Enhanced CO oxidation performance over hierarchical flower-like Co3O4 based nanosheets via optimizing oxygen activation and CO chemisorption

Enhancing low-temperature activity is a focus for carbon monoxide (CO) elimination by catalytic oxidation. In this work, the hierarchical flower-like silver (Ag) modified cobalt oxides (Co 3 O 4 ) nanosheets were prepared by solvothermal method and applied into catalytic CO oxidation. The doped Ag species in the form of AgCoO 2 induced the prolongated surface Co–O bond and weaker bond intensity. Consequently, the oxygen activation/migration ability and redox capacity of Ag 0.02 Co were enhanced with more oxygen vacancies. The chemisorbed CO was preferentially converted to CO 2 but not carbonates. The inhibited carbonates accumulation could avoid the coverage of active sites. According to Density functional theory (DFT) calculations, the electron transfer from AgCoO 2 to Co 3 O 4 promote electron donation ability of Co 3 O 4 layer, benefiting for oxygen activation. Moreover, the longer Co–C and C–O bond length suggest the weakened chemisorption strength and higher active of CO molecule. The Ag modified Co 3 O 4 exhibited more satisfactory activity at lower temperature. Typically, it realized 100% CO conversion at 90 °C, and displayed 6.3-fold higher reaction rate than pristine Co 3 O 4 at 40 °C. Moreover, the Ag 0.02 Co exhibited outstanding long-term stability and water resistance. In summary, the optimized oxygen activation, CO chemisorption and interfacial electron transfer synergistically boosted the CO oxidation activity on Ag modified Co 3 O 4 .