Abstract:

A carbon shell coating technique applicable to mesoporous catalysts was developed to address the issues of particle agglomeration and dissolution in platinum-based catalysts, and to enhance catalyst activity and durability through physical isolation. A selective carbon shell coating was applied to platinum nanoparticles anchored on the outer surface of mesoporous carbon catalysts. The effects of impregnation time, prepolymerization time, and dopamine concentration on the mesoporous catalyst pore structure and performance were systematically investigated. The results indicate that the sensitivity factors influence the catalyst structure and performance following the order: prepolymerization time, impregnation time, dopamine concentration. The optimal carbon shell coating parameters are determined as prepolymerization for 90 min, impregnation for 10 min, and dopamine concentration of 0.3 mg/mL. Under the condition, the obtained carbon shell coated catalyst exhibits a mesoporous structure retention rate of 95% and a carbon shell thickness of approximately 0.83 nm. The half-wave potential is increased by 46 mV compared to the pristine catalyst. After 30 000 cycles of accelerated degradation testing, the half-wave potential decays by only 5 mV, representing an 86% improvement in durability relative to the pristine catalyst.

Key words: proton exchange membrane (PEM) fuel cells, catalyst modification, carbon shell