Photocatalytic activity and mechanism of bisphenol a removal over TiO2−x/rGO nanocomposite driven by visible light

By Lu Xu, Lei Yang, E. Johansson, Yuanhao Wang, P. Jin. Chemical Engineering Journal, 2018

182 citations recorded by the source corpus.

In the present study, Ti3+ and oxygen vacancies (Ti3+/O-v) self-doped TiO2 and coupled with a reduced graphene oxide (rGO) nanocomposite (TiO2-x/rGO) was successfully synthesized via a facile hydrothermal-calcination method for the efficient degradation of bisphenol A (BPA) under visible light. The results of XPS, ERP and TEM analyses revealed that the presence of Ti3+/O-v in the lattice of TiO2-x/rGO leads to the narrowed band gap and enhanced visible light harvesting. The chemical bonds (TieOeC) between TiO2-x and rGO act as the channel for electron transfer, consequently resulting in the efficient charge separation, which was investigated and confirmed by such methods as PL spectra and time-resolved PL spectra. In addition, the coupling of TiO2-x and rGO could strongly suppress the aggregation of TiO2-x particles and therefore improve the adsorption of organic pollutants. For the synergistic effect of the three preeminent features mentioned above, TiO2-x/rGO exhibited a 6.16-, 2.92-and 2.55-fold faster reaction rate for BPA degradation than that of pristine TiO2, TiO2/rGO and TiO2-x, respectively. Moreover, the effects of the initial substrate concentration, initial solution pH, catalyst dosage and inorganic anions on BPA removal were also investigated in depth. EPR measurements indicated that center dot O-2(-) as the major oxidizing species, is responsible for the degradation of BPA. Next, the feasible pathway of BPA degradation by TiO2-x/rGO was proposed based on the analysis of intermediate products. Finally, the mechanism of the enhanced photocatalytic performance by TiO2-x/rGO under visible light was discussed. Based on these results, the TiO2-x/rGO nanocomposite could be an efficient and promising photocatalyst for the degradation of organic pollutants in water.

Subfields: Materials Chemistry, Renewable Energy, Sustainability and the Environment

View Paper: https://www.semanticscholar.org/paper/e8f58c5633c9e90808c8a960f3ab1516d44ba926