Structurally Tunable Graphitized Mesoporous Carbon for Enhancing the Accessibility and Durability of Cathode Pt-Based...

Low Pt utilization and intense carbon corrosion of cathode catalysts is a crucial issue for high-efficiency proton exchange membrane fuel cells due to the highly demanded long-term durability and less acquisition/application cost. Herein, structurally tunable graphitized mesoporous carbon (GMC) is obtained by direct high-temperature pyrolysis and in situ-controlled mesopore formation; the structure-optimized GMC1300-1800 exhibits a mesopore size of 7.54 nm and enhanced corrosion resistance. Functionalized GMC1300-1800 is loaded with small-sized Pt nanoparticles (NPs) (1.5 nm) uniformly by impregnation method to obtain Pt/GMC1300-1800 and form an "internal platinum structure" to avoid sulfonic acid groups poisoning as well as ensure O₂/proton accessibility. Hence, the electrochemically active surface area (ECSA) of Pt/GMC1300-1800 reaches 106.1 m² g^-1 _Pt, while mass activity and specific activity at 0.9 V are 2.1 and 1.4 times those of commercial Pt/C, respectively. Notably, the ECSA decay is less than 17% for both 30 000 cycles' accelerated durability tests (ADTs) of Pt attenuation and carbon attenuation. Accordingly, the optimized mesoporous structure of GMC1300-1800 significantly decreases the coverage of sulfonic acid groups on Pt NPs, leading to the highest peak power density in the single-cell test. Density functional theory calculations demonstrate the synergistic effect between graphitization and mesoporosity on enhancing the accessibility and durability of the catalysts.