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

The surficial properties of heterogeneous catalysts are vital in determining their catalytic performance. Herein, we take K-CuOx/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 CuOx/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 ratedetermining step for CuOx/CeO2 catalyst in carboxyl path is lower than that of K-CuOx/CeO2 in carbonate path, thus rendering a higher catalytic activity of CuOx/CeO2.