One-Step Hydrothermal Synthesis of an Orthorhombic WO<sub>3</sub>·H2O/TiO<sub>2</sub> Heterojunction and its Photocatalytic Activity

The main issues that limit the large-scale application of TiO 2 in photocatalysis is its low utilization of solar energy and high recombination rate of photogenerated charges. To overcome these limitations, a type II WO 3 ·H 2 O/TiO 2 heterojunction has been prepared via a one-step mild hydrothermal method that uses Na 2 WO 4 ·2H 2 O and P25 as the starting materials and proceeds at 150°C without requiring any post-heat treatment for crystallization, special solvents or additives. The XRD and HRTEM results show that the prepared powders were composed of orthorhombic WO 3 ·H 2 O and TiO 2 , and demonstrate the existence of the WO 3 ·H 2 O/TiO 2 heterojunctions. The photocatalytic activity of the as-prepared WO 3 ·H 2 O/TiO 2 heterojunction powders was investigated by using the degradation of phenol. The WO 3 ·H 2 O/TiO 2 heterojunction powders exhibited the best photocatalytic performance when the nominal W/Ti ratio was 6.57%, and showed better photocatalytic performance than commercial P25 and orthorhombic WO 3 ·H 2 O.