Published online by Cambridge University Press: 02 August 2011
Titanate nanotube (TNT) was prepared by alkaline hydrothermal method starting from TiO2 (P25), and then CdS-TNT was prepared for visible light harvesting by immersing TNT in Cd(CH3COO)2 and then (NH2)2CS aqueous solutions subsequently and heat treated at specialtemperature. After loading with Pt, photocatalytic reduction of gas phase CO2 with water vapor was carried out under UV-VIS and visible light irradiation. The results showed that the main reaction products were CH4, C2H4, C2H6 and H2, which were online characterized by gaschromatography when the flow rate of 5000 ppm CO2 is 0.35 ml/min. The hydrogenation process also realized under visible light illumination for Pt-CdS/TNT and producted 0.44 μmol/min CH4. The maximum yield of methane reached about 130 μmol/min when Pt-CdS/TNTwas irradiated with UV-Vis light. The time profile for production yield increased steadily with time up to about 6–7 h, then a decrease of the reaction rate occurred. It is suggested that thadsorption of intermediate products CO, O2 etc. on Pt and the oxidation of Pt might be the reasons for the photocatalytic reaction deterioration.