Catalytic conversion of carbon dioxide to methane on ruthenium-cobalt bimetallic nanocatalysts and correlation between surface chemistry of catalysts under reaction conditions and catalytic performances

Catalytic conversion of CO ₂ to CH ₄ on cobalt oxide and Ru-doped cobalt oxide nanorods was studied with in-house ambient pressure X-ray photoelectron spectroscopy (AP-XPS) using monochromated Al Kα. A correlation between catalytic performances of the two catalysts and their surface chemistry under reaction conditions was built. Active phases of the two catalysts are metallic cobalt and bimetallic Co-Ru, respectively. Light-off temperature of Co-Ru catalyst is lower than that of a cobalt catalyst. Selectivity to production of CH ₄ and activity on the Ru-doped cobalt oxide are obviously enhanced by formation of bimetallic Co-Ru ultrathin film in its surface region in contrast to that of cobalt catalyst in the temperature range of 200-340 °C.