Titanium dioxide/reduced graphene oxide nanocomposites as effective photocatalytic for hazardous 4-nitrophenol

Abstract

Titanium dioxide/reduced graphene oxide nanocomposite (TiO2/rGO NCs) was prepared using various hydrothermal strategies as a highly efficient photocatalyst. The crystal structure, morphology, elemental distribution, chemical structure, optical properties, and electrical conductivity of TiO2/rGO NCs were studied to investigate the effect of the incorporation of rGO with TiO2NPs on these properties. The TiO2/rGO NCs surface exhibits thin sheets of rGO with TiO2NPs distributed on the sheets. The successful incorporation between rGO and TiO2NPs was confirmed by EDX maps, IR spectrum, and XRD patterns. Compared with TiO2NPs, a tiny reduction in the crystallite size and an increase in the microstrain was found; in addition, the TiO2/rGO NCs exhibit a low direct bandgap energy, a high electrical conductivity, and excellent photoconductivity. On the other hand, different amounts of 4-nitrophenol (4-NP) were used to investigate the photocatalyst degradation efficiency of TiO2NPs and TiO2/rGO NCs under UV irradiation. The higher degradation efficiency after 120 min was for TiO2/rGO NCs with 5 mg/L and 10 mg/L of 4-NP, with 94% and 91% values, respectively. The first-order kinetic constant (k1), the kinetic rate constant of the surface reaction (ks) and the adsorption equilibrium constant (KL) were evaluated. The KL of TiO2NPs and TiO2/rGO NCs is 0.003 and 0.182 (mgL−1)−1, and the ks is 2.53 and 0.21 mgL−1.min−1, respectively.