VOx-doped CoP catalysts with synergistic dual-active configuration for boosting hydrogen evolution kinetics

Abstract

Hydrogen evolution reaction (HER), is of great significance to harvest H2 via energy-saving alkaline water electrolysis yet still challenging. Integrating heterogeneous materials is effective in designing favorable electrocatalysts for water dissociation (WD) and H-immediate involved adsorption/desorption behavior and triggering positive interactions to break the kinetics limitation. Herein, a promising configuration of a vanadium-oxide species integrated with cobalt-phosphide plane that grown on the nickel foam (labeled as VOx-CoP/NF), is demonstrated to boost the alkaline HER kinetics comprehensively. The doped vanadium-oxide species preferentially perform the WD process to generate H-intermediates. Meanwhile, interaction between VOx and CoP induce the electronic redistribution that optimizes 3d-2p orbital hybridization state, which balances the adsorption strength of H* to facilitate the hydrogen transfer and enrichment. Eventually, VOx-CoP/NF exhibits supereminent alkaline HER performance with an overpotential of only 65/245 mV at 10/400 mA cm−2, superior to individual CoP and most representative cobalt-phosphide candidates. A flowing anion exchange membrane (AEM) urea-assisted water electrolyzer with VOx-CoP/NF as a bifunctional catalyst, is assembled and achieves a satisfactory performance, verifying its practical feasibility for efficient H2 production. The concept exemplified in this work is that synchronous optimization of elementary reaction step kinetics of HER through reasonable constructing well-defined configuration is instructive for the design of HER electrocatalysts.