Mesoporous WO/TiO spheres with tailored surface properties for concurrent solar photocatalysis and membrane filtration.

The strategical integration of membrane water filtration with semiconductor photocatalysis presents a frontier in deep purification with a self-cleaning capability. However, the membrane fouling caused by the cake layer of the reclaimed TiO nanoparticles is a key obstacle. Herein, mesoporous WO/TiO spheres (∼450 nm in diameter) consisting of numerous self-assembled WO-decoated anatase TiO nanocrystallites are successfully prepared via a facile wet-chemistry route. The decoration of monolayered WO significantly affects the surface, photocatalytic, and optical properties of original mesoporous TiO spheres. XRD and Raman analyses show the presence of monolayered WO suppresses the crystal growth of TiO during the calcination process, significantly improves the surface acidity, and causes an obvious red shift in absorption edge. These favorable textural properties, coupling the enhanced interfacial charge carrier separation, render mesoporous WO/TiO spheres with a superior photocatalytic activity in degradation of methylene blue under UV, visible, and solar light irradiations. The optimal molar ratio of W/Ti is examined to 6%. The synthesized mesoporous WO/TiO spheres also show much higher flux during membrane filtration in both dead-end and cross-flow modes, suggesting a promising photocatalyst for concurrent membrane filtration and solar photocatalysis.