Tuning Interfacial Active Sites over Porous Mo<sub>2</sub>N-Supported Cobalt Sulfides for Efficient Hydrogen Evolution Reactions in Acid and Alkaline Electrolytes
Yan Zang, Baopeng Yang, An Li, Chengan Liao, Gen Chen, Min Liu, Xiaohe Liu, Renzhi Ma, Ning Zhang
Abstract
Although various cobalt-sulfide-based materials have been reported for the hydrogen evolution reaction, only a few have achieved high activity in both acid and alkaline electrolytes due to the inherent poor conductivity and low active sites. In this work, a heterojunction of cobalt sulfide and Mo2N is designed for efficient hydrogen evolution reactions in both acid and alkaline electrolytes. X-ray photoelectron spectroscopy reveals that Mo–S bonds are formed at the interface between Mo2N and CoS2, which result in the fabricated Mo2N/CoS2 materials exhibiting a considerably enhanced hydrogen evolution reaction activity than the corresponding Mo2N, CoS2, and most reported Mo- and Co-based catalysts in electrolytes of H2SO4 and KOH solutions. Density functional theory calculations suggest that the redistribution of charges occurs at the heterointerface. In addition, the interfacial active sites possess a considerably lower hydrogen adsorption Gibbs free energy than those atoms that are far away from the interface, which is beneficial to the process of hydrogen evolution reaction. This study provides a feasible strategy for designing hetero-based electrocatalysts with a tuned highly active interface.