Semiconductor/reduced graphene oxide nanocomposites derived from photocatalytic reactions

Graphene-based semiconductors nanocomposites were synthesized via a single-step photocatalytic reduction process. UV active titanium dioxide (TiO₂) and visible light driven photocatalysts (i.e. tungsten oxide (WO₃) and bismuth vanadates (BiVO₄)) with different conduction band energy levels were found efficient in transferring photogenerated electrons into graphene oxide (GO) thus reducing it to reduced graphene oxide (RGO). Simultaneously, nanocomposites of these particulate semiconductor and RGO sheet were obtained. X-ray photoelectron spectra revealed the 52-63% decrease in oxygen-containing carbon (hydroxyl and epoxy groups) of GO after illumination, indicating partial reduction of GO by excited photocatalysts. When made into thin films, photocurrent generation of these nanocomposites was enhanced by 160, 190 and 800%, respectively, for WO₃, TiO₂ and BiVO₄ as 5 wt% RGO was incorporated. These results demonstrate for the first time that a range of photocatalysts, not just TiO₂, can be used to reduce and incorporate GO into nanocomposites that have higher photoelectrocatalytic efficiencies than their parent materials.