Chemical interaction between Pt and SnO2 and influence on adsorptive properties of carbon monoxide

The adsorption and catalytic properties of Pt/SnO2 were investigated as a model catalyst system that undergoes strong chemical interaction upon reduction–oxidation treatment. The surface platinum on Pt/SnO2 adsorbed very little CO at room temperature after reduction with hydrogen at 400 °C. This chemical interaction was found to be related with the reaction between precious metal and reduced tin oxide support. The Pt/SnO2 particles after reduction treatment were composed of a core/shell structure where the core of Pt was covered with an oxide shell. An X-ray diffraction pattern of Pt/SnO2 sample after reduction at 400 °C contained some lines attributed to intermetallic compounds, such as PtSn2 and PtSn4. The Pt/SnO2 catalyst was employed for a fuel electrode of a polymer electrolyte fuel cell and compared with the conventional Pt/C catalyst. Both catalysts were degraded with the presence of CO in hydrogen. However, the degradation of Pt/SnO2 with 100 ppm CO was insignificant as compared with that of Pt/C.