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

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 degrees 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 Au-0-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 Au-0. The high stability of the bifunctional Au-0-Au3+ sites is associated with the electronic interactions between gold and n-type semiconductor ZnO at their interface. (C) 2017 Elsevier Inc. All rights reserved.