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.