Gold nanoparticles deposited on manganese(III) oxide as novel efficient catalyst for low temperature CO oxidation

Abstract

Nanostructured α-Mn 2O 3 materials have been employed as supports for anchoring gold nanoparticles, which exhibited high activities for low-temperature CO oxidation in the absence or presence of excess H 2. The specific activity was found to increase with gold loading up to 5 wt%. Comparing the specific rates for CO oxidation (ca. 1.50 mmol CO g −1 Au s −1 at 25 °C) with the highly active Au catalysts in the current literature confirmed the exceptionally high activity of these new materials. The rate of CO oxidation showed about half-order dependence of CO partial pressure and was nearly independent of O 2 concentration. X-ray photoelectron spectroscopy combined with in situ CO adsorption studies revealed the presence of both metallic and positively charged gold species in the catalyst under reaction conditions. As compared with the coprecipitation-derived Au–MnO x catalyst, the superior activities of Au/ α-Mn 2O 3 have been attributed to its unique redox properties and the facile formation of activated oxygen species on the surface.