Defect Engineering for Enhanced Electrocatalytic Oxygen Reaction on Transition Metal Oxides: The Role of Metal Defects.

Metal defect engineering is a highly effective strategy for addressing the prevalent high overpotential issues associated with transition metal oxides functioning as dual-function commercial oxygen reduction reaction/ oxygen evolution reaction catalysts for increasing their activity and stability. However, the high formation energy of metal defects poses a challenge to the development of strategies to precisely control the selectivity during metal defect formation. We used density functional theory calculations to demonstrate that altering the pathway of metal defect formation released metal atoms as metal chlorides, which effectively reduced the formation energy of defects. The metal defects on the monometallic metal oxide surface (Mn, Fe, Co, and Ni) are selectively produced using chlorine plasma. The characterization and density functional theory calculations reveal that catalytic activity is enhanced owing to electronic delocalization induced by metal defects, which reduces the theoretical overpotential. Notably, ab initio molecular dynamics calculations, ex-situ XPS, and in-situ ATR-SEIRAS suggested that metal defects effectively improved the adsorption of reactive species on active sites and enhanced the efficiency of product desorption, thereby boosting catalytic performance. This article is protected by copyright. All rights reserved.