NiSe-modified CoMoO4 nanosheets as bifunctional electrocatalysts for hydrogen and oxygen evolution reactions

Selecting self-supporting substrates with large specific surface areas is an effective strategy to avoid the agglomeration of nanomaterials and improve the structural stability of materials while increasing their electrical conductivity. In this study, CoMoO4 nanosheet structures were first grown on a nickel foam (NF) substrate by hydrothermal and calcination processes. Then, NiSe nanoparticles were deposited on NF/CoMoO4 by a constant potential method to construct NF/CoMoO4 @NiSe nanosheet electrode materials with graded layered structures. This nanosheet structure grown on NF substrates provided enough space for mass transfer and fully exposed the electrochemical active sites. Meanwhile, the self-supported electrode reduced the indirect contact resistance between the electrocatalyst and the substrate, which promoted the timely release of generated bubbles from the electrode. The NF/CoMoO4 @NiSe electrode exhibited excellent hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) electrocatalytic activities under alkaline conditions. Overpotentials of only 58 mV and 184 mV were needed to achieve a current density of 10 mA·cm−2 for the HER and OER, respectively. This study presents new ideas for the construction of nanosheet structures and the design of efficient HER and OER bifunctional electrocatalysts using transition metal selenides.