Constructing spin pathways in LaCoO3 by Mn substitution to promote oxygen evolution reaction

Abstract

Designing efficient oxygen evolution reaction (OER) electrocatalysts is essential for numerous sustainable energy conversion technologies. An obstacle that impedes the development of OER electrocatalysts is the insufficient emphasis on the spin attribution of electrons. Recently, the different spin configuration of reactants and products in the OER has been recognized as the factor that slows down the reaction kinetics. In this work, Mn substitution was introduced to LaCoO₃, which brought about lattice expansion and reduced crystalline field splitting energy. This led to the increase in the effective magnetic moment, which triggers the transfer of Co³⁺ from low to higher spin states. Thus, the hybridization of Co e_g and O 2p states across the Fermi level was strengthened. Specifically, with 25 at. % Mn substitution, LaCoO₃ transits from a semiconductor to a half-metal, which benefits the spin-oriented electronic transport and resultantly promotes the OER. This method paves the way for the construction of spin pathways in catalysts.