Adsorption and in-situ photocatalytic synergy degradation of 2,4-dichlorophenol by three-dimensional graphene hydrogel modified with highly dispersed TiO2 nanoparticles

Abstract

A highly dispersed TiO2 nanoparticle-modified three-dimensional graphene hydrogel composite (TiO2-rGH) was successfully prepared by a hydrothermal method. Based on adsorption and photocatalytic degradation at the same active site, the synergistic system exhibited excellent catalytic degradation performance, which could fully mineralize the 2,4-dichlorophenol (40 mg/L) solution after 20 min. The reaction rate constants were 8 and 13 times those of TiO2 and rGH, respectively. Meanwhile, the assembly of two-dimensional graphene sheets with hybrid TiO2 nanoparticles to construct the three-dimensional graphene hydrogel structure not only increases the specific surface area of the composite but also builds more charge transport channels. The results showed that the specific surface area of TiO2-rGH was 151.46 m2/g, which was approximately 5 times that of rGH, and the adsorption activity for 2,4-dichlorophenol was doubled. In addition, the photocurrent density of TiO2-rGH was 11 times that of TiO2 nanoparticles; thus, the TiO2-rGH composites exhibited better adsorption and photocatalytic degradation performance than rGH and TiO2. More importantly, the three-dimensional graphene hydrogel composite has excellent stable degradation performance and solves the problem that the catalyst is difficult to recycle, showing great potential in practical applications.