Enhancing Free Cyanide Photocatalytic Oxidation by rGO/TiO 2 P25 Composites.

Graphene-TiO 2 composites have been investigated in various photocatalytic reactions showing successful synergy compared to pristine TiO 2 . In the present work, graphene oxide (GO) was synthesized by the Hummers method and then reduced graphene oxide-TiO 2 composites (rGO/TiO 2 ) were obtained by an in situ GO photoreduction route. X-ray diffraction, FTIR, Raman, UV-vis DRS, and photoluminescence were the main characterization techniques. The obtained composites containing 1 and 3 wt.% rGO were evaluated in the cyanide (50 mg/L) oxidation and Au-cyanide complex (300 mg/L) degradation under UV-A light. The composites showed higher photocatalytic activity than TiO 2 , mainly with the 1% rGO content. Cyanate and gold nanoparticles, deposited on the photocatalyst's surface, were the main byproducts during the photocatalyst assessment. The improved photocatalytic activity of the composites was attributed to a higher rate of electron transfer and a lower rate of charge recombination due to the chemical interaction of rGO with TiO 2 .