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CO oxidation at mild condition is significant for industrial process but still challenging nowadays, especially for the non-noble metal catalysts. The preparation method significant affect the catalytic activity of the catalyst. Comparing with cobalt supported on tantalum oxide prepared by impregnation method, Co/Ta2O5 prepared by deposition–precipitation method with urea in this study has smaller particle size, higher specific surface area and better redox properties, and these features make the catalyst exhibit higher catalytic activity for CO oxidation at mild condition. 90% CO conversion was achieved at 130 ℃, and CO was fully converted at 150 ℃. The XPS and DRIFTs results show that Co/Ta2O5 has more oxygen vacancies, and the absorbed CO will react with oxygen. The study may provide a new thought for the preparation of catalysts with high activity at mild condition. [ABSTRACT FROM AUTHOR]

• Ta 2 O 5 with rich oxygen vacancies was synthesized by hydrothermal method. • Co 3 O 4 anchored in oxygen vacancies formed highly dispersion Co 3 O 4 /Ta 2 O 5. • Co 3 O 4 /Ta 2 O 5 exhibited the good CO conversion, and the temperature of 90% CO conversion was approximately 150 ℃ at the high space velocity of 156,000 h-1. To solve the problem of uneven dispersion of catalysts, Ta 2 O 5 with oxygen vacancy was introduced for CO conversion. In this work, cobalt was anchored in oxygen vacancies of Ta 2 O 5 to form highly dispersion Co 3 O 4 /Ta 2 O 5. The characteristics results of XRD, SEM, BET, TGA, ESR and H 2 -TPR show that cobalt was anchored in oxygen vacancies forming high dispersion Co 3 O 4 /Ta 2 O 5 and a strong interaction between Co 3 O 4 and Ta 2 O 5. The CO conversion was tested at 150 ℃ and resulted in a 90% conversion rate, which is significantly higher than that of pure Co 3 O 4 and Ta 2 O 5. The main mechanism of Co 3 O 4 /Ta 2 O 5 contributed to CO conversion was investigated by XPS and In-situ DRIFTs, revealing that Co3+ and activated oxygen play a vital role in CO conversion. [Display omitted] [ABSTRACT FROM AUTHOR]