A heterogeneous interface promotes the efficient oxygen evolution of N-rGO/Co0.5Ni0.5Se2−xNx/NF

Abstract

Co–Ni-based nanomaterials, as one of the candidate materials for oxygen evolution reaction (OER), have been widely studied. However, their unsatisfactory activity and poor durability seriously hinder their practical applications. Nitrogen-doped cobalt–nickel diselenide (Co_0.5Ni_0.5Se_2−xN_x) composites (N-rGO/Co_0.5Ni_0.5Se_2−xN_x/NF-100) were fabricated on a three-dimensional conductive substrate of a nitrogen-doped reduced graphene oxide/nickel foam (N-rGO/NF) by a hydrothermal method. N-rGO/NF not only provides good conductivity and ion transport pathways for the electrocatalyst but also limits the size of Co_0.5Ni_0.5Se_2−xN_x, increases the specific surface area of the electrocatalyst, and promotes the OER process. The heterogeneous interface interactions confer upon them a better OER performance than those of the orthogonal-phase CoSe₂ and cubic-phase NiSe₂. Doping nitrogen into selenides can cause lattice distortion and enhance the adsorption energy of electrocatalysts for intermediates. Density functional theory (DFT) calculations confirm that the method of constructing heterogeneous interfaces can regulate the adsorption energy of the catalyst for the OER intermediates, thereby reducing the overpotential of the electrocatalyst. The prepared N-rGO/Co_0.5Ni_0.5Se_2−xN_x/NF-100 has a low overpotential of 228.85 mV at a current density of 10 mA cm⁻² and a long-term stability of more than 72 hours, providing a new perspective for the design and preparation of highly active and stable OER electrocatalysts.