Tailoring Au-CuO interfaces for enhanced activity in CO oxidation

Abstract

Tailoring metal-oxide interfaces with controllable structures are challenging due to the complexity of interfacial structures involving multiple influence factors. Herein, both Au-CuO/Cu2O catalysts with different Au-CuO interfaces tuned by altering original Cu2O morphologies were prepared via a colloid-deposition method followed by restructuring in 1 %CO/Air atmosphere at 240 °C. Strong morphology dependence on original Cu2O nanocrystals was observed. The Au-CuO interactions over Au-CuO/c-Cu2O (cubes) catalyst are stronger than those over Au-CuO/o-Cu2O (octahedra), resulting in less electron-rich Au species formed. Catalytic performance of different Au-CuO interfaces in CO oxidation follows an order of Au-CuO/c-Cu2O > Au-CuO/o-Cu2O. Kinetic results together with in situ DRIFTS spectra demonstrate that a Langmuir-Hinshelwood (LH) mechanism was proceeded over Au-CuO/c-Cu2O catalyst, whose excellent activity could arise from the fleet desorption of adsorbed surface carbonate species to produce CO2, while Au-CuO/o-Cu2O catalyzing CO oxidation was involved with both LH and Mars-van-Krevelen mechanisms. These results greatly deepen the fundamental understanding of Au-CuO interfacial catalysis in CO oxidation and broaden the concept of morphology engineering strategy in developing efficient heterogeneous catalysts.