Enhancing Durability of Pt Catalysts in the Oxygen Reduction Reaction by Confinement Effect of Mesoporous Carbon

Platinum-carbon (Pt/C) catalyst is one of the most promising cathode materials for proton exchange membrane fuel cells (PEMFCs). However, it faces significant durability challenges, primarily due to growth and agglomeration of platinum nanoparticles (Pt NPs), which results in increased Pt particle size and consequent loss of catalytic activity. In this study, an internally pearl-like mesoporous carbon (IPMC) support with beaded pore channels was constructed to investigate the deposition sites of Pt NPs within carbon supports. Through precisely confining Pt NPs within the pore channels by leveraging the unique pore architecture, efficient confinement and stabilization of Pt NPs were achieved. Average size of Pt NPs in IPMC increased by only 0.46 nm after 30000 cycles of accelerated durability test (ADT), significantly less than the growth (0.79 nm) observed in conventional solid carbon-supported catalysts. The IPMC-based catalyst also exhibited slower electrochemical performance decay. The electrochemical active area (ECSA) loss rate of the mesoporous carbon catalyst was 24.18%, significantly lower than 32.33% observed for solid carbon catalyst in comparative testing. This superior durability originates from unique pore structure of IPMC, which imposes spatial confinement effects that effectively suppress Ostwald ripening and migration of Pt NPs, thereby mitigating the degradation of oxygen reduction reaction (ORR) activity. This work delivers a precise structural blueprint for optimal carbon carriers of high-stability PEMFCs catalysts by revealing how beaded mesopores confine Pt NPs: interconnected pore channels with local constrictions form spatial barriers which hinder dissolved platinum species diffusion while anchoring particles.