Constructing Dual Active Sites via Cu Doping in Perovskite for Boosting Electrochemical Hydrogen Evolution

Perovskites with tunable compositions and structures are desirable electrocatalysts for water electrolysis. However, achieving efficient hydrogen evolution reaction (HER) in alkaline media using perovskite-based catalysts remains a significant challenge. Herein, a Cu-doped La 0.5 Ba 0.5 CoO 3–δ perovskite was synthesized via a sol-gel method, which exhibits enhanced HER electrocatalytic activity through the construction of dual active sites. X-ray photoelectron spectroscopy (XPS) and x-ray absorption fine structure (XAFS) analyses reveal that Cu doping simultaneously induces the oxidation of Co and the formation of oxygen vacancies, establishing a synergistic charge compensation between the dual active sites. Specifically, oxygen vacancies promote water dissociation by enhancing adsorption, while high-valence Co species reduce charge transfer resistance, thereby facilitating electron transfer during HER. As a result, the optimized La 0.5 Ba 0.5 Co 0.8 Cu 0.2 O 3–δ (LBCC 0.2 ) achieves low overpotentials of 160 mV and 228 mV at current densities of 10 and 100 mA·cm −2 , respectively. Moreover, the catalyst demonstrates outstanding stability, maintaining 200 h for HER operation, outperforming commercial Pt/C. This study highlights the advantage of dual active sites in boosting the intrinsic electrochemical activity and underscores the potential of Cu-doped perovskites for efficient hydrogen production. Graphical A Cu-doped La 0.5 Ba 0.5 CoO 3-δ perovskite (LBCC 0.2 ) was synthesized using a sol–gel method for alkaline hydrogen evolution reaction (HER). The resulting dual active sites, comprising Co species and oxygen vacancies, collectively enhance the electrical conductivity and accelerate HER kinetics of LBCC 0.2 . This leads to a low overpotential of 160 mV at a current density of 10 mA·cm −2 and an excellent stability over 200 h.