A theoretical study of the improved CO oxidation on WC supported Au monolayer by Cu doping

Abstract

Abstract Metal monolayer supported on tungsten carbides have received considerable attention in the field of catalysis, while the adsorption properties of reactants need to be optimized to improve the catalytic activity further. Alloy monolayers on tungsten carbides can deliver different geometric and electronic characters from pure metal layers, owing to the change in local environments. Herein, using the first-principles calculations, the CO oxidation processes on the supported CuAu alloy monolayer on tungsten carbide are systematically investigated and compared with that on pure metal monolayers. It is found that introducing Cu dopant in Au monolayer will elevate the d-band center of the formed alloy monolayer and thus enhancing the adsorption of reactants around the Cu atom, which is caused by the charge redistribution. Especially, the unbalanced interaction strength between Cu-O and Au-O promotes the rotation and migration of oxygen atom to interact with the C atom of CO, which lowers the energy barriers for the formation and dissociation of OOCO intermediate. The oxidation of CO by an atomic O with the largest energy barrier of 0.27 eV along the Langmuir-Hinshelwood pathway is identified as the rate determining step, which is superior or comparable to the reported CO oxidation catalysts. The significance of alloy monolayer on tungsten carbides are further highlighted by comparing the adsorption energy and reaction barrier of rate-limiting step on the pure metal monolayers. This work is insightful for the rational design of highly efficient catalysts based on alloy systems.