In-situ surface activation of polycrystalline LaNiO3 electrocatalyst for the oxygen evolution reaction

The efficiency of hydrogen production from water electrolysis is limited by the sluggish kinetics of the Oxygen Evolution Reaction (OER), necessitating catalytic material to avoid the high overpotentials. This study investigates LaNiO3 as a promising electrocatalyst for the OER in Alkaline Water Electrolysis selected for its cost-effectiveness and easy scale-up. LaNiO3, prepared by a co-precipitation method, shows good OER activity and electrochemical stability. Operando X-Ray Absorption Spectroscopy (XAS), reveals a crucial role of the Ni(II)/Ni(III) redox couple. Notably, a layer of a Ni(II) compound formed at the catalyst surface is oxidized under anodic potentials and possibly becomes the active sites for the adsorption of OH− and for the OER reaction. High resolution transmission electron microscopy confirms the formation of a defective outer layer during operation, indicating the presence of disordered structure on the surface of the electrocatalyst, which increases the number of active sites for the OER.