In situ FT-IR studies of NO decomposition on Pt/TiO2 catalyst under UV irradiation

Photodecomposition of NO on the well-dispersed Pt/TiO2 catalyst under UV irradiation was studied by in situ DRIFT (Diffuse-Reflectance Infrared Fourier-Transform) spectroscopy. 2 wt% Pt/TiO2 catalyst was prepared by photochemical deposition method. The photocatalytic activity of Pt/TiO2 is highly dependent on its pretreatment. Although the catalyst exhibited a highly adsorption capability to NO after hydrogen reduction or thermal evacuation at 500°C, no evidence upon NO decomposition was observed under UV irradiation. While reducing the catalyst at 300°C in the hydrogen flow, it not only exhibited an intense NO adsorption but also conducted a direct decomposition of NO to N2 and O2 under UV irradiation. The hydrogen reduction at 200°C led to a weaker NO adsorption. During UV irradiation, the IR peaks of NO fully disappeared and N2O was formed. It is concluded that the photochemical prepared Pt/TiO2 catalyst after activating at mild reduction conditions is highly active for NO photodecomposition. The effective oxidation states of the active components, the surface structure and the reaction mechanisms will be discussed.