Achieving highly active A-site cation-deficient perovskite electrocatalysts operated at large current density toward hydrogen evolution reaction

A-site cation-deficient strategy is proposed to develop highly active perovskite electrocatalysts toward hydrogen evolution reaction (HER). Herein, La and Ba co-deficient (LaBa)1-xCo2O5+δ perovskites are evaluated as the potential HER catalysts, demonstrating desirable catalytic performance in alkaline media. Caused by enhanced conductivity, moderate Co valence state, strong affinity with molecular H2O, and outstanding operating stability at large current density (J), (LaBa)0.95Co2O5+δ (LBCO-95) only requires low overpotential (η) of −415 mV to drive a J of 1000 mA cm-2 geo. A small Tafel slope of −47.4 mV dec−1 manifests the Volmer-Heyrovsky mechanism in the LBCO-95 catalyst. Noticeably, LBCO-95 outperforms the state-of-the-art Pt/C in some aspects. As for the realistic water electrolysis, our designed electrolyzer with cathodic LBCO-95 and anodic NiFe-layered double hydroxide (NiFe-LDH) delivers an operating voltage of 1.97 V at 500 mA cm−2, which is better than commercially available Pt/C and IrO2 couple (2.16 V).