Low-temperature CO oxidation on Co(0001)

Highlights: • Low-temperature oxidation of CO, perhaps the most extensively studied reaction in the history of heterogeneous catalysis, is becoming increasingly important in the context of cleaning air and lowering automotive emissions. • However, the elementary processes of low temperature CO oxidation on Co-based photocatalysts still remain unclear. • Our results demonstrate that low temperature oxidation of CO occurs efficiently on the Co₃O₄-like oxide surface at 90 K, leading to the formation of CO₂. • Whereas, the formation of carbonate species via the CO₂ product and weakly bound oxygen species will reduce the yield of low temperature CO₂. • Thus, how to block the formation of carbonate plays a key role in enhancing the low-temperature CO₂ production on the Co₃O₄-like oxide surfaces. • We believe this is a very important result that will generate tremendous interests in the scientific community, and will very likely push the field of fundamental study of low temperature CO oxidation a significant step forward. Low-temperature oxidation of CO, perhaps the most extensively studied reaction in the history of heterogeneous catalysis, is becoming increasingly important in the context of cleaning air and lowering automotive emissions. Here, we have studied low-temperature CO oxidation on Co(0 0 0 1) using temperature programed desorption method. We show that chemisorbed O adlayer on Co(0 0 0 1) does not promote CO₂ formation. However, when a Co₃O₄-like surface is formed at 90 K, large amount of CO₂ is produced at 90 K in the presence of weakly bound oxygen species, demonstrating that low-temperature CO oxidation can be rationalized on O₂-saturated Co₃O₄-like oxide surfaces. However, the formation of carbonate species via the CO₂ product and weakly bound oxygen species reduces the yield of low temperature CO₂. Thus, how to block the formation of carbonate plays a key role in enhancing the low-temperature CO₂ production on the Co₃O₄-like oxide surfaces.