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

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.