Ligand effect of SnO2 on a Pt–Ru catalyst and the relationship between bond strength and CO tolerance

Pt–Ru/SnO2/C catalysts were prepared by a rapid quenching method. The structure and morphology of Pt–Ru particles in Pt–Ru/SnO2/C are controlled to obtain the same Pt–Ru particle as that in a commercial Pt–Ru catalyst. The Pt–Ru/SnO2/C and commercial Pt–Ru catalysts were characterized by X-ray diffraction and scanning transmission electron microscopy. Electrochemical activities were evaluated by CO stripping voltammetry, single cell tests, in situ infrared reflection–absorption spectroscopy (IRRAS) and surface-enhanced infrared absorption spectroscopy (SEIRAS). The Pt–Ru/SnO2/C catalyst showed the same structure, morphology and catalytic activity for hydrogen oxidation reaction (HOR) in the absence of CO as those of a Pt–Ru/C catalyst. Both the activity for electrochemical CO oxidation and Pt–CO bond strength were quantitatively evaluated. The addition of SnO2 decreased the Pt–CO bond strength with maintained HOR activity to enhance CO tolerance.