Introducing ionic mediators to construct peak-splitting manganese oxide structures for efficient oxygen reduction reactions

Manganese oxides have received extensive attention in Oxygen Reduction Reaction(ORR) research. However, the poor electrical conductivity and oxygen adsorption capacity of manganese oxides limit their development, so it is necessary to prepare catalysts with highly active surfaces. We propose a method to introduce an ionically conductive medium and induce structural distortion via thermodynamics, resulting in novel peak-splitting highly active structures for enhanced oxygen reduction activity. With the aid of refined structural analysis, High-angle annular dark-field (HAADF-STEM) imaging, and theoretical calculations, it is elucidated that this peak-splitting structure results from thermodynamically induced structural distortions and atomic displacements. The introduction of the ionically conductive medium promotes the formation of Ag-O-Mn conductive bond bridges, which regulate the energy level matching of manganese oxides and oxygen intermediates. The thermodynamically induced structural distortion exposes new atomic planes in the material, and the creation of this highly active surface is accompanied by a redistribution of surface charges, which modulates the adsorption of manganese active sites with oxygen intermediates and greatly enhances the oxygen reduction activity. Specifically, this Ag-OMS-2 with a novel split structure exhibits excellent activity at 0.836 V, superior to Pt/C kinetics and good stability. The preparation of such highly active structures is instructive for the development of manganese oxides.