to the decomposition of metal alkyl intermediates by β-hydrogen elimination and difficulty in C(sp3)–N reductive elimination. Here, we provide a general strategy for amination of alkyl electrophiles by merging photoredox and copper catalysis. Photoredox catalysis allows the use of alkyl redox-active esters, recently established as a superior class of alkyl electrophiles, whereas copper catalysis enables C(sp3)–N cross-coupling. Decarboxylative amination can be used for the synthesis of a diverse set of alkyl anilines with high chemoselectivity and functional-group compatibility. Rapid functionalization of amino acids, natural products and drugs is demonstrated.

    更新日期:2018-02-08
  • Directing CO2 conversion with copper nanoneedles
    Nat. Catal. Pub Date : 2018-02-07
    Douglas R. Kauffman, Dominic Alfonso

    Directing CO2 conversion with copper nanoneedles Directing CO2 conversion with copper nanoneedles, Published online: 07 February 2018; doi:10.1038/s41929-018-0025-5 Selective, electrochemical transformation of carbon dioxide into industrially relevant C2+ products has remained a challenge. Now, a copper-based ‘nanoneedle’ electrocatalyst has been used to selectively convert carbon dioxide to ethylene at extremely high current density.

    更新日期:2018-02-08
  • An artificial proteasome
    Nat. Catal. Pub Date : 2018-02-07
    Jan-Stefan Völler

    An artificial proteasome An artificial proteasome, Published online: 07 February 2018; doi:10.1038/s41929-018-0035-3 An artificial proteasome

    更新日期:2018-02-08
  • Publisher Correction: Unravelling structure sensitivity in CO2 hydrogenation over nickel
    Nat. Catal. Pub Date : 2018-02-05
    Charlotte Vogt, Esther Groeneveld, Gerda Kamsma, Maarten Nachtegaal, Li Lu, Christopher J. Kiely, Peter H. Berben, Florian Meirer, Bert M. Weckhuysen

    Publisher Correction: Unravelling structure sensitivity in CO2 hydrogenation over nickel Publisher Correction: Unravelling structure sensitivity in CO2 hydrogenation over nickel, Published online: 05 February 2018; doi:10.1038/s41929-018-0036-2 Publisher Correction: Unravelling structure sensitivity in CO2 hydrogenation over nickel

    更新日期:2018-02-06
  • Solvent-determined mechanistic pathways in zeolite-H-BEA-catalysed phenol alkylation
    Nat. Catal. Pub Date : 2018-01-29
    Yuanshuai Liu, Eszter Baráth, Hui Shi, Jianzhi Hu, Donald M. Camaioni, Johannes A. Lercher

    Alkylation of phenolics is of great importance in synthetic chemistry and the valorization of lignocellulosic-biomass-derived streams. Here, we unravel how alkylating reactants and solvents significantly alter the reaction pathways of zeolite-catalysed alkylation of phenol in the liquid phase. The carbenium ion formed from the dehydration of cyclohexanol or from the adsorption and protonation of cyclohexene acts as the electrophile, inducing carbon–carbon bond formation. Cyclohexanol at Brønsted acid sites (BAS) forms hydrogen-bonded monomers and protonated dimers in apolar solvents. The dimer appears to generate a much lower concentration of carbenium ions compared with the monomer. Higher alkylation rates in apolar solvents than in water are caused by the energetically more-favourable carbenium ion formation from either alcohol or olefin on non-hydrated zeolite BAS than on hydronium ions produced by BAS in pores filled with water.

    更新日期:2018-01-30
  • Unravelling structure sensitivity in CO2 hydrogenation over nickel
    Nat. Catal. Pub Date : 2018-01-29
    Charlotte Vogt, Esther Groeneveld, Gerda Kamsma, Maarten Nachtegaal, Li Lu, Christopher J. Kiely, Peter H. Berben, Florian Meirer, Bert M. Weckhuysen

    Continuous efforts in the field of materials science have allowed us to generate smaller and smaller metal nanoparticles, creating new opportunities to understand catalytic properties that depend on the metal particle size. Structure sensitivity is the phenomenon where not all surface atoms in a supported metal catalyst have the same activity. Understanding structure sensitivity can assist in the rational design of catalysts, allowing control over mechanisms, activity and selectivity, and thus even the viability of a catalytic reaction. Here, using a unique set of well-defined silica-supported Ni nanoclusters (1–7 nm) and advanced characterization methods, we prove how structure sensitivity influences the mechanism of catalytic CO2 reduction, the nature of which has been long debated. These findings bring fundamental new understanding of CO2 hydrogenation over Ni and allow us to control both activity and selectivity, which can be a means for CO2 emission abatement through its valorization as a low- or even negative-cost feedstock on a low-cost transition-metal catalyst.

    更新日期:2018-01-30
  • Ternary intermetallic LaCoSi as a catalyst for N2 activation
    Nat. Catal. Pub Date : 2018-01-22
    Yutong Gong, Jiazhen Wu, Masaaki Kitano, Junjie Wang, Tian-Nan Ye, Jiang Li, Yasukazu Kobayashi, Kazuhisa Kishida, Hitoshi Abe, Yasuhiro Niwa, Hongsheng Yang, Tomofumi Tada, Hideo Hosono

    Activating high-energy multiple bonds using earth-abundant metals is one of the most significant challenges in catalysis. Here, we show that LaCoSi—a ternary intermetallic compound—is an efficient and stable catalyst for N2 activation to produce NH3. The ammonia synthesis is significantly promoted by shifting the reaction bottleneck from the sluggish N2 dissociation to NH x formation, which few catalysts have achieved. Theoretical calculations reveal that the negatively charged cobalt mediates electron transfer from lanthanum to the adsorbed N2, which further reduces the activation barrier of N2 dissociation. Most importantly, the specific LaCoSi geometric configuration stabilizes the N2 adsorption with a strong exothermic effect, which dramatically decreases the apparent energy barrier of N2 activation. Consequently, LaCoSi shows a superior activity (1,250 μmol g−1 h−1), with a 60-fold increase over the activity of supported cobalt catalysts under mild reaction conditions (400 °C, 0.1 MPa).

    更新日期:2018-01-23
  • In situ quantitative single-molecule study of dynamic catalytic processes in nanoconfinement
    Nat. Catal. Pub Date : 2018-01-22
    Bin Dong, Yuchen Pei, Fei Zhao, Tian Wei Goh, Zhiyuan Qi, Chaoxian Xiao, Kuangcai Chen, Wenyu Huang, Ning Fang

    Understanding the fundamental catalytic principles when the catalytic centre is confined in nanoscale space that is dimensionally comparable to the reactant molecule is crucial for designing high-performance catalysts. Theoretical studies with simplified model systems and ensemble experimental measurements have shown that chemical reactions in nanoconfined environments are largely different from those in bulk solution. Here, we design a well-defined platform with catalytic centres confined in the end of nanopores with controlled lengths to study the in situ dynamic behaviour of catalytic processes under nanoconfinement at the single-molecule and single-particle level. Variable single molecular mass transport behaviour reveals the heterogeneity of the confined environment in the nanopores. With the capability of decoupling mass transport factors from reaction kinetics in the well-defined platform, we quantitatively uncovered a confinement-induced enhancement in the activity of platinum nanoparticles inside the nanopores. The combination of the unique model catalyst and the single-molecule super-localization imaging technique paves the way to understanding nanoconfinement effects in catalysis.

    更新日期:2018-01-23
  • Control of interfacial acid–metal catalysis with organic monolayers
    Nat. Catal. Pub Date : 2018-01-15
    Jing Zhang, Lucas D. Ellis, Bingwen Wang, Michael J. Dzara, Carsten Sievers, Svitlana Pylypenko, Eranda Nikolla, J. Will Medlin

    Numerous important reactions consisting of combinations of steps (for example, hydrogenation and dehydration) have been found to require bifunctional catalysts with both a late-transition metal component and an acidic component. Here, we develop a method for preparing and controlling bifunctional sites by employing organic acid-functionalized monolayer films tethered to the support as an alternative to traditional ligand-on-metal strategies. This approach was used to create a reactive interface between the phosphonic acid monolayers and metal particles, where active-site properties such as acid strength were manipulated via tuning of the molecular structure of the organic ligands within the monolayer. After surface modification, the resultant catalysts exhibited markedly improved selectivity and activity towards hydrodeoxygenation of aromatic alcohols and phenolics. Moreover, by tuning the ligand of the acidic modifier, the rate of deactivation was significantly reduced.

    更新日期:2018-01-16
  • Metal ion cycling of Cu foil for selective C–C coupling in electrochemical CO2 reduction
    Nat. Catal. Pub Date : 2018-01-15
    Kun Jiang, Robert B. Sandberg, Austin J. Akey, Xinyan Liu, David C. Bell, Jens K. Nørskov, Karen Chan, Haotian Wang

    Electrocatalytic CO2 reduction to higher-value hydrocarbons beyond C1 products is desirable for applications in energy storage, transportation and the chemical industry. Cu catalysts have shown the potential to catalyse C–C coupling for C2+ products, but still suffer from low selectivity in water. Here, we use density functional theory to determine the energetics of the initial C–C coupling steps on different Cu facets in CO2 reduction, and suggest that the Cu(100) and stepped (211) facets favour C2+ product formation over Cu(111). To demonstrate this, we report the tuning of facet exposure on Cu foil through the metal ion battery cycling method. Compared with the polished Cu foil, our 100-cycled Cu nanocube catalyst with exposed (100) facets presents a sixfold improvement in C2+ to C1 product ratio, with a highest C2+ Faradaic efficiency of over 60% and H2 below 20%, and a corresponding C2+ current of more than 40 mA cm–2.

    更新日期:2018-01-16
  • Catalyst electro-redeposition controls morphology and oxidation state for selective carbon dioxide reduction
    Nat. Catal. Pub Date : 2018-01-15
    Phil De Luna, Rafael Quintero-Bermudez, Cao-Thang Dinh, Michael B. Ross, Oleksandr S. Bushuyev, Petar Todorović, Tom Regier, Shana O. Kelley, Peidong Yang, Edward H. Sargent

    The reduction of carbon dioxide to renewable fuels and feedstocks offers opportunities for large-scale, long-term energy storage. The synthesis of efficient CO2 reduction electrocatalysts with high C2:C1 selectivity remains a field of intense interest. Here we present electro-redeposition, the dissolution and redeposition of copper from a sol–gel, to enhance copper catalysts in terms of their morphology, oxidation state and consequent performance. We utilized in situ soft X-ray absorption spectroscopy to track the oxidation state of copper under CO2 reduction conditions with time resolution. The sol–gel material slows the electrochemical reduction of copper, enabling control over nanoscale morphology and the stabilization of Cu+ at negative potentials. CO2 reduction experiments, in situ X-ray spectroscopy and density functional theory simulations revealed the beneficial interplay between sharp morphologies and Cu+ oxidation state. The catalyst exhibits a partial ethylene current density of 160 mA cm–2 (−1.0 V versus reversible hydrogen electrode) and an ethylene/methane ratio of 200.

    更新日期:2018-01-16
  • High-efficiency oxygen reduction to hydrogen peroxide catalysed by oxidized carbon materials
    Nat. Catal. Pub Date : 2018-01-15
    Zhiyi Lu, Guangxu Chen, Samira Siahrostami, Zhihua Chen, Kai Liu, Jin Xie, Lei Liao, Tong Wu, Dingchang Lin, Yayuan Liu, Thomas F. Jaramillo, Jens K. Nørskov, Yi Cui

    Hydrogen peroxide (H2O2) is a valuable chemical with a wide range of applications, but the current industrial synthesis of H2O2 involves an energy-intensive anthraquinone process. The electrochemical synthesis of H2O2 from oxygen reduction offers an alternative route for on-site applications; the efficiency of this process depends greatly on identifying cost-effective catalysts with high activity and selectivity. Here, we demonstrate a facile and general approach to catalyst development via the surface oxidation of abundant carbon materials to significantly enhance both the activity and selectivity (~90%) for H2O2 production by electrochemical oxygen reduction. We find that both the activity and selectivity are positively correlated with the oxygen content of the catalysts. The density functional theory calculations demonstrate that the carbon atoms adjacent to several oxygen functional groups (–COOH and C–O–C) are the active sites for oxygen reduction reaction via the two-electron pathway, which are further supported by a series of control experiments.

    更新日期:2018-01-16
  • General synthesis and definitive structural identification of MN4C4 single-atom catalysts with tunable electrocatalytic activities
    Nat. Catal. Pub Date : 2018-01-08
    Huilong Fei, Juncai Dong, Yexin Feng, Christopher S. Allen, Chengzhang Wan, Boris Volosskiy, Mufan Li, Zipeng Zhao, Yiliu Wang, Hongtao Sun, Pengfei An, Wenxing Chen, Zhiying Guo, Chain Lee, Dongliang Chen, Imran Shakir, Mingjie Liu, Tiandou Hu, Yadong Li, Angus I. Kirkland, Xiangfeng Duan, Yu Huang

    Single-atom catalysts (SACs) have recently attracted broad research interest as they combine the merits of both homogeneous and heterogeneous catalysts. Rational design and synthesis of SACs are of immense significance but have so far been plagued by the lack of a definitive correlation between structure and catalytic properties. Here, we report a general approach to a series of monodispersed atomic transition metals (for example, Fe, Co, Ni) embedded in nitrogen-doped graphene with a common MN4C4 moiety, identified by systematic X-ray absorption fine structure analyses and direct transmission electron microscopy imaging. The unambiguous structure determination allows density functional theoretical prediction of MN4C4 moieties as efficient oxygen evolution catalysts with activities following the trend Ni > Co > Fe, which is confirmed by electrochemical measurements. Determination of atomistic structure and its correlation with catalytic properties represents a critical step towards the rational design and synthesis of precious or nonprecious SACs with exceptional atom utilization efficiency and catalytic activities.

    更新日期:2018-01-16
  • Opportunities and challenges for combining chemo- and biocatalysis
    Nat. Catal. Pub Date : 2018-01-08
    Florian Rudroff, Marko D. Mihovilovic, Harald Gröger, Radka Snajdrova, Hans Iding, Uwe T. Bornscheuer

    The past decade has seen a substantial increase in successful examples of the combination of chemo- and biocatalysis for multistep syntheses. This is driven by obvious advantages such as higher yields, decreased costs, environmental benefits and high selectivity. On the downside, efforts must be undertaken to combine the divergent reaction conditions, reagent tolerance and solvent systems of these ‘different worlds of catalysis’. Owing to progress in enzyme discovery and engineering, as well as in the development of milder and more compatible conditions for operating with various chemocatalysts, many historical limitations can already be overcome. This Review highlights the opportunities available in the chemical space of combined syntheses using prominent examples, but also discusses the current challenges and emerging solutions, keeping in mind the fast progress in transition metal-, organo-, photo-, electro-, hetero- and biocatalysis.

    更新日期:2018-01-16
  • Imine hydrogenation with simple alkaline earth metal catalysts
    Nat. Catal. Pub Date : 2018-01-08
    Heiko Bauer, Mercedes Alonso, Christian Färber, Holger Elsen, Jürgen Pahl, Andrea Causero, Gerd Ballmann, Frank De Proft, Sjoerd Harder

    Hydrogenation of unsaturated bonds is dominated by transition metal catalysis. Compared with transition metals, the use of other metals is less explored, especially so for the s-block elements despite their ready availability and low cost. Here, we show that group 2 metal amides (M[N(SiMe3)2]2, M = Mg, Ca, Sr, Ba) unexpectedly catalyse the hydrogenation of aldimines with H2 at 80 °C and a remarkably low H2 pressure of 1–6 bar. Conversion rates increase with metal size: Mg < Ca < Sr < Ba (for Ba, quantitative conversion is reached within 15 min). The key to this catalysis is the unanticipated formation of metal hydride species by deprotonation of H2 (pKa ≈ 49) with a weak base M[N(SiMe3)2]2 (HN(SiMe3)2: pKa ≈ 25.8). Density functional theory calculations suggest that the most favourable pathway indeed involves metal hydride intermediates. The efficient alkaline earth metal-catalysed hydrogenation of imines with molecular hydrogen at remarkably low pressure provides an attractive alternative to transition metal catalysis.

    更新日期:2018-01-16
  • Catalysing water oxidation using nature’s metal
    Nat. Catal. Pub Date : 2018-01-08
    Gary W. Brudvig

    Catalysing water oxidation using nature’s metal Catalysing water oxidation using nature’s metal, Published online: 08 January 2018; doi:10.1038/s41929-017-0013-1 In nature, a manganese catalyst is used for photosynthetic water oxidation, but efforts to develop artificial manganese-based counterparts have been hampered by the lability of manganese complexes. By using a bulky and hydrophilic ligand, a water-soluble Mn12 complex is found to be a stable and efficient water oxidation electrocatalyst.

    更新日期:2018-01-16
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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