The N-rGO/NF three-dimensional porous substrate and N-doped regulation of CoSe2 nanoneedles accelerate surface structure reconstruction to achieve efficient oxygen evolution

Electrocatalytic water splitting is a clean and sustainable method for hydrogen production. Cobalt diselenide (CoSe 2 ) is an electrocatalyst with great application prospects. However, due to the inherent low electrical conductivity and aggregation tendency of transition metal selenides, their practical applications are limited. In this study, under the constraint of three-dimensional porous nitrogen-doped reduced graphene oxide/nickel foam (N-rGO/NF) substrates, small-sized nitrogen-doped cobalt diselenide (CoSe 2-x N x ) nanoneedles were prepared by a one-step hydrothermal method, and excellent electrocatalysts were obtained. The optimized catalyst (N-rGO/CoSe 2-x N x /NF-100) exhibits excellent OER performance in an alkaline environment at current densities of 10, 50 and 100 mA cm −2 . N-rGO/NF not only provides good electrical conductivity for the electrocatalyst, but also limits the size of CoSe 2 . The three-dimensional porous structure constructed by small-sized CoSe 2 nanoneedles increases the specific surface area of the electrocatalyst, which is conducive to the OER process. The doping of nitrogen in CoSe 2 forms Co-Nx electron transfer channels, accelerating charge transfer. Density functional theory (DFT) calculations have confirmed that structural modification methods such as limiting the size of the electrocatalyst to avoid agglomeration, as well as electronic control methods such as nitrogen doping, can accelerate the surface structure reconstruction process of the catalyst, thereby improving the adsorption energy of the electrocatalyst for OER intermediates and reducing the overpotential.