Experimental and Theoretical Study on SO 2 Tolerance of Pt Electrocatalysts: Role of Carbon Support

Durability of fuel cell is still a major concern for successful progress and commercialization of proton exchange membrane fuel cell (PEMFC) technology. One of the factors affecting durability of PEMFC is the impurities present in atmospheric air that is fed at cathode which degrades the PEMFC performance. Conventionally used electrocatalyst, platinum (Pt) supported on carbon (C), is susceptible even to trace amounts of SO 2 present in atmospheric air. The present study investigates the effect of SO 2 and role of carbon support in platinum electrocatalysts at different weight ratios of carbon and platinum (20 wt% and 40 wt% Pt/C). Tolerance towards SO 2 contaminations has been evaluated through electrochemical studies. The sulfur coverage percentage was found to be 57 % and 43 % for 20 wt% and 40 wt% Pt/C, respectively. However, the unsupported Pt black showed better tolerance with 31 % of sulfur coverage implying the susceptibility of carbon towards SO 2 contamination. Density functional theory (DFT) studies proved the synergistic effect of SO 2 adsorption and its dissolution mechanism on carbon supported Pt electrocatalysts.