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Continuous oxygen vacancy engineering of the Co₃O₄ layer for an enhanced alkaline electrocatalytic hydrogen evolution reaction

Zhang, Haoxuan, Zhang, Jiahao, Li, Yuhang, Jiang, Haibo, Jiang, Hao, Li, Chunzhong
Journal of materials chemistry A 2019 v.7 no.22 pp. 13506-13510
adsorption, catalysts, cobalt, cobalt oxide, electrochemistry, foams, hydrogen production, melting, melting point, nickel, oxygen, reaction kinetics
Precisely tailoring the oxygen vacancies (Oᵥ) of Co oxide based electrocatalysts could be highly essential for boosting hydrogen evolution reaction (HER) performance in alkaline media. Here, a rapid synthesis of an Oᵥ-engineered Co₃O₄ layer on Ni foam has been demonstrated through a solid-phase melting strategy, where the Oᵥ content in the Co₃O₄ layer can be adjusted from 52% to 74% simply by changing melting temperature. After HER testing, this content is further adjusted to 22–45% with the same trend. Remarkably, the Co₃O₄ layer with a medium Oᵥ content (32%) gives the highest mass activity of −2.12 A g⁻¹ at an overpotential of 200 mV for the alkaline electrocatalytic HER. Moreover, it only requires an ultrasmall overpotential of 203 mV to achieve −100 mA cm⁻², outperforming all reported Co₃O₄ electrocatalysts so far. The medium Oᵥ content in the Co₃O₄ electrocatalyst could enhance reaction kinetics by optimizing catalytic intermediate adsorption during the alkaline HER. This feasible tactic to precisely control Oᵥ may provide an avenue for exploring other advanced electrocatalysts.