Coupling of W-Doped SnO2 and TiO2 for Efficient Visible-Light Photocatalysis

摘要

Five mol % tungsten-doped tin oxide (Wo.05Sno.95O2, TT05) was prepared by co-precipitation of SnCl4-5H2O and WCU, followed by calcination at 1000 °C. The as-prepared TT05 was in the pure cassiterite phase with a particle size of-50 nm and optical bandgap of 2.51 eV. Herein it was applied for the formation of TT05/TiO2 heterojunctions by covering the TT05 surface with TiO2 by sol-gel method. Under visible-light irradiation (X >420 nm), TT05/Ti02 showed a significantly high photocatalytic activity in removing gaseous 2-propanol (IP) and evolving CO2. It is deduced that its high visible-light activity is caused by inter-semiconductor hole-transfer between the valence band (VB) of TT05 and TiO2, since the TT05 nanoparticle (NP) exhibits the absorption edge at-450 nm and its VB level is located more positive side than that of TiO2. The evidence for the hole-transport mechanism between TT05 and TiO2 was also investigated by monitoring the hole-scavenging reaction with 1,4-terephthalic acid (TA).