Ultralow doping of Zr species into Co3O4 catalyst enhance the CO oxidation performance

The oxidation of carbon monoxide (CO) has garnered significant interest for its application in treating automobile exhaust. In this study, we employed the sol-gel method to synthesize a series of cobalt -zirconium oxide catalysts with various Co/Zr ratios, aiming to catalyze the oxidation of CO effectively. The findings showed that the Co 90 Zr 10 catalyst, with a cobalt -to -zirconium ratio of 90:10, not only exhibited exceptional catalytic efficiency, achieving a 90 % conversion of CO at 94 degrees C, but also sustained superior thermal stability and resistance to water. The presence of both cobalt defects and oxygen vacancies significantly enhances the catalytic activity, which is attributed to the doping of zirconium. The characterization analyses indicated the incorporation of zirconium into the Co 3 O 4 spinel lattice modifies the valence states (Co 3+ /Co 2+ ) and geometries (Co Oh /Co Td ) of the cobalt cations. This alteration results from a variety of partial electron transfers and substitution sites. Enhanced ratios of Co 3+ /Co 2+ and Co Oh /Co Td in the Co x Zr y catalysts lead to improved reducibility and oxygen mobility. Consequently, this facilitates the lower -temperature oxidation of intermediates during the catalytic conversion of CO. DFT result showed that the Co 3 O 4 after Zr doped has lower adsorption energy and revealed the reaction mechanism of CO catalytic oxidation.