An Operando Study of H2O-Enhanced Low-Temperature CO Oxidation on Pt(111) under Near Ambient Pressure Conditions

Fundamental studies of catalytic reaction mecha-nisms of working catalysts are of great interest and importance. Herein we report an operando study of moisture effect on low-temperature CO oxidation on Pt(111) under near ambient pressure conditions using a flow mode reactor equipped with a polarization-modulation infrared reflection absorption spectrosco-py and online mass spectroscopy to monitor surface species and reaction rates, respectively. The moisture was observed to enhance the CO oxidation rate on Pt(111) between 290 and 320 K, and the enhancement effect varies with reaction temperature. Character-ization results of Pt(111) surface after CO oxidation reactions suggest reversibly adsorbed OH species and irreversibly adsorbed COOH species resulting from water activation on Pt(111) at temperatures around 300 K as the key surface intermediates. These results provide experimental evidence for water-enhanced low-temperature CO oxidation on Pt(111) under near ambient pressure conditions.