Optimizing Pt catalyst performance for oxygen reduction reaction via surface functionalization of Vulcan XC-72R carbon black support

Abstract In this study, the impact of Vulcan XC-72R carbon black support pre-treatment on the oxygen reduction reaction performance of the Pt catalyst was investigated. Catalysts were synthesized via the polyol method using ethylene glycol, with different pre-treatment pathways (with H2O2 and HNO3 solutions) applied to the carbon black for surface functionalization. Additional samples using non-treated XC-72R and N-doped XC-72R were prepared for comparison, alongside a commercial Pt/C catalyst. Electrochemical characterization revealed that H2O2 pre-treatment resulted in the largest electrochemically active surface area and enhanced oxygen reduction reaction activity, surpassing both non-treated and commercial catalysts. The H2O2-treated catalyst exhibited superior stability during accelerated stress testing. SEM and XRD analyses confirmed the presence of Pt nanoparticles with sizes between 2.93-4.46 nm (that are considered optimal) for the H2O2-treated sample. Raman spectroscopy indicated that H2O2 pre-treatment led to a less ordered carbon structure with more defects, which is favorable for improved Pt utilization. It was concluded that H2O2 pre-treatment of XC-72R significantly improves the catalytic activity of the Pt catalyst, demonstrating the potential for optimizing Pt loading while maintaining desired ORR kinetics in fuel cell applications.