Hydrogen spillover in CoNi/CoNiMo3O8 Mott-Schottky heterostructure facilitates ampere-level hydrogen generation

Abstract

Alkaline water electrolysis is a low-cost and sustainable hydrogen production technology, and the proper design of an active hydrogen evolution reaction (HER) catalyst is crucial. Interfacial modulation is an effective strategy for accelerating the electron and mass transfer rates in the HER, which leads to a significant decrease in the energy required for water splitting, particularly at ampere-level current densities. Herein, we report an in-situ constructed CoNi/CoNiMo₃O₈ Mott-Schottky electrocatalyst characterized by superwetting properties. Both experimental and density functional theory (DFT) calculations indicated that the built-in electric field (BEF) formed at the heterostructure interface can optimize the adsorption and desorption behavior of reaction intermediates and facilitate the hydrogen spillover process on CoNi/CoNiMo₃O₈. Accordingly, the CoNi/CoNiMo₃O₈ electrode exhibited superior HER activity, featuring a commendably low overpotential of 267 mV at 1000 mA cm⁻² and a durable operation for 650 h under alkaline conditions. An anion-exchange membrane (AEM) electrolyzer using CoNi/CoNiMo₃O₈ as the cathode demonstrated exceptional performance, which reached a current density of 1000 mA cm⁻² at 2.03 V and 60 °C. Our findings delineate a potential pathway for the design of high-performance and efficient Mott-Schottky electrocatalysts, offering a significant leap forward in the development of energy-efficient electrolytic systems for industrial hydrogen production.