Poisoning Effects of H2S, CS2, and COS on Hydrogen Oxidation Reaction over Pt/C Catalysts

Hydrogen used in proton exchange membrane fuel cells (PEMFCs) mainly originates from refinery resources in which inevitable S-containing impurities possibly reduce the fuel cell life. Herein, the poisonous influence of trace impurities of H2S, carbon disulfide (CS2), and carbonyl sulfide (COS) on the performance of Pt/C catalysts in hydrogen oxidation reaction (HOR) is investigated by a combination of electrochemical measurements, structural characterization, and DFT calculations. Rotating disk electrode (RDE) half-cell electrochemical experiments were used to determine the impact of H2S, CS2, and COS on the HOR activity and the recovery capability of a commercial Pt/C catalyst. The experimental results indicate that CS2 even poses a more severe threat to the HOR activity than H2S, while COS poses a weaker threat than H2S. Moreover, all of H2S, CS2, and COS have a deteriorative impact on the regeneration of Pt/C catalysts. The theoretical calculation results reveal that CS2 and COS can decrease the activity of HOR by decreasing the d-band center of Pt atoms except for occupying the active sites of Pt, while H2S deactivates the catalyst solely by occupying the active sites. Based on the analysis, the presence of trace CS2 and COS, as well as H2S, will result in the serious degeneration of the Pt/C catalysts. These results provide insights into the deactivation mechanism of Pt-based catalysts and are significant for the practical applications of PEMFCs.