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[Display omitted] • Hollow CoVO x /Ag heterojunction was synthesized for OER. • The interaction of CoVO x and Ag nanoparticles regulated the electronic structure. • The extrinsic catalytic activity of CoVO x /Ag is enhanced due to the hollow structure. • The OER overpotential for CoVO x /Ag-5 at 10 mA cm−2 is only 247 mV. • The catalyst can enable full water splitting with 100% Faraday efficiency. Developing high-active and inexpensive electrocatalysts for oxygen evolution reaction (OER) is very important in the field of water splitting. The catalytic performance of electrocatalysts can be significantly improved by optimizing the electronic structure and designing suitable nanostructure. In this work, we represent the synthesis of hollow CoVO x /Ag-5 for OER. Due to the interaction of CoVO x and Ag nanoparticles, the electronic structure is optimized to improve the intrinsic catalytic activity. Additionally, the extrinsic catalytic activity of CoVO x /Ag is enhanced by the abundant active sites from the hollow structure. As a result, the CoVO x /Ag-5 demonstrates significantly enhanced OER catalytic activity with a low overpotential of 247 mV at 10 mA cm−2. In addition, it also exhibits excellent durability, without obvious attenuation in performance after continuous operation for 60 h. Furthermore, the catalyst can enable full water splitting with appropriate 100 % Faraday efficiency, demonstrating its practical application. [ABSTRACT FROM AUTHOR]

Considering the much lower price of Ru compared with Pt, Ru-based catalysts are potential alternatives for the hydrogen evolution reaction, and developing a low-cost carrier and reducing the size of Ru nanoparticles are useful strategies to promote the usage of Ru-based catalysts. In this work, we report a facile method to prepare 3D hierarchical carbon with highly dispersed Ru nanoparticles using zinc citrate as the carbon precursor. Combined with the fast mass transport provided by the 3D hierarchical carbon and the high activity of ultrafine Ru nanoparticles, the prepared Ru–C catalyst exhibits remarkable hydrogen evolution reaction (HER) activity over a wide pH range, with overpotentials of 33, 50, and 90 mV in 0.5 M H2SO4, 1 M KOH, and 1 M phosphate-buffered saline, respectively, comparable to commercial Pt/C and surpassing many Ru-based electrocatalysts. This work provides an alternative route for preparing highly efficient HER catalysts based on the application of low-cost organic zinc salts as the carbon precursor, which is very attractive for large-scale applications. [ABSTRACT FROM AUTHOR]

A novel CoMoO 4 -RuO 2 heterogeneous catalyst with flower-liked morphology was developed as a highly efficient bifunctional oxygen electrocatalyst for Zn-air battery. [Display omitted] Constructing heterogeneous catalysts can significantly boost the electrocatalytic activity due to the improved intrinsic catalytic activity induced by tailored electronic structure and optimized chemisorption to the reaction intermediates. RuO 2 based electrocatalysts are especially attractive due to the high catalytic activity of RuO 2. To reduce the usage of noble metal and improve the catalytic activity of catalyst, CoMoO 4 -RuO 2 micro-flower was synthesized using a facile hydrothermal-calcination method in this work. CoMoO 4 -RuO 2 exhibits a low overpotential of 177 mV at 10 mA cm−2 for oxygen evolution reaction (OER) and a high half-wave potential of 0.858 V for oxygen reduction reaction (ORR). Moreover, the Zn-air battery assembled using CoMoO 4 -RuO 2 exhibit shows a high maximum discharge power density of 149 mW cm−2 and a large open circuit voltage of 1.38 V. The good performance can be attributed to the incorporation of RuO 2 , which not only induces extra catalytic active sites, but also forms heterojunction with CoMoO 4 to optimize the electronic structure of CoMoO 4 -RuO 2 , thereby achieving a better equilibrium of absorption and desorption of intermediates. The work provides insights into designing RuO 2 based electrocatalysts for advanced electrocatalysis. [ABSTRACT FROM AUTHOR]

Single-atom catalysts with precise structure and tunable coordination nature provide opportunities for developing novel catalytic centers and understanding reaction mechanisms. Herein, hollow Co9S8 polyhedrons with lattice-confined Ru single atoms (Ru-Co9S8) are fabricated. Aberration-corrected scanning transmission electron microscopy and X-ray absorption spectroscopy verify the isolated Ru atoms are confined in Co9S8 to form Co-S-Ru catalytic centers. Theoretical calculations indicate that the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) energy barriers are extensively reduced, and the d-band center of Co9S8 downshifts from the Fermi level, therefore boosting the desorption of O-containing intermediates. Consequently, the Ru-Co9S8 exhibits an ultralow overpotential of 163 mV at 10 mA·cm−2 for OER and could catalyze a rechargeable Zn-air battery with a high-power density of 92.0 mW·cm−2. This work provides a promising approach for designing novel bifunctional catalytic active centers for energy conversion. [ABSTRACT FROM AUTHOR]

Development and utilization of hydrogen energy is an effective way to achieve carbon neutrality, only hydrogen production through electrolytic water splitting meets the goal of zero carbon emission. To facilitate the large‐scale commercialization of water splitting devices, the development of highly efficient and low‐cost catalysts to reduce the energy consumption is essential. MoS2 has been regarded as a promising electrocatalyst to replace platinum in hydrogen evolution reaction due to its low price and unique 2D layered structure. However, the poor conductivity and inert basal planes of MoS2 limited its wide‐spread application. Recently, researches have demonstrated that the conductivity and active sites of MoS2 can be improved by heteroatoms doping or constructing of heterogeneous structures. In this review, the recent progress of Mo‐based catalysts are summarized centered on MoS2 based on interface engineering and anion engineering, including MoS2–MoO2, MoS2–Mo2C, MoS2–MoNx, MoS2–MoP, and MoS2–MoSe2. The preparation method, structure, and performance of the catalysts are introduced and the possible mechanism behind the improved catalytic activity are revealed to give readers an overall comprehension on the progress of the Mo‐based electrocatalysts for hydrogen evolution reaction. In addition, an outlook on future opportunities and development directions of Mo‐based catalysts are proposed to facilitate the development of Mo‐based catalysts for hydrogen production. [ABSTRACT FROM AUTHOR]

Hydrogen serves as a potent and environment friendly energy source, and developing high performance hydrogen evolution reaction (HER) electrocatalysts is crucial for water splitting. In this work, Pt nanoparticles incorporated NiO nanoflower (Pt-NiO) is synthesized using an ethylene glycol reduction method. The incorporation of Pt not only introduces extra high active sites, but also induces strong interaction between NiO and Pt. Meanwhile, the NiO nanoflower support enables the dispersion of Pt and ensure high electrochemically surface area as well as fast mass transport, which greatly improves catalytic activity of Pt-NiO. Pt-NiO-3 only requires a small overpotential of 26 mV to reach 10 mA cm−2 and the Tafel slope is only 19.49 mV dec−1. In addition, the mass activity can achieve 2000 mA mg Pt −1 at an overpotential of 63 mV. Moreover, obvious bubbles can be observed in the assembled H-type for overall water splitting, and the Faraday efficiency is close to 100 %, highlighting the superiority of Pt-NiO-3. This work provides insights for designing high effective electrocatalysts for HER. [Display omitted] • Pt nanoparticles incorporated NiO nanoflower is synthesized using an ethylene glycol reduction method. • The incorporation of Pt induces strong interaction between NiO and Pt. • NiO nanoflower enables high electrochemically surface area and fast mass transport. • Pt-NiO-3 only requires a small overpotential of 26 mV to reach 10 mA cm−2. • The mass activity of Pt-NiO-3 is 2000 mA mg Pt −1 at an overpotential of 63 mV. [ABSTRACT FROM AUTHOR]

Single‐atom catalysts (SACs) have attracted increasing research interests owing to their unique electronic structures, quantum size effects and maximum utilization rate of atoms. Metal organic frameworks (MOFs) are good candidates to prepare SACs owing to the atomically dispersed metal nodes in MOFs and abundant N and C species to stabilize the single atoms. In addition, the distance of adjacent metal atoms can be turned by adjusting the size of ligands and adding volatile metal centers to promote the formation of isolated metal atoms. Moreover, the diverse metal centers in MOFs can promote the preparation of dual‐atom catalysts (DACs) to improve the metal loading and optimize the electronic structures of the catalysts. The applications of MOFs derived SACs and DACs for electrocatalysis, including oxygen reduction reaction, oxygen evolution reaction, hydrogen evolution reaction, carbon dioxide reduction reaction and nitrogen reduction reaction are systematically summarized in this Review. The corresponding synthesis strategies, atomic structures and electrocatalytic performances of the catalysts are discussed to provide a deep understanding of MOFs‐based atomic electrocatalysts. The catalytic mechanisms of the catalysts are presented, and the crucial challenges and perspectives are proposed to promote further design and applications of atomic electrocatalysts. [ABSTRACT FROM AUTHOR]

Oxygen reduction reaction (ORR) catalysts with hierarchical pore structures, high specific surface area and multiple heteroatoms doping is very attractive due to the rapid mass transport and abundant active sites. In this work, we reported a facile confined strategy to prepare N, P co‐doped hierarchical porous carbon (NPHC) and investigated their catalytic performance for ORR. The strategy greatly simplifies the synthesis procedure of 3D hierarchical carbon templated by SiO2, which can utilize small organic molecules as carbon sources and avoids the pre‐polymerization and post‐washing process. Moreover, this strategy can be readily extended to synthesis other carbons by simply changing the carbon sources and heteroatom sources, or to synthesize metal compounds/carbon composites by adding metal sources during the synthesis process for energy conversion and storage. [ABSTRACT FROM AUTHOR]

Transition-metal chalcogenides especially MoS 2 are promising candidates as highly efficient electrocatalyst for hydrogen evolution reaction (HER). Nevertheless, the low conductivity and inert basal planes of MoS 2 limit its performance. In addition, the oxygen evolution reaction (OER) catalytic activity of MoS 2 is low. In this work, we report the synthesis of self-supported 1 T-MoS 2 /Co 3 S 4 /Ni 3 S 2 nanoarrays for overall water splitting. 1 T-MoS 2 can enhance electron transfer during the reaction process. Meanwhile, abundant interfaces and defects exist in the heterogeneous catalysts, which can bring more active sites and result in strong interaction among the different components. As a result, the 1 T-MoS 2 /Co 3 S 4 /Ni 3 S 2 nanoarray exhibits low overpotentials of 50 and 240 mV is achieved at 10 mA cm−2 for HER and OER with very high stability. In addition, it can catalyze overall water splitting with a low cell voltage of 1.55 V and 100% Faradic efficiency, demonstrating its practical applications. The present work offers a new route for developing 1 T-MoS 2 based hybrid electrocatalysts with desirable surface and interface structure for energy storage and conversion. [Display omitted] • Self-supported 1 T-MoS 2 /Co 3 S 4 /Ni 3 S 2 nanoarrays was developed for overall water splitting. • The abundant interfaces and defects in 1 T-MoS 2 /Co 3 S 4 /Ni 3 S 2 benefit its catalytic activity. • 1 T-MoS 2 can accelerate electron transfer during the catalytic process. • 1 T-MoS 2 /Co 3 S 4 /Ni 3 S 2 exhibits low HER and OER overpotentials of 50 and 240 mV. • 1 T-MoS 2 /Co 3 S 4 /Ni 3 S 2 can drive full water splitting at 1.55 V with 100% Faradic efficiency. [ABSTRACT FROM AUTHOR]

• Co-Co 6 Mo 6 C 2 @NC nano polyhedron was synthesized using ZIF-67 as a precursor. • The Co 6 Mo 6 C 2 can significantly improve the OER catalytic activity of the catalyst. • The Co-Co 6 Mo 6 C 2 @NC-5 exhibits a low OER overpotential of 270 mV at 10 mA cm−2. • The Co-Co 6 Mo 6 C 2 @NC-5 exhibits a high ORR half-wave potential of 0.80 V. • The Co-Co 6 Mo 6 C 2 @NC can be used as a bifunctional electrocatalyst for Zn-air battery. A high effective bifunctional electrocatalyst was developed for rechargeable Zn-air batteries by rational integrating high active Co sites for ORR and Co 6 Mo 6 C 2 specie for OER. [Display omitted] To facilitate the development of rechargeable metal-air batteries, the exploration of high effective bifunctional electrocatalysts is essential. In this work, we report a facile strategy to synthesize N doped carbon (NC) encapsulated Co-Co 6 Mo 6 C 2 (Co-Co 6 Mo 6 C 2 @NC) nano polyhedron using ZIF-67 as a precursor and investigated its catalytic performance for both oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). The introduction of Co 6 Mo 6 C 2 into Co@NC can significantly improve the OER catalytic activity of the catalyst, while the high ORR catalytic activity of the catalyst is maintained. Specifically, Co-Co 6 Mo 6 C 2 @NC-5 shows a decent half-wave potential of 0.80 V for ORR, and a very low overpotential of 270 mV at 10 mA cm−2 for OER, demonstrating its bifunctional activity. The rechargeable Zn-air battery assembled using Co-Co 6 Mo 6 C 2 @NC-5 exhibits a maximum power density of 90.75 mW cm−2 and a high specific capacity of 768 mA h g−1, as well as good durability of 50 h without attenuation in performance, highlighting its practical application. [ABSTRACT FROM AUTHOR]

CoS 2 @MoS 2 @NiS 2 nano polyhedron with double-shelled structure was demonstrated to have multiple catalytic activity for HER, OER and ORR, which could serve as highly efficient catalysts for both rechargeable Zn-air batteries and overall water spitting. [Display omitted] • Double shelled hollow CoS 2 @MoS 2 @NiS 2 polyhedron was synthesized using a self-template method. • The CoS 2 @MoS 2 @NiS 2 exhibits multiple catalytic activity for HER, OER and ORR. • The CoS 2 @MoS 2 @NiS 2 exhibits a low HER overpotential of 156 mV at 10 mA cm−2. • The OER and ORR performance was demonstrated by rechargeable Zn-air battery. • The Zn-air battery can effectively drive water splitting device catalyzed by CoS 2 @MoS 2 @NiS 2. Electrocatalysts play important role in various energy conversion and storage devices. The catalytic performance of electrocatalysts can be enhanced through the increasement of intrinsic catalytic activity by optimizing electronic structure and the improvement of exposed active sites by designing proper nanostructures. In this work, CoS 2 @MoS 2 @NiS 2 nano polyhedron with double-shelled structure was prepared using metal organic framework as a precursor. Due to the rational integration of multifunctional active center, the strong electronic interaction of the various component, the high electrochemical surface area and shortened mass transport induced by the special structure, CoS 2 @MoS 2 @NiS 2 exhibits high catalytic activity for hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). Specifically, low overpotentials of 156 and 200 mV was achieved to deliver a current density of 10 mA cm−2 for HER and OER, and a high half-wave potential of 0.80 V was observed for ORR. More importantly, the Zn-air battery assembled by CoS 2 @MoS 2 @NiS 2 exhibits a high-power density of 80.28 mW cm−2 and could effectively drive overall water splitting. This work provides a new platform for designing multifunctional catalysts with high activity for energy conversion and storage. [ABSTRACT FROM AUTHOR]

Abstract Oxygen evolution reaction (OER) plays a key role in electrochemical splitting of water and it is urgent to develop high-performance and cost-effective OER catalysts. In this work, we report the synthesis of V-Co/CoO@C nanorod as highly efficient OER catalysts. The V 2 O 5 nanowire and metal organic framework composite leads to the successful preparation of the catalyst. The V 2 O 5 nanowire not only induces the formation of Co/CoO species, but also facilitates uniform V doping. When used as OER catalyst, the V-Co/CoO@C nanorod only needs a low overpotential of 320 mV to achieve a high current density of 10 mA·cm−2. Graphical abstract Unlabelled Image Highlights • Porous V-Co/CoO@C nanorod was synthesized by using a V 2 O 5 @ZIF-67 as precursor. • The V-Co/CoO@C nanorod shows high OER activity of 10 mA·cm−2 at a η value of 320 mV. • The use of V 2 O 5 lead to the formation of Co/CoO and V doping. • The Co/CoO species and uniform V doping contributed to its OER performance. [ABSTRACT FROM AUTHOR]

Abstract The oxygen reduction reaction (ORR) is one of the core reactions that occur in fuel cells and metal air batteries. Metal-free catalysts such as porous carbons are promising candidates for ORR and the performance of porous carbons strongly depends on their nanostructure. Herein, we reported the synthesis of high surface area N doped carbon nanotube (CNT-900) by using ZnO@zeolite imidazolate framework (ZnO@ZIF-8) nanowire as a precursor. When used for an ORR catalyst, the CNT-900 show obvious superior performance compared with the carbon derived from ZIF-8. In addition, it exhibits comparable activity with 20 wt% Pt/C and superior stability. Combined with green and facile synthesis strategy, the method in this work can be easily extended to synthesis other nanomaterials for energy storage and conversion application. Graphical abstract N doped carbon nanotube with high surface area and ORR performance was synthesized by using ZnO@ZIF-8 nanowire as precursor. Unlabelled Image Highlights • ZnO@ZIF-8 was facilely synthesized at room temperature and converted to N doped carbon nanotube at 900 °C. • The CNT-900 shows very high surface area, which greatly improves its ORR performance. • The CNT-900 exhibits comparable activity with 20 wt% Pt/C and superior stability. [ABSTRACT FROM AUTHOR]

• MoO 2 @MoS 2 @Co 9 S 8 heterostructure nanorod by utilizing MoO 3 @ZIF-67 as a precursor. • The nanorod is assembled by 2D nanosheet with high electrochemical surface area. • The nanorod can serve as bifunctional electrocatalyst for overall water splitting. • The HER and OER overpotentials at 10 mA cm−2 are 160 mV and 310 mV. • The high performance is induced by the synergistic effect of the heterostructure. Developing low-cost and high-efficiency bifunctional catalysts for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) to catalyze electrochemical overall water splitting is critical for the production of hydrogen. Herein, we develop an in-situ reduction and vulcanization strategy to prepare MoO 2 @MoS 2 @Co 9 S 8 heterostructure nanorods by utilizing MoO 3 @ZIF-67 as a precursor. The reduction of MoO 3 can produce more conductive MoO 2 , and the vulcanization reaction can produce highly active MoS 2 for the HER as well as highly active Co 9 S 8 for the OER. In addition, the MoS 2 anchor on the MoO 2 not only facilitates electron transfer, but also interacts with Co 9 S 8 to induce a synergic catalytic effect by the electron transfer between them. Moreover, the 2D nanosheet assembled heterostructure nanorods can provide a large electrochemical surface area. Therefore, the merits of the materials are fully utilized and outstanding catalytic performances are achieved. MoO 2 @MoS 2 @Co 9 S 8 can catalyze HER and OER effectively with overpotentials of 160 and 310 mV at 10 mA cm−2, indicating its bifunctional activity. In addition, the two electrode electrolyzer catalyzed by MoO 2 @MoS 2 @Co 9 S 8 can reach 10 mA cm−2 current density at a cell voltage of 1.62 V with very high stability, demonstrating its practical application for water splitting. [ABSTRACT FROM AUTHOR]

• ZnS decorated N, S co-doped porous carbon polyhedron are synthesized. • A small fraction of ZnS can greatly improve the ORR activity of the catalyst. • The ZnS@NC-3 shows comparable ORR activity with 20 wt% Pt/C catalyst. • The Zn-air battery using ZnS@NC-3 shows an open circuit voltage of 1.524 V. • The Zn-air battery exhibit a power density of 176 mW cm−2 and a specific capacity of 736 mA h g−1. Developing low cost, environmentally friendly and high efficiency oxygen reduction reaction (ORR) electrocatalysts is critical for clean energy conversion and storage devices including fuel cells and metal-air batteries. Herein, we developed a facile method to doping N, S and ZnS into carbon framework simultaneously. The N, S co-doping and extra ZnS active sites could prominently enhance the ORR performance of the carbon. The optimized sample ZnS@NC-3 exhibit an onset potential of 0.94 V and a half-wave potential of 0.84 V, which is comparable to 20 wt% Pt/C. In addition, the methanol tolerance and cycle ability are obvious superior than that of Pt/C. Moreover, when used as electrocatalysts for Zn-air battery, the battery exhibits an open circuit voltage of 1.524 V, a high specific capacity of 736 mA h g−1 and a max power density of 176 mW cm−2, demonstrating its great potential for clean energy conversion. [ABSTRACT FROM AUTHOR]

Designing efficient oxygen evolution reaction (OER) electrocatalysts is crucial for practical applications in water splitting and metal-air battery devices. Special structures of materials often bring in unprecedented catalytic activity. Herein, we first report the synthesis of CoMoO 4 nanotube by using MoO 3 @ZIF-67 nanorod. The CoMoO 4 nanotube shows high OER activity with a low overpotential of 315 mV delivering a current density of 10 mA cm−2. The electro-catalytic activity surpasses that of many Co and Mo-based catalysts. Furthermore, the strategy presented here is facile, and can be extended to the synthesis of other Mo-based nanotube materials for energy storage and conversion. Unlabelled Image • CoMoO 4 nanotube was prepared by using MOF composite as precursor for the first time. • The CoMoO 4 shows high a specific surface area of 157 m2 g−1. • The CoMoO 4 shows high OER activity of 10 mA cm−2 at an overpotential of 315 mV. • The CoMoO 4 also shows outstanding long-term electrochemical durability. [ABSTRACT FROM AUTHOR]