Au0–Au3+ bifunctional site mediated enhanced catalytic activity of Au/ZnO composite in diesel particulate matter oxidation

Abstract

Hydrogen-reduced air-calcined 1%Au/ZnO composite synthesized by gold impregnation in ZnO has been utilized as catalyst for diesel particulate matter (DPM) oxidation. The catalyst was characterized by UV-vis optical absorption, X-ray photoelectron spectroscopy and transmission electronic microscopy. The composite catalyst showed excellent activity for the oxidation of DPM at temperature as low as 230°C. The activity of the catalyst does not change up to 6 oxidation cycles. The high catalytic activity of the composite has been attributed to the formation of stable Au0–Au3+ bifunctional catalytic sites at the gold-ZnO interface, which enhances the contact efficiency of solid particulate matter on Au3+ and the generation of superoxide species on Au0. The high stability of the bifunctional Au0-Au3+ sites is associated with the electronic interactions between gold and n-type semiconductor ZnO at their interface.