Crystalline phase engineering in WO3/g-C3N4 composites for improved photocatalytic performance under visible light

Abstract

The photocatalytic performance of a semiconductor material is significantly related to its crystalline phase, thus, crystalline phase engineering is of importance for designing the semiconductor composites fabricated between two semiconductor materials. In this work, WO3/g-C3N4 composites was taken as an example, we designed and prepared the WO3/g-C3N4 composites with different crystalline phases of WO3. The important role of the crystalline phase of WO3, which is hexagonal phase (h-WO3), monoclinic phase (m-WO3), and mixed phases of h-WO3 and m-WO3 on the morphology, photoabsorption property, charge separation efficiency, and photocatalytic activity of the WO3/g-C3N4 composites were systematically investigated. By evaluating the photocatalytic degradation of RhB, it is found that the highest photocatalytic activity was achieved by WO3/g-C3N4 with 25 wt% h-WO3 and 75% g-C3N4 (H1G3). The enhanced photocatalytic performance of H1G3 was mainly attributed to the improvement in the separation efficiency of photogenerated electron-hole pairs, which was confirmed by surface photovoltage results. Our work sheds a light on the design of composite photocatalysts based on semiconductor oxides.