Engineering cation vacancy defects on LaNiO3 for efficient oxygen evolution reaction

Abstract

Perovskite oxides (ABO₃) have been extensively studied as electrocatalysts for the oxygen evolution reaction (OER) due to their highly tunable and flexible electronic structures. However, their practical use as electrocatalysts has been hindered by limitations such as less surface area and low electrical conductivity. In this work LaNiO₃ (LNO) perovskite oxides were synthesized and modified by selectively removing A-site cations by etching with dilute acetic acid treatment. This acid etching process induced cation and oxygen vacancies, resulting in an increased surface area, and enhanced surface wettability, facilitating improved interaction with water molecules thereby promoting a higher density of catalytically active sites. These structural and surface modifications led to superior OER performance in alkaline media. The optimized catalyst, LNO-3M, demonstrated a reduced overpotential, smaller Tafel slope, higher turnover frequency, and greater mass activity compared to pristine LNO. Electrochemical measurements confirmed faster charge transfer and a higher density of active sites due to the increased electrochemical surface area. Furthermore, LNO-3M maintained excellent operational stability over extended periods. This study underscores the efficacy of a simple acid etching strategy to enhance the catalytic activity of LaNiO₃ for efficient water splitting applications.