Surface Engineering of Perovskite Oxide LaCo_0.67Cu_0.33O₃ for Improved Overall Water Splitting Activity

Perovskite oxides continue demonstrating suboptimal electrocatalytic performance for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) due to their inherently low activity, inadequate electronic conductivity, and restricted availability of active sites. Defect engineering has attracted significant attention as a promising approach to enhancing reaction kinetics. In this study, a LaCo_0.67Cu_0.33O₃ (LCCO) composite perovskite electrocatalyst was synthesized using a sol-gel method followed by acid etching for defect engineering (LCCO-x, where x = 6, 12, 24, and 30, indicating the treatment time in hours). Particularly, LCCO-24 exhibited high activity and improved reaction kinetics for both the OER and HER under alkaline conditions. When employed for overall water splitting, it achieved a low full-cell voltage of 1.49 V at a current density of 10 mA·cm^-2, comparable to leading noble metal catalysts. Analysis confirmed that the enhancement in bifunctional electrocatalytic activity was attributed to the increased presence of oxygen defects and the increase in surface area. This study demonstrates that defect engineering is an effective approach for investigating perovskite oxides in the context of electrochemical water splitting.