Unveiling the decisive role of surficial properties on CuOx/CeO2 catalysts during CO preferential oxidation

Abstract

The surficial properties of heterogeneous catalysts are vital in determining their catalytic performance. Herein, we take K-CuO_x/CeO₂ as a typical composite to unveil the decisive role of surficial properties on the adsorption strengths of reactants, configurations of intermediates and desorption of products during CO preferential oxidation. Results show that adding K initially has minimal effect, but too much drastically reduces catalytic performance. Detailed analyses indicate adding K to CuO_x/CeO₂ catalyst increases the surficial basic sites, which not only inhibits O₂ activation and CO₂ desorption, but also reduces surface defects, Cu⁺ species and hydroxy species. Such a vast difference in adsorption behavior and surface species in turn lead to the transformation of intermediates from carboxylates to carbonates. DFT calculations further reveal that the barrier of rate-determining step for CuO_x/CeO₂ catalyst in carboxyl path is lower than that of K-CuO_x/CeO₂ in carbonate path, thus rendering a higher catalytic activity of CuO_x/CeO₂.