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The rational design of high-efficiency electrocatalysts for application in water oxidation in alkaline media remains a great challenge. In this paper, Ni3+-rich nanograss-like Mo-doped Ni3S2/NiS/VS arrays grown on nickel foam (denoted as Mo-NiVS@NF) have been successfully constructed through a hydro/solvothermal method. Interestingly, Mo-NiVS@NF exhibits superior catalytic OER performance, needing an overpotential of 217 mV to drive a current density of 10 mA cm−2, outperforming most previously reported NiS-based electrocatalysts. The result indicates that the Ni3+-rich active sites caused by the modulation of the electronic structure environment via the introduction of V and high-valency Mo play an important role in the high activity for the OER. Moreover, this catalyst shows high long-term electrochemical durability. [ABSTRACT FROM AUTHOR]

Exploring active catalyst components is very important to develop high-performance and highly stable ORR electrocatalysts to replace costly Pt-based catalysts, though it remains an ongoing challenge. In this paper, three ORR catalysts with different active components were obtained by calcination of different proportions of mixed precursors simply and delicately. Among them, precursor 1 (bimetallic polymer Fe/Zn-ZIFs@ZnCO3) played the role of a self-sacrificing template, while precursor 2 (an N, P-co-doped polymer) played the role of a volatile atmosphere. Precursor 2 also embedded N and P heteroatoms into the carbon framework during high-temperature volatilization, which resulted in subtle changes in the active catalyst components. Finally, a hybrid of metal Fe and α-Fe2O3 nanoparticles embedded in N, P-codoped carbon nanotubes with many separated gullies (named α-Fe2O3/Fe@NPC) exhibited excellent ORR catalytic activity in an alkaline solution as compared to commercial Pt/C. This work provides a new strategy for designing controllable active components using volatile precursors. [ABSTRACT FROM AUTHOR]

Electrocatalytic water splitting, which is driven by renewable energy input to produce oxygen, has been widely regarded as a promising strategy in the future energy portfolio. The two-dimensional structure based on CoOOH nanosheets is easy to handle in the preparation process, low in cost, and has a small overpotential during water decomposition. Therefore, CoOOH two-dimensional materials have been widely used as electrocatalysts for the oxygen evolution reaction (OER). In this paper, we summarize the application of two-dimensional CoOOH nanosheets in the field of oxygen production from electrocatalytic water splitting. First, the different preparation methods of two-dimensional CoOOH nanosheets are briefly introduced. The structure–activity relationship of the two-dimensional CoOOH catalyst was analyzed from different viewpoints, such as doping, defects, etc. Finally, different catalytic mechanisms of CoOOH-based catalysts are discussed, and studies at the density functional theory (DFT) level are also provided to support the above mechanisms. To improve the readability of this review, a concise overview at the end of each section is given to illustrate some of the characteristics and trends of the studies in the corresponding part. The opportunities and challenges of two-dimensional CoOOH as an electrocatalyst in the future are summarized in the Conclusion section. This work will provide new insights and perspectives to the readers to understand the role of CoOOH nanosheets in the OER process. [ABSTRACT FROM AUTHOR]

It is highly desirable for porous coordination polymers (PCPs), including metal–organic frameworks (MOFs) and Prussian blue analogues (PBAs), to retain their intrinsic characteristics in electrocatalysis, instead of being used as precursors or templates for further total conversion to other compounds via high-temperature calcination. Here, a S-treated two-dimensional (2D) CoFe bimetallic PBA grown on carbon fiber paper (CFP) (named S-CoFe-PBA/CFP) is assembled and applied as a highly efficient oxygen evolution reaction (OER) electrocatalyst in 1 M KOH. The resultant S-CoFe-PBA/CFP demonstrates significantly improved OER catalytic activity; overpotentials of only 235, 259, and 272 mV are needed to drive current densities of 10, 50, and 100 mA cm−2, respectively, with a super low Tafel slope of 35.2 mV dec−1. Even more noteworthy, a current density of 90 mA cm−2 can be achieved when a potential of 1.5 V vs. RHE is applied, which is 6.4 times higher than that of commercial Ir/C in the same environment. The outstanding electrocatalytic performance can be ascribed to two reasons caused by the S-treatment process. On one hand, H+ from intermediates of *OH and *OOH can be captured by –SOx distributed on the surface of the catalyst, thus accelerating the breaking of O–H; on the other hand, partial phase transformation of CoFe-PBA leads to the in situ formation of amorphous CoSx nanogauze on the surface, and the resultant electronic interactions between the two phases contribute much to the improvement of charge transfer and adsorption for OER intermediates. This work provides a new avenue for the design of highly efficient PCP-based OER electrocatalysts. [ABSTRACT FROM AUTHOR]

We demonstrate a lamellar NiMoCo@CuS catalyst, showing not only an excellent catalyst performance (η100@72 mV and a Tafel slope of 47 mV dec−1), but also a good stability (20 mA cm−2@30 hours), outperforming the NiMo system and noble Pt. [ABSTRACT FROM AUTHOR]