The effect of structure on the photoactivity of a graphene/TiO2 composite

Graphene/TiO2 composites have been investigated as promising novel photoactive materials. Graphene can slow the recombination of electron-hole pairs and act as a strong electron-collector in the graphene/TiO2 composite system. We designed and prepared four different structures of graphene/TiO2 composite film by chemical vapor deposition (CVD) and aerosol technique. The structure of the graphene/TiO2 composite had a significant effect on the photoactive properties, including the photocurrent and resistance under UV illumination. For the different composite structures, the presence of oxygen and water molecules, as well as the photo-generated electron collection efficiency, were the key factors that affect the photoactive properties. More importantly, the composite structure was a decisive factor for the stability of photocurrent and resistance. The composite of reduced graphene oxide (RGO) and TiO2 with irregularly stacked structure had a higher and stable photoresponse. This study could provide a basis for the structural design of photoelectrical devices based on graphene/TiO2.