Rapid photo-degradation of 2-chlorophenol under visible light irradiation using cobalt oxide-loaded TiO_2/reduced graphene oxide nanocomposite from aqueous media

摘要

The photocatalytic removal of 2-chlorophenol (2-CP) from water environment was investigated by TiO_2 -RGO-CoO. Cobalt oxide-loaded TiO_2 (TiO_2-CoO) supported with reduced graphene oxide (RGO) was synthesized using a sol-gel method and then annealed at 500 ℃ for 5 min. The material characteristics were analyzed by UV-Vis analysis, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy. Incorporation of cobalt oxide and RGO into the Ti_O2 system (TiO_2 -RGO-CoO) lowered the band gap energy to 2.83 eV, which greatly enhanced the visible light absorption. The TiO_2-RGO-CoO photocatalyst showed complete removal of 20 mg/L 2-CP within 8 h with the addition of 0.01% H_2O_2 under 100 W visible light irradiation. The photo-degradation efficiency of 2-CP (10 mg/L) was 35.2, 48.9, 58.9 and 98.2% for TiO_2, TiO_2-RGO, TiO_2-CoO and TiO_2-RGO-CoO, respectively, in the presence of visible light irradiation at solution pH of 6.0. The TiO_2-RGO-CoO photocatalyst retained its high removal efficiency even after five photocatalytic cycles.