The effects of Bi2O3 on the CO oxidation over Co3O4

The Co3O4 and Bi2O3–Co3O4 were prepared by precipitation and co-precipitation method. The samples were characterized by XRD, BET, H2-TPR, Raman, XPS and EPR. The low-temperature CO oxidation on the catalysts was also investigated. The results showed the deposition of Bi2O3 enhanced the activity and stability of Co3O4 for CO oxidation. 20 wt.% Bi2O3–Co3O4 could completely convert CO as low as −89 °C, and maintain the complete oxidation of CO at −75 °C for 10 h. XRD and Raman results showed Bi2O3 could enter the lattice of Co3O4, and promote the formation of the lattice distortion and structural defect. H2-TPR results showed that reduction of Co3O4 was promoted and the diffusion of oxygen was accelerated. XPS and EPR results showed the surface richness of Co3+ and the increase of Co2+ in 20 wt.% Bi2O3–Co3O4. The formation of more Co2+ in 20 wt.% Bi2O3–Co3O4 could produce structure defects and lead to the formation of more oxygen vacancy, which was suggested to play the critical role in promoting the catalytic activity and stability of 20 wt.% Bi2O3–Co3O4.

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► The deposition of Bi2O3 enhances the activity and stability of Co3O4 for CO oxidation.
► 20 wt.% Bi2O3–Co3O4 can completely convert CO as low as −89 °C.
► Bi2O3 promotes the formation of the lattice distortion and structural defect.
► Oxygen vacancy plays the critical role in CO oxidation on 20 wt.% Bi2O3–Co3O4.