Enhanced photocatalytic degradation of a phenolic compounds’ mixture using a highly efficient TiO2/reduced graphene oxide nanocomposite

A nanocomposite (namely rGOTi) was prepared by loading 0.33 weight percent of reduced graphene oxide (rGO) on commercial TiO2 nanoparticles using a hydrothermal method. The as-prepared nanocomposite was characterized using surface and bulk analytical techniques such as X-ray photoelectron spectroscopy, X-ray diffraction, and Fourier transform infrared and Raman spectroscopies. Also, the surface area was measured using the Brunauer–Emmett–Teller technique. In addition, the UV–Vis diffuse reflectance spectroscopy measurements have shown that the band gap energy for TiO2 was lowered from 3.11 to 2.96 eV when it was composited with rGO to form the rGOTi. The kinetics of the degradation of phenol, p-chlorophenol, and p-nitrophenol (separate or mixed) and their intermediates using the as-prepared nanocomposite photocatalyst compared to the bare TiO2 nanoparticles was tested using UV and Xenon lamps (mainly a visible light source) as photoexcitation sources in the presence and absence of H2O2. In general, it was revealed that the photocatalytic activity of the rGOTi using a visible light source, in the presence of H2O2, is significantly higher than that when (1) a UV lamp and/or (2) TiO2 nanoparticles were used. Also, the presence of H2O2 led to higher degradation rates of all the phenolic compounds regardless the type of photoexcitation source.