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The oxygen evolution reaction (OER) is an important half-reaction in rechargeable metal–air batteries and water splitting devices, and it suffers from slow kinetics due to the multiple step proton-electron coupled process. Therefore, the major challenge for the OER is to develop durable and low-cost electrocatalysts with high catalytic performance. Herein, a ternary metal CoNiFe subacetate nano prism (CoNiFe NP) was synthesized by a one-step hydrothermal method, with the aim of accelerating the water dissociation and improving the reaction rate using the synergy of the ternary metal. The results show that the electrocatalytic performance of the ternary metal CoNiFe layered double hydroxide is significantly improved compared with the binary metal and single metal catalysts. In particular, the overpotential of the prepared CoNiFe NP for the OER at 10 mA cm−2 is as low as 292 mV, and the Tafel slope is 75.6 mV dec−1. This work provides a new platform for the design of medium-entropy electrocatalysts using the interaction of polymetallic components. [ABSTRACT FROM AUTHOR]

Nano bowl-like Co–Co6Mo6C2 coated by N,P co-doped carbon (Co–Co6Mo6C2@NPC) is reported as an electrocatalyst for Zn–air batteries. Co–Co6Mo6C2@NPC only needs an overpotential of 210 mV at 10 mA cm−2 for the OER, and the half-wave potential for the ORR is 0.81 V. In addition, the Co–Co6Mo6C2@NPC based battery shows a large open-circuit voltage of 1.335 V and a maximum power density of 160.5 mW cm−2, as well as good stability. The improved catalytic performance can be ascribed to the co-existence of Co6Mo6C2 and Co species to improve the intrinsic catalytic activity, and the bowl-like nanostructure to facilitate the mass transfer. [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]

Developing high‐efficiency bifunctional electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) to realize low‐cost water splitting is the premise for large‐scale production of hydrogen. The catalytic activity of an electrocatalysts greatly depends on its composition and structure. In this work, we report the preparation of hollow CoS2/MoS2 heterostructure using ZIF‐67 as the precursor. The ratio of Co and Mo are optimized to maximize the synergy of CoS2 and MoS2, due to their specific catalytic activity for OER and HER. The optimized CoS2/MoS2 exhibits good bifunctional catalytic activity in view of its low overpotentials for HER (170 mV) and OER (270 mV), as well as small cell voltage of 1.66 V for overall water splitting. This work provides a facile strategy to controllable fabrication of efficient bifunctional electrocatalysts for renewable energy applications. [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]

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]

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]

• 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]

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]