Supported Metal Centers in Oxygen Electrocatalysis

Oxygen electrocatalysis, which typically involves oxygen evolution/reduction reactions (OER/ORR), plays a pivotal role in sustainable energy technologies such as fuel cells, metal-air batteries, and water/seawater electrolyzers. Nevertheless, the practical implementation of these devices faces formidable challenges stemming from their high kinetic barriers and heavy reliance on precious metal-based catalysts. Supported metal site configurations, particularly for single-atom catalysts, offer a promising avenue for enhancing the catalytic activity while minimizing precious metal consumption. Although their performance enhancement is frequently ascribed to "strong metal-support interactions" (SMSI), the blanket use of this term beyond its classic definition obscures various distinct mechanisms and prevents the establishment of clear structure-activity relationships. This review comprehensively examines supported metal active centers for oxygen electrocatalysis and systematically considers their structural characteristics, synthesis methodologies, promotion strategies, and catalytic properties. Moving beyond the limitations of the SMSI concept, the design rationales and mechanisms underlying the effect of the support on the active metal center are analyzed. Furthermore, recent advancements in the application of these catalysts in energy devices, including water/seawater electrolyzers, fuel cells, and metal-air batteries, are thoroughly summarized. Finally, persistent challenges and future perspectives for advancement toward highly efficient supported metal centers for oxygen electrocatalysis are outlined.