Eco-friendly one-pot synthesis of ultradispersed TiO2 nanocrystals/graphene nanocomposites with high photocatalytic activity for dye degradation

Abstract

We report an eco-friendly one-pot hydrothermal synthesis of ultrafine TiO₂ nanocrystals (∼4.01 nm) homogeneously dispersed on the entire surface of graphene. Two specific contributions of glycerol, as the inhibitor to confine the growth and aggregation of primary TiO₂ nanoparticles and as the spacer to hinder the restacking of graphene nanosheets, for building the unique TiO₂/graphene nanoarchitectures have been clarified based on the systematic investigations. Compared with TiO₂/graphene hybrids synthesized without glycerol and commercial P25, the ultradispersed TiO₂ nanocrystals/graphene nanocomposites synthesized with the addition of glycerol have exhibited much higher photocatalytic activity for degradation of rhodamine B and methylene blue under visible light irradiation. The excellent recyclability and physicochemical stability of the as-synthesized nanocomposites have also been verified by the cycling photodegradation tests. The high photocatalytic activity and excellent stability of the as-synthesized nanocomposites are mainly attributed to the very high surface area (∼452 m² g⁻¹), efficient charge separation, and improved visible light absorbance, which originate from the advantageous nanoarchitectures such as ultradispersed and ultrasmall nature of TiO₂ nanocrystals as well as the intimate and maximum contact interfaces between TiO₂ and graphene.