In situ hydrothermal synthesis of TiO2-RGO nanocomposites for 4-nitrophenol degradation under sunlight irradiation

Different amounts (0, 1.0, 3.0, 5.0 and 10.0 wt%) of reduced graphene oxide (RGO) were successfully immobilized to the surface of TiO2 nanoparticles through a hydrothermal process. With addition of RGO, the particle size decreased and the surface area and pore volume increased, resulting in improvement of the reactants' diffusion and contact area. RGO could be hybridized with titanium atoms, leading to decreasing of the gap energy of TiO2 and more efficient utilization of the solar energy. Hence, the photocatalytic activity of TiO2-RGO composites for 4-nitrophenol degradation was improved accordingly. However, excess amount of RGO (>= 10.0 wt%) brought about easier recombination of photoelectrons and holes, causing a lower quantum efficiency and photocatalytic activity. The center dot OH radicals were the main active species during the degradation process, but the involvement of center dot O-2(-) radicals could not be neglected. The pathways for mineralizing of 4-nitrophenol over TiO2-RGO composites under sunlight irradiation were also proposed.

Automated summary

The study investigated the influence of different amounts of reduced graphene oxide on TiO2 nanoparticles. Results showed that the addition of RGO could improve reactant diffusion and contact area, enhancing photocatalytic activity; however, an excess amount of RGO would reduce photocatalytic efficiency.