Synergistically Enhanced Ni₃Co₁(OH)_x@Ni₃S₂ Heterojunction Catalyst for High-Performance Ethanol Electrooxidation

Abstract

Coupling the ethanol electrooxidation reaction (EOR) with the hydrogen evolution reaction is an effective way to obtain green energy. Although Ni-based catalysts have the characteristics of low cost and good stability, meanwhile, the activity needs to be further improved. Here, we report a Ni-based heterojunction EOR catalyst, Ni₃Co₁(OH)_x@Ni₃S₂, composed by two phases of Ni₃S₂ and Ni₃Co₁(OH)_x. The obtained Ni₃Co₁(OH)_x@Ni₃S₂ showed excellent EOR performance, which could achieve a high specific activity of 315.7 mA/cm² at 1.40 V, which was 15.5 times that of Ni(OH)₂ and superior to most reported Ni-based catalysts. The addition of Co regulates the d-band center and introduces additional positively charged centers for the strong adsorption of OH^-. The anionic effect of Ni₃S₂ can accelerate oxidation of the Ni active centers to active Ni(III) sites. The heterojunction structure can enhance the cation and anion effects and the turnover rate of OH^- species, improving the EOR performance.