Mesoporous TiO2 with WO3 functioning as dopant and light-sensitizer: A highly efficient photocatalyst for degradation of organic compound.

The suitable doping or modification on TiO2 holds promise for improving charge separation and extending light absorption range. Here, WO3 modifying reduced band gap mesoporous TiO2 (WO3/RM-TiO2) due to WO3 doping was successfully fabricated by immersing mesoporous TiO2 nanoparticles in the peroxotungstic acid sol with controllable reaction time (0-1 h). The W6+ ions were first incorporated into the TiO2 lattice to form WOTi bonds, resulting in the formation of WO3 doping TiO2. Then, WO3 nanoparticles gradually formed and attached on the TiO2 surface, constructing a novel heterojunction catalyst with WO3 serving as both dopant and light-sensitizer for TiO2. Photocatalytic activity of the resulting WO3/RM-TiO2 depends on the immersing duration in the peroxotungstic acid. The BET analysis shows that 0.5 h-WO3/RM-TiO2 has the largest pore volume of 0.491 cm3 g-1 and the highest surface area of 82.3 m2 g-1, whereas these values decline with prolonged immersing duration. As expected, the optimal efficiency in removing p-nitrophenol (PNP) is achieved over 0.5 h-WO3/RM-TiO2 under visible light irradiation, which is 2.33 times that of the unmodified M-TiO2. This should be attributed to the suitable WO3 doping and WO3 modification.