New insights into the relationship between photocatalytic activity and TiO2–GR composites

Abstract

TiO₂–graphene (TiO₂–GR) composites were synthesized via hydrothermal methods in an ethanol–water solvent. The photocatalytic oxidation, photocatalytic reduction and photoelectrochemical properties were systematically investigated to explore the real role of graphene in the TiO₂–GR composite photocatalysts. The pollutant degradation and adsorption results strongly indicated that the composited graphene in TiO₂–GR cannot enhance the photocatalytic oxidation activity in the degradation of pollutants. The migration process of photo-generated holes in the photocatalytic oxidation reaction is the rate-determining step, which cannot be promoted by the composited graphene in TiO₂–GR. However, composited graphene can promote the migration of photo-generated electrons in TiO₂–GR due to its excellent conductivity, which mainly enhances the H₂ evolution performance and photoelectrochemical properties.