Static and dynamic quantification tracking of asymmetric oxygen vacancies in copper-ceria catalysts with superior catalytic activity

Copper-ceria (Cu-Ce) catalysts with unique catalytic properties have high prospects as alternatives for noble metals in low-temperature catalytic oxidations. However, the quantitative description of the active sites in the redox processes still remains a challenge. Herein, a series of Cu-Ce catalysts were prepared by regulating the synthesis method, ARCu/Ce (atomic ratios of Cu to Ce), and pH of precipitation, so as to investigate CO and VOCs oxidations. Cu+-OV-Ce3+ configuration, as an asymmetric oxygen vacancy (ASOV), was formed in the copper-ceria interface. Its concentration was accurately regulated under varying pH, and was quantificationally identified by ex-situ techniques in static conditions. The maximum ASOV concentration was recorded for the CuCe3–11 catalyst, accounting for the best catalytic activity and stability. Moreover, the dynamic exchange behaviors (Cu+-OV-Ce3+↔ Cu2+-O2-(ad)-Ce4+) of the ASOV were quantificationally studied by in-situ techniques under the same reaction conditions. In the oxygen-containing reaction, 13% ASOV was first converted to Cu2+-O2-(ad)-Ce4+ species, and then wholly recovered in the presence of CO. In the CO oxidation processes, the dynamic exchange of ASOV maintained equilibrium under T50 and T100. This work offers future prospects for the quantification tracking of the active sites in catalysts, while also providing a universal strategy for the rational fabrication of high-performance environmental catalysts. [Display omitted] •Asymmetric oxygen vacancies (ASOV) were quantificationally studied in copper-ceria catalysts by multiple characterization techniques.•The influences of the method of synthesis, pH, and the atomic ratios of Cu to Ce on the concentration of ASOV were revealed.•The concentration of ASOV was effectively regulated via the adjustment of pH, ultimately giving the CuCe3-11 catalyst excellent catalytic performance.•The dynamic exchange (Cu+-OV-Ce3+↔Cu2+-O2--Ce4+) of ASOV was quantificationally traced for the first time.•100% CO and VOCs conversions were achieved at low-temperature conditions by base-metal oxides with facile synthesis methods.