Evaluation of A-Site Ba2+-Deficient Ba1−xCo0.4Fe0.4Zr0.1Y0.1O3−δ Oxides as …

Exploring earth-abundant and cost-effective catalysts with high activity and stability for a hydrogen evolution reaction (HER) is of great importance to practical applications of alkaline water electrolysis. Here, we report on A-site Ba 2+ -deficiency doping as an effective strategy to enhance the electrochemical activity of BaCo 0.4 Fe 0.4 Zr 0.1 Y 0.1 O 3− δ for HER, which is related to the formation of oxygen vacancies around active Co/Fe ions. By comparison with the benchmarking Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3− δ , one of the most spotlighted perovskite oxides, the Ba 0.95 Co 0.4 Fe 0.4 Zr 0.1 Y 0.1 O 3− δ oxide has lower overpotential and smaller Tafel slope. Furthermore, the Ba 0.95 Co 0.4 Fe 0.4 Zr 0.1 Y 0.1 O 3− δ catalyst is ultrastable in an alkaline solution. The enhanced HER performance originated from the increased active atoms adjacent to oxygen vacancies on the surface of the Ba 0.95 Co 0.4 Fe 0.4 Zr 0.1 Y 0.1 O 3− δ catalyst induced by Ba 2+ -deficiency doping. The low-coordinated active atoms and adjacent oxygen ions may play the role of heterojunctions that synergistically facilitate the Volmer process and thus render stimulated HER catalytic activity. The preliminary results suggest that Ba 2+ -deficiency doping is a feasible method to tailor the physical and electrochemical properties of perovskite, and that Ba 0.95 Co 0.4 Fe 0.4 Zr 0.1 Y 0.1 O 3− δ is a potential catalyst for HER.