Structural design of hexagonal/monoclinic WO3 phase junction for photocatalytic degradation

Photogenerated carriers separation is the bottleneck step to determine the photo-catalytic efficiency in photocatalysis. Fabrication of the phase junction has been demonstrated to be efficient in the photogenerated carriers separation. It is important to control the phase composition in phase junction. In this work, photoatalysts with tunable hexagonal/monoclinic WO3 phase junction (h/m-WO3) were prepared by presice controlling the h-WO3 -> m-WO3 phase transformation. Based on in-situ XRD results, a suitable calcination temperature (400 degrees C) was selected to realize the phase transition from h-WO3 to m-WO3. It is found that the junction structures can be easily regulated with increasing calcination time at 400 degrees C. The photocatalytic degradation of RhB results indicate that h/m-WO3 sample with 88.1 wt% h-WO3 exhibits the maximum value. The results from electrochemical impedance spectroscopy (EIS) and surface photo-voltage (SPV) indicate that the separation of photo-generated carriers can be greatly improved by the phase regulation in WO3 with phase junction.