Engineering the CuO/MnO2 interface with multivalent conversion for low-temperature and efficient CO oxidation

Abstract

A novel interface of MnO2 with CuO with multivalent conversion is fabricated by the deposition-precipitation method for low-temperature and efficient CO oxidation. It is found that the temperature for CO thermal-catalytic oxidation to reach a complete conversion significantly decreases to 105 °C for the CuO/MnO2. A combination of experimental and theoretical studies demonstrates the successful formation of the CuO/MnO2 interface, inducing a pronounced effect that promotes CO oxidation. The CuO/MnO2 interface leads to the formation of Cu-O-Mn, a superior redox system with multivalent conversion (Cu+ + Mn4+ ↔ Cu2+ + Mn3+, Cu+ + Mn3+ ↔ Cu2+ + Mn2+), abundant active sites, excellent ability to activate O2, the rapid oxygen transfer, and more suitable adsorption energy for O2, CO, and CO2. These characteristics are advantageous to CuxO-MnxOy for achieving a 100 % removal of CO at a lower temperature. Furthermore, the computational study reveals that the CO oxidation process follows two mechanistic pathways (Eley-Rideal (E-R) and Mars-van Krevelen (M-K)), indicating that there is no competitive adsorption of CO and O2 on the CuO/MnO2. This study shows that the interface created between suitable metal oxides can improve the catalytic performance and provides new perspective for catalyst design and performance enhancement mechanisms.