CO oxidation over gold catalysts supported on CuO/Cu2O both in O2-rich and H2-rich streams: Necessity of copper oxide

In order to clarify the nature of cooperation effect of gold–copper in CO oxidation without disturb of substrate materials, in this work we prepared nano-sized copper and cuprous oxide with different morphologies followed by the deposition of gold nanoparticles. The reaction of CO oxidation under both hydrogen-rich and oxygen-rich streams was investigated over as-prepared CuO/Cu2O materials and the corresponding supported gold catalysts. The characterizations reveal that in the unreduced Au/Cu2O samples, Au+–Cu2+ assembles are dominant on the surface of Cu2O substrate due to the spontaneous oxidation–reduction reaction of Au3+ and Cu+, while both of Au3+-Cu2+ and Au+-Cu2+ entireties are existed in the unreduced Au/CuO sample and the former is dominant. A comprehensive analysis of the catalytic results over these samples for CO oxidation in both oxygen-rich and hydrogen-rich streams demonstrates that the CuO species (not Cu2O) play a more critical role for the oxidation of CO and the improved catalytic activity of the Au/CuO catalyst can be attributed to the strong interactions of CuO support with nanogold particles.