Fabrication of nano TiO2@graphene composite: Reusable photocatalyst for hydrogen production, degradation of organic and inorganic pollutants

• In-situ decoration of TiO2 nanoparticles onto RGO by sol–gel.
• Size uniformity and appropriate dispersion of TiO2 onto the RGO surface.
• RGO/TiO2 composite as an efficient photocatalyst for hydrogen production.
• Excellent photocatalyst for the degradation of methylene blue dye.
• Photocatalytic reduction of Cr(VI) to Cr(III) under UV-irradiation.

Titanium dioxide (TiO2) nanoparticles decorated reduced graphene oxide (RGO) composites were fabricated via an in-situ sol–gel route. TEM analysis revealed that the TiO2 nanoparticles of a size less than 8 nm were coated onto the RGO surface. The TiO2 nanoparticles on the RGO surface were spherical and well dispersed. The nanocomposite exhibited enhanced photocatalytic activity for hydrogen (H2) production with a rate of 203 μmol/h, which was higher than that of TiO2 (35 μmol/h) and P25 (51 μmol/h). This is because the TiO2 nanoparticles on the RGO sheets can capture light energy and facilitate excited electron transfer for H2 production via the RGO, which acts as an efficient electron mediator. The nanocomposite also showed efficient photocatalytic degradation of methylene blue and photo-reductive conversion of Cr(VI) with a rate of 2.2 and 1.7 times higher than that of P25, respectively. These degradation results indicated that the photocatalytic performance of the nanocomposite was greatly enhanced by the improved adsorption performance and separation efficiency of the photo-generated carriers. The nanocomposite maintained a higher level of activity even after four recycles.