Boosting the electrocatalytic activity of LaCoO3 core–shell hollow spheres for oxygen evolution reaction through modulating inner oxygen vacancies†

Abstract

Due to the limited active surface area of perovskite oxides, improving their electrocatalytic performance faces many challenges. To solve this problem, defect engineering and hollow nanostructures have become effective strategies. Therefore, there is an urgent need to develop an efficient synthesis method to prepare LaCoO₃ catalysts containing both oxygen vacancies (V_o) and hollow nanostructures. In this study, we successfully synthesized LaCoO_3−x core–shell hollow spheres with V_o modification by a solvothermal method which were subsequently heat treated in Ar/H₂ atmosphere. It is worth mentioning that by adjusting the calcination time, we can effectively control the degree of V_o. In particular, the high concentration of V_o in LaCoO₃ and its unique core–shell hollow structure not only promote the adsorption of water, but also accelerate the transfer of charge, thus giving it excellent electrocatalytic properties. This is demonstrated by the remarkable electrocatalytic activity of LaCoO_3−x core–shell spheres for the oxygen evolution reaction (OER) in alkaline solutions with an overpotential of 394 mV and a Tafel slope of 89.1 mV at a current density of 10 mA cm⁻² dec⁻¹.