Surface-engineered manganese oxide via sodium borohydride for optimized ORR active electrocatalyst

Abstract

Manganese oxide octahedral molecular sieves (OMS) have garnered attention as promising electrocatalysts for oxygen reduction reactions (ORRs) due to their cost-effectiveness as well as durability. However, their practical application is limited by inherent drawbacks such as low electrical conductivity and insufficient intrinsic catalytic activity. To overcome these challenges, we employed a surface reduction etching treatment using NaBH4 to optimize the oxygen vacancy of OMS. The treatment with a 6 mmol/L NaBH4 solution significantly increased the number of oxygen vacancies on the surface of OMS, which serve as crucial active sites facilitating the adsorption and dissociation of oxygen molecules, thereby enhancing ORR activity. Furthermore, the treatment effectively regulated the Mn3+/Mn4+ ratio on the nanosphere surface, further promoting catalytic efficiency by facilitating the transfer of electrons during the ORR process. Notably, the optimized OMS material exhibited a remarkable half-wave potential of 0.661 V, highlighting its improved performance and potential as a suitable replacement for traditional platinum-based catalysts. This straightforward and scalable method unlocks the potential of OMS materials for practical applications, offering a promising solution for energy storage as well as conversion technologies that require efficient ORR catalysts.