Unravelling the real active center for CO oxidation-Cu+ or Cu3+: A case of model LaCuO3/MCF

• LaCuO 3 /MCF featured by Cu 3+ was prepared by hydrothermal deposition strategy. • LaCuO 3-y /MCF with abundant Cu + species was obtained by reducing LaCuO 3 /MCF in H 2 /N 2 flow. • The real active center for CO oxidation was probed by experimental and DFT calculations. • The Cu + species rather than Cu 3+ was the reactive site for CO oxidation. • The Cu + species facilitated adsorption of CO and O 2 and reduced desorption energy of CO 2 . Cu-based catalysts are one of the promising alternatives for industrial carbon monoxide (CO) oxidation applications. However, the exact active sites as well as their natures for CO oxidation have been still not fully understood yet. Herein, we designed and constructed a nano-size LaCuO 3 perovskite oxide supported on inactive mesocellular siliceous foam (MCF), in which, the Cu species is featured by Cu 3+ . Then, LaCuO 3-y /MCF with abundant Cu + species was obtained by treating the as-prepared LaCuO 3 /MCF in H 2 /N 2 flow. The catalytic activities of LaCuO 3 /MCF and LaCuO 3-y /MCF were investigated for CO oxidation. The experimental results revealed that the Cu + species rather than Cu 3+ was the reactive site for CO oxidation. Moreover, density functional theory (DFT) calculations uncovered that the Cu + species not only considerably facilitated the adsorption of CO and O 2 , but also dramatically reduced the desorption energy of CO 2 from defective surface, thereby enhancing the catalytic activity of CO oxidation over Cu + notably.