Mechanistic Insights into Proximity Effect-Mediated Oxygen Reduction Reaction Performance Regulation by Platinum...

Fuel cells are a promising energy conversion technology, yet deficiency activity/selectivity/stability of catalyst in cathodic oxygen reduction reaction (ORR) has delayed its commercialization. Carbon supported Pt-based catalysts, though recognized as the most efficient for achieving 4-electron O₂ reduction to H₂O and maximizing conversion efficiency, are limited by Pt's scarcity and high cost. Controlling Pt loading is a viable approach to reduce costs and enhance ORR performance, but this alters catalyst physical properties. While Pt morphology and size effects on ORR are well-studied, the influence of Pt nanoparticle proximity effect remains underexplored. This article aims to provide a comprehensive insight into the mechanisms by which proximity effect of Pt nanoparticles affects ORR activity/selectivity/stability. First, ORR mechanism of Pt-based catalysts is described, which provides theoretical guidance for designing more efficient catalysts. Then, with combining the experimental and theoretical results, revisiting the impact of proximity effect of Pt particles on reaction pathways of oxygen reduction and degradation mechanisms of Pt nanoparticles, to reveal how ORR activity/selectivity/stability are affected by proximity effect. Finally, focusing on the main challenges and possible solutions under these reaction mechanisms. This article highlights that regulating particle proximity effect plays a pivotal role in promoting electrocatalytic performance of supported catalysts.