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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]

Electrochemical nitrogen reduction reaction (NRR), as a green and sustainable ammonia (NH3) synthesis process, is considered to be the most promising alternative to the traditional Haber‐Bosch method for NH3 synthesis. However, this process requires a highly active electrocatalyst to overcome the problems of low NRR activity and selectivity. Herein, we deposited metallic bismuth nanoparticles on two‐dimensional Ti3C2 MXene nanosheets by a simple liquid phase reduction method to synthesize Bi@Ti3C2 nanocomposites. This composite material is a promising electrocatalyst for environmental electrocatalytic N2 fixation to NH3. Unexpectedly, the Bi@Ti3C2 composite obtains an excellent NH3 yield and Faraday efficiency as high as 28.3 μg h−1 cm−2 and 27.2 % at −0.4 V versus reversible hydrogen electrode (RHE) in 0.1 M KOH. The high NRR activity can be attributed to the unique N‐philic and H‐phobic characteristics of Bi atoms and the outstanding electronic conductivity of MXene. Moreover, the Bi@Ti3C2 composite catalyst also exhibited good cycling stability and durability of up to 24 h. This work highlights the potential importance of material design and will also expand the research and exploration of high‐efficiency NRR electrocatalysts. [ABSTRACT FROM AUTHOR]

As an energy‐saving and environmentally friendly ammonia synthesis method, electrocatalytic nitrogen reduction reaction (NRR) has received a great deal of attention. There is thus an urgent need to find high‐efficiency electrocatalysts for the NRR. In this work, a Cu/Ti3C2 composite catalyst was prepared and demonstrated excellent selectivity under environmental conditions, which could efficiently convert N2 into NH3 electrochemically. In 0.1 M KOH, Cu/Ti3C2 can achieve a high Faradaic efficiency of 7.31 % and a high NH3 production rate of 3.04 μmol h−1 cm−2 at −0.5 V vs. RHE. Moreover, the material also exhibits superior electrochemical stability and durability. At the same time, density functional theory (DFT) shows that, compared with Ti3C2, Cu/Ti3C2 exhibits a wider conduction and valence band and a larger Fermi level, thus indicating that Cu plays a vital role in the enhancement of the catalytic activity and conductivity of Ti3C2‐based materials. This work provides a feasible strategy for designing high‐efficiency MXene‐based NRR electrocatalysts. [ABSTRACT FROM AUTHOR]

Electrocatalytic nitrogen reduction reaction (NRR), as a potential alternative to industrial ammonia synthesis (Haber‐Bosch method), can achieve "green" and sustainable ammonia production under environmental conditions. However, the NRR process is still limited by the slow cleavage of the N≡N triple bond and the existence of a competitive hydrogen evolution reaction. For this reason, many researchers have studied the construction and synthesis of high‐efficiency nitrogen reduction electrocatalysts. Herein, a Co‐based metal‐organic framework (ZIF‐67) was used to prepare Co/C‐900 composites through high‐temperature pyrolysis (900 °C) for ammonia synthesis under environmental conditions. The Co/C‐900 catalysts exhibited excellent NRR performance, with a high NH3 yield of 4.66 μmol cm−2 h−1 at −0.3 V (vs. RHE) and a faradaic efficiency of 11.53 % in 0.1 M potassium hydroxide. This work provides a simple strategy for the design of porous, non‐noble‐metal electrocatalysts for electrochemical NRR. [ABSTRACT FROM AUTHOR]

The family of transition metal carbides, nitrides, and carbonitrides (collectively called MXenes) has been a thriving field since the first invention of Ti3C2Tx (MXene) in 2011. MXene is a new type of nanometer 2D sheet material, which exhibits great application potentials in various fields due to its multiple advantages such as high specific surface area, good electrical conductivity, and high mechanical strength. Electrocatalysis is regarded as the core of future clean energy conversion technologies, and MXene‐based materials provide inspiration for the design and preparation of electrocatalysts with high activity, high selectivity, and long loading life time. The applications of MXene‐based materials in electrocatalysis, including hydrogen evolution reaction, nitrogen reduction reaction, oxygen evolution reaction, oxygen reduction reaction, carbon dioxide reduction reaction, and methanol oxidation reaction are summarized in this review. As a crucial session regarding experiments, the current safer and more environmentally friendly preparation methods of MXene are also discussed. Focusing on the materials design and enhancement methods, the key challenges and opportunities for MXene‐based materials as a next‐generation platform in both fundamental research and practical electrocatalysis applications are presented. This account serves to promote future efforts toward the development of MXenes and related materials in the electrocatalysis applications. [ABSTRACT FROM AUTHOR]

Ammonia, one of the most important chemicals and carbon‐free energy carriers, is mainly produced by the traditional Haber–Bosch process operated at high pressure and temperature, which results in massive energy consumption and CO2 emissions. Alternatively, the electrocatalytic nitrogen reduction reaction to synthesize NH3 under ambient conditions using renewable energy has recently attracted significant attention. However, the competing hydrogen evolution reaction (HER) significantly reduces the faradaic efficiency and NH3 production rate. The design of high‐performance electrocatalysts with the suppression of the HER for N2 reduction to NH3 under ambient conditions is a crucial consideration for the development of electrocatalytic NH3 synthesis with high FE and NH3 production rate. Five kinds of recently developed electrocatalysts classified by their chemical compositions are summarized, with particular emphasis on the relationship between their optimal electrocatalytic conditions and NH3 production performance. Conclusions and perspectives are provided for the future design of high‐performance electrocatalysts for electrocatalytic NH3 production. The Review can give practical guidance for the design of effective electrocatalysts with high FE and NH3 production rates. [ABSTRACT FROM AUTHOR]

TaO‐ and TaC‐based nanocomposites as novel and low‐cost counter electrodes (CEs) in dye‐sensitized solar cells (DSCs) show outstanding electrocatalytic activity and photovoltaic performance, superior to the Pt electrode. Based on the first‐principles density functional theory (DFT) calculations, I3 is chemisorbed onto the TaO surface as opposed to physical adsorption on the TaC surface. The TaO‐based composite is more efficient than the TaC‐based composite as a CE in DSCs. [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]

[Display omitted] • Overview of Cu-based catalysts for ECR with C 2+ products are presented. • In-depth discussion of electrochemical synthesized Cu based catalysts with different types. • Outline of the ordinary methods combined with electrochemical synthesis for Cu based catalysts. • Perspective on the development potential of electrochemical synthesized Cu based catalysts for ECR. In recent decades, catalytic reduction of CO 2 is a hot topic in the research field of electrocatalysis. Copper is the only metal catalyst capable of producing multiple carbon (C 2+) products in electrocatalytic CO 2 reduction (ECR), however, there are still many challenges such as low selectivity, serious hydrogen evolution (HER) and poor stability. So far, various synthesis methods have been developed for Cu-based catalysts. Compared with ordinary chemical synthesis, electrochemical method has the advantages of simple process, controllable conditions, good safety and eco-friendly. In this review, the recent progress in synthesizing different types of Cu-based catalysts by means of the electrochemical method are comprehensively reviewed. The engineering strategies and the effects of the key preparation conditions on the catalytic performance of CO 2 electroreduction for C 2+ products are discussed in details. Besides, copper-based catalysts synthesized by electrochemical methods combined with the ordinary methods (wet chemical methods, plasma activated methods and other methods) were also outlined. Finally, the development potential of electrochemical synthesis for Cu-based catalysts are recommended, which provides a direction for the future development of Cu-based catalysts with low cost and high ECR performance. [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]

The sluggish anodic oxygen evolution reaction (OER) greatly hinders the working efficiency of electrochemical water splitting to produce hydrogen, and it is therefore important to explore high-performance and cost-effective OER catalysts. In this communication, we report the synthesis of cobalt boride incorporated within porous carbon using a metal–organic framework (MOF) as a precursor. The high catalytic activity of Co–B and the high conductivity of carbon both contribute to the OER catalytic activity of Co–B/C. When used as an OER catalyst, this material shows high catalytic activity, delivering a current density of 10 mA cm − 2 at a low overpotential of 320 mV, as well as outstanding long-term electrochemical durability. This finding is of fundamental and practical importance as it not only extends the application of MOFs, but also introduces a new method for synthesizing highly efficient OER electrocatalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] • V-Co@CNT was synthesized by one-step calcination. • V-Co@CNT shows excellent MOR activity. • The introduce of dicyandiamide is beneficial to provide more oxygen vacancies, then improving MOR activity. Synthesis of highly active and durable electrocatalysts is very important to enhance the reaction rate of methanol oxidation reaction (MOR). Herein, we reported the synthesis of vanadium-doped cobalt nanoparticles trapped in carbon nanotube (V-Co@CNT), which was realized through one-step calcination of Zeolitic Imidazolate Framework-67 (ZIF-67) grown on V 2 O 5 nanorods (V 2 O 5 @ZIF-67) with the assistance of dicyandiamide (DCDA). The results of experiment verified that because of the appearance of lower valence vanadium during the carbonization of DCDA, the synthesized V-Co@CNT shows better MOR performance than V-Co@CNR (direct carbonization of V 2 O 5 @ZIF-67 without using DCDA) in 1 M KOH + 1 M CH 3 OH. For the MOR||HER test, at 1.45 V, V-Co@CNT shows an excellent stable current density of 7 mA/cm2. [ABSTRACT FROM AUTHOR]

Abstract: The Pt-like electrocatalytic activity of counter electrodes (CEs) prepared from tantalum oxides for dye-sensitized solar cells (DSCs) is demonstrated. The low ratio of oxygen to metal atom of the oxide favors the electrocatalytic activity of these CE materials for I3 − reduction in DSCs. TaO, used as a CE in DSCs, shows superior electrocatalytic activity and a high power conversion efficiency of 6.48%, up to 90.5% of the level obtained using Pt as a CE (7.16%). This work develops the use of novel tantalum oxide CE materials for low cost and high efficiency DSCs. [Copyright &y& Elsevier]

• 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]