Cu-doped La_0.5Sr_0.5CoO_3- perovskite as a highly efficient and durable electrocatalyst for hydrogen evolution

The preparation of a high-efficiency and durable electrocatalyst for the alkaline hydrogen evolution reaction (HER) is essential for realizing renewable energy technologies. Herein, a series of La_0.5Sr_0.5CoO_3- perovskites with different amounts of Cu cations substituting at B-sites were fabricated for the HER. Specifically, the optimized La_0.5Sr_0.5Co_0.8Cu_0.2O_3- (LSCCu_0.2) exhibits a significantly enhanced electrocatalytic activity with an ultralow overpotential of 154 mV at 10 mA cm^-2 in 1.0 M KOH, which is reduced by 125 mV compared with that of pristine La_0.5Sr_0.5CoO_3- (LSC, 279 mV). It also delivers a robust durability with no obvious degradation after 150 h. Impressively, the HER activity of LSCCu_0.2 is superior to that of commercial Pt/C at large current densities (>270 mA cm^-2). XPS analysis indicates that Co²⁺ ions replaced by an appropriate amount of Cu²⁺ ions can increase the proportion of Co³⁺ and generate high content of oxygen vacancies in LSC, which leads to an increased electrochemically active surface area, thereby greatly facilitating the HER. This work offers a simple way for the rational design of cost-effective and highly efficient catalysts, which may be extended to other Co-based perovskite oxides for the alkaline HER.