One-Step Hydrothermal Synthesis of Pd-Modified TiO2with High Photocatalytic Activity for Nitric Oxide Oxidation in Gas Phase

Abstract

Palladium-modified titanium dioxide, prepared using a one-step hydrothermal synthesis method, was employed for the photocatalytic oxidation of nitric oxide in gas phase. It was found that palladium dopants in the prepared photocatalysts existed as Pd2+ ions, palladium oxide particles, and metallic triphenylphosphine palladium. Pd2+ ions provided key contributions to the improvement of photocatalytic activity, while triphenylphosphine palladium and palladium oxide deposits on titanium oxide had almost no positive effect on nitric oxide oxidation. Results of the study indicated that photogenerated electrons and holes were efficiently separated after palladium doping. The bimodal pore-size distribution of the catalysts enhanced the speed of the photocatalytic reaction. Activity tests showed that the optimum palladium dopant content was 0.05% and the maximum conversion of nitric oxide was about 72.6% higher than that using titanium dioxide powder at 100 ppm. Results of this study show that palladium/titanium dioxide prepared using the one-step hydrothermal method may be more efficient in oxidizing nitric oxide than titanium dioxide powder.