Search

The controllable anchoring of multiple metal single‐atoms (SAs) into a single support exhibits scientific and technological opportunities, while marrying the concentration‐complex multimetallic SAs and high‐entropy SAs (HESAs) into one SAC system remains a substantial challenge. Here, we present a substrate‐mediated SAs formation strategy to successfully fabricate a library of multimetallic SAs and HESAs on MoS2 and MoSe2 supports, which can precisely control the doping location of SAs. Specially, the contents of SAs can continuously increase until the accessible Mo atoms on TMDs carriers are completely replaced by SAs, thus allowing the of much higher metal contents. In‐depth mechanistic study shows that the well‐controlled synthesis of multimetallic SAs and HESAs is realized by controlling the reversible redox reaction occurred on the TMDs/TM ion interface. As a proof‐of‐concept application, a variety of SAs‐TMDs were applied to hydrogen evolution reaction. The optimized HESAs‐TMDs (Pt,Ru,Rh,Pd,Re‐MoSe2) delivers a much higher activity and durability than state of‐the‐art Pt. Thus, our work will broaden the family of single‐atom catalysts and provide a new guideline for the rational design of high‐performance single‐atom catalysts. [ABSTRACT FROM AUTHOR]

Single‐atom catalysts (SACs), as a novel emerging category in heterogeneous catalysis, have exhibited superb activity and selectivity within the scope of many catalytic reactions, originating from their nature of atomic dispersion. However, they are not appropriate for more complicated reactions that benefit from multi‐metal promotion, such as the carbon dioxide reduction reaction (CO2RR). Atomic pair catalysts can provide a synergistic effect to break the intrinsic activity limit. Herein, inspired by theoretical prediction, a hetero‐paired atomic‐site catalyst (Ni/Fe−N/O−C) was developed for CO2RR. Typically, the trace‐amount‐loaded double‐atom‐site catalysts exhibited outstanding turnover frequencies (≈460 s−1) surpassing reported ones by far. Interestingly, the loaded metal contents of the three M−N/O−C samples were extremely low, and Ni/Fe−N/O−C exhibited greatly improved durability compared with pure Ni−N/O−C or Fe−N/O−C and excellent CO selectivity above 80 % within a broad potential window of −1.4 to −1.7 V (vs. saturated calomel electrode, 99.8 % at −1.5 V). The superb performance of diatomic‐site catalysts was attributed to the adjusted local environment and electron structure of the active center, which could decrease the reaction barrier of *COOH formation. This work presents new insights into manipulating electrocatalytic performance for the development of more sophisticated active sites. [ABSTRACT FROM AUTHOR]

Photocatalytic and electrocatalytic N2 reduction reactions (N2RR) for NH3 synthesis from abundant N2, H2O, solar energy, and renewable electricity is very attractive. 2D catalysts, including photocatalysts (TiO2, Bismuth‐based materials, layered double hydroxides (LDHs), carbon nitride, Fe@Graphene, MoS2 et al.) and electrocatalysts (metal, graphene, carbon, boron nitride (BN), boron carbide (B4C), black phosphorus (BP), boron, transition‐metal oxide/sulfide/nitride/phosphide), have emerged as promising candidates for N2RR due to their unique physical, chemical and electronic properties. Compared with their bulk counterparts, 2D catalysts usually possess the shortened carrier diffusion pathways, higher specific surface areas and conductivity, more vacancy‐type defects as well as exposed edge sites, which is beneficial to the separation of photogenerated carriers, and the adsorption and activation of N2 molecules. This review highlights the recent progress and developments in 2D catalysts for photocatalytic and electrocatalytic N2RR for the first time. First, the prospects for photocatalytic and electrocatalytic N2RR for NH3 synthesis, and the advantages of 2D catalysts are briefly introduced. Second, the application of 2D catalysts for N2 photoreduction and electroreduction is systematically summarized. Finally, the major challenges and future outlook of this burgeoning area are provided. [ABSTRACT FROM AUTHOR]

Electrochemical reduction of CO2 may provide a promising method to mitigate the concentration of CO2 in the atmosphere, and simultaneously convert this greenhouse gas into value‐added fuels or chemicals. However, electrocatalysts for CO2 reduction are mostly powder based; therefore, polymer binders are always employed to make these catalysts useful as working electrodes. As a consequence, plenty of active sites are embedded inside without catalytic performance, causing a relatively low efficiency. On the contrary, self‐supported electrocatalysts do not involve the typical powdering and drop‐coating procedure with the aid of polymer binders or additives, avoiding the weak contact between active materials and current collector. Moreover, the superior self‐supported structure can also provide an accelerated electron transfer, guarantee ample electrolyte access to the active sites, offer large electrochemical surface areas, and increase CO2 adsorption capacity around the active sites, finally leading to the excellent efficiency and long‐term stability in CO2 reduction. In this manuscript, recent advances regarding CO2 reduction by self‐supported electrocatalysts are comprehensively reviewed, including the synthesis methods, chemical compositions, nanostructures, and catalytic efficiencies. Furthermore, the existing challenges and perspectives on the research and development of self‐supported electrocatalysts for CO2 reduction are discussed. [ABSTRACT FROM AUTHOR]

Copyright of Angewandte Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Keywords: 2D catalysts; electrocatalysis; N2 reduction reaction; NH3; photocatalysis EN 2D catalysts electrocatalysis N2 reduction reaction NH3 photocatalysis 1 1 1 03/22/21 20210318 NES 210318 The Cowherd and Weaving Maid is a famous folk love story in ancient China. 2D Electrocatalysts: Recent Progress in 2D Catalysts for Photocatalytic and Electrocatalytic Artificial Nitrogen Reduction to Ammonia (Adv. 2D catalysts, electrocatalysis, N2 reduction reaction, NH3, photocatalysis. [Extracted from the article]

A facile route to scalable production of N and S co‐doped, hierarchically porous carbon nanofiber (NSHCF) membranes (ca. 400 cm2 membrane in a single process) is reported. As‐synthesized NSHCF membranes are flexible and free‐standing, allowing their direct use as cathodes for efficient electrochemical CO2 reduction reaction (CO2RR). Notably, CO with 94 % Faradaic efficiency and −103 mA cm−2 current density are readily achieved with only about 1.2 mg catalyst loading, which are among the best results ever obtained by metal‐free CO2RR catalysts. On the basis of control experiments and DFT calculations, such outstanding CO Faradaic efficiency can be attributed to the co‐doped pyridinic N and carbon‐bonded S atoms, which effectively decrease the Gibbs free energy of key *COOH intermediate. Furthermore, hierarchically porous structures of NSHCF membranes impart a much higher density of accessible active sites for CO2RR, leading to the ultra‐high current density. [ABSTRACT FROM AUTHOR]

Rational designing of efficient bifunctional oxygen electrocatalysts is significantly important but rather challenging for rechargeable zinc-air batteries. Herein, a novel high-performance bifunctional oxygen electrocatalyst for rechargeable zinc–air batteries are constructed based on bimetal Mn@Co-N-C encapsulated in in situ grown N,S-doped graphitic carbon framework with within a porous three-dimensional (3D) structure. The final catalyst shows a high half-wave potential of 0.89 V for oxygen reduction reaction, and a low operating overpotential of 0.38 V to achieve a 10 mA cm−2 current density for oxygen evolution reaction. The physical characterizations reveal that a strong synergetic coupling between bimetal Mn@Co-N-C and S dopant can effectively increase the active sites, meanwhile achieve a rational manipulation of the active site configuration toward a favorable electronic structure. Impressively, the assembled zinc–air batteries using liquid electrolytes and the all-solid-state batteries with this catalyst exhibit excellent charging–discharging performance, long lifetime, and high flexibility. [Display omitted] • The second metal source is Mn, which utilizes a controlled self-assembly method to orient on N, S-doped carbon-based materials generated from MOFs. • The synthesized Mn@Co-NS catalyst exhibits excellent bifunctional electrocatalytic activity. • The reasons for the superior performance of Mn@CO-NS catalysts are revealed. • Mn@Co-NS has good performance and long-term stability in the field of zinc-air batteries. • It provides direction guidance for the qualitative landing of various metals on carbon substrates, bringing the application of zinc-air batteries to a new level. [ABSTRACT FROM AUTHOR]

Single-atom catalysts (SAC) stabilized by nitrogen in carbon support are promising candidates for oxygen reduction reaction (ORR). However, conventional preparation methods usually lead to encapsulation of metallic centers in matrix and thus the utilization efficiency (UE) is underexploited. Herein, we report a novel strategy to prepare an Fe-SAC with all Fe atoms anchored on the surface of carbon nanospheres, which exhibited an extraordinary UE of 80% for ORR. This efficiency was achieved by coating polydopamine spheres with silica, followed by the pyrolysis of their blend with FeCl 3. During thermal treatment, Fe migrates across the silica shell by atomic exchange with silicon, which inhibits the aggregation of Fe and allows Fe atoms to anchor on the surface. As such, it showed excellent ORR activity at a low Fe content. Zn-air batteries assembled using this catalyst showed a peak power density of 113 mW cm−2 and specific capacity of 710 mAh g Zn −1. [Display omitted] • A single atomic Fe catalyst anchored on carbon nanosphere was prepared. • All Fe species were single-atomic and fully exposed due to restriction of silica. • The method can be extended to prepare other single-atom catalysts. • The catalyst exhibited excellent catalytic performance at a low loading of Fe. [ABSTRACT FROM AUTHOR]

The precise design and controllable manufacture of electrocatalysts for efficient oxygen reactions (OER and ORR) based on the abundant elements of the earth are urgently required but challenging task. In this study, a CoS 2 /Cu 2 S heterostructured composite (CoS 2 /Cu 2 S-NF) supported by the porous carbon nanofibers is synthesized as a high-efficiency oxygen reaction electrocatalyst. As indicated from in-situ characterization methods (infrared, Raman and XRD) integrated with the density functional theory results, the heterostructures exhibited by CoS 2 and Cu 2 S could be regulated. The results show that the electron transfer/interaction between CoS 2 and Cu 2 S in the heterojunction were regulated, as well as the electronic structures of Co and Cu sites. As impacted by the structural engineering and the electronic modulation, the activity was enhanced, and the performance of electrocatalytic oxygen reactions was improved, which exhibited the lowest potential difference for (ΔE = 0.73 V) compared with commercial electrocatalysts. The liquid ZAB in accordance with on CoS 2 /Cu 2 S-NF exhibited a stable charge and discharge capacity up to 590 h and a great power density reaching 260.60 mW cm−2. Moreover, the flexible solid-state ZAB based on CoS 2 /Cu 2 S-NF exhibited a great competitive power density (92.06 mW cm−2), robust flexibility and an obvious integration. As compared with single metal sulfide-NF, the Density functional theory calculations (DFT) highlight the adsorption on CoS 2 /Cu 2 S-NF side surface in the heterojunction, which more specifically demonstrates the synergistic effect in the junction. This work presents a direction for designing heterostructured junctions as electrocatalyst and moreover its great application potential in rechargeable metal-solid batteries. [Display omitted] • Heterostructure CoS 2 /Cu 2 S-NF shows outstanding catalysis activity for OER and ORR. • The electrocatalytic mechanism is revealed by DFT calculation and in-situ techniques. • CoS 2 /Cu 2 S-NF employing Zn-air battery displays excellent performance. • The flexible Zn-air battery was fabricated by using CoS 2 /Cu 2 S-NF. [ABSTRACT FROM AUTHOR]