Modulating MOF-derived cobalt nickel selenide via vacancies to accelerate water dissociation for efficient alkaline water electrolysis

Abstract

Transition-metal selenide materials have gained attention as effective electrocatalysts for the hydrogen evolution reaction (HER). However, the performance of existing selenide catalysts has often been limited due to the slow reaction kinetics. In this study, we design a cobalt–nickel selenide heterostructured catalyst with selenium vacancies (CoNiSe_x). This catalyst was synthesized by selenizing a cobalt–nickel bimetallic zeolitic imidazolate framework (CoNi ZIF) precursor, followed by annealing in a reducing atmosphere. Due to the heterostructure and modified electronic environment, this CoNiSe_x catalyst demonstrated remarkable HER activity, attain to the current density of 10 mA cm⁻² at a low overpotential of 142 mV, which significantly outperforms most reported transition-metal selenide electrocatalysts during alkaline HER. Electrochemical experiments and electronic structure analyses indicate that the synergistic effects from the heterostructure and selenium vacancies optimize electron redistribution between cobalt and nickel sites. This optimization greatly improves water dissociation, thus accelerating the alkaline HER process.