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

Abstract

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 LaCuO3 perovskite oxide supported on inactive mesocellular siliceous foam (MCF), in which, the Cu species is featured by Cu3+. Then, LaCuO3-y/MCF with abundant Cu+ species was obtained by treating the as-prepared LaCuO3/MCF in H2/N2 flow. The catalytic activities of LaCuO3/MCF and LaCuO3-y/MCF were investigated for CO oxidation. The experimental results revealed that the Cu+ species rather than Cu3+ 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 O2, but also dramatically reduced the desorption energy of CO2 from defective surface, thereby enhancing the catalytic activity of CO oxidation over Cu+ notably.