Characterization of Au/MnO x /TiO2 for Photocatalytic Oxidation of Carbon Monoxide

摘要

The Au/MnO x /TiO2 catalyst was used for the photocatalytic oxidation of carbon monoxide. The catalytic activity of Au/MnO x /TiO2 with low concentration of manganese (3–7 mol%) was much higher than that of Au/TiO2. The surface of Au/MnO x /TiO2 was characterized by XPS and Raman spectroscopy. While the main state of manganese in 13.8 mol% MnO x /TiO2 was Mn4+ species, Mn3+ was the dominant species in the samples with below 6.5 mol% manganese. Raman spectroscopy revealed that the interaction between the MnO x and TiO2 form Mn–O–Ti species in which the state of manganese was Mn3+. The Au particles also interacted with both MnO x and TiO2 to modify the surface of them. In the case of the Au species, low loading of manganese produced the metallic Au0 and perimeter interfacial Auδ+, whereas high loading showed the coexistence of three components which were metallic Au0, perimeter interfacial Auδ+, and oxidic Au3+. The catalytic active component was the metallic Au0 and perimeter interfacial Auδ+ species, which were dispersed on TiO2 and Mn3+/TiO2.