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

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, LaCuO_3-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 LaCuO_3-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.