Preparation of a Ti(0.7)W(0.3)O(2)/TiO(2) nanocomposite interfacial photocatalyst and its photocatalytic degradation of phenol pollutants in wastewater

A Ti(0.7)W(0.3)O(2)/TiO(2) nanocomposite interfacial photocatalyst was designed and prepared for the photocatalytic degradation of phenol pollutants in wastewater. The detailed properties of the Ti(0.7)W(0.3)O(2)/TiO(2) nanocomposite interface (NCI) were analyzed by XRD, SEM, EDX, DRS, UPS and XPS technologies, showing that anatase TiO(2) nanospheres (NSs) were uniformly dispersed on the surface of rutile Ti(0.7)W(0.3)O(2) nanoparticles (NPs) and formed the nanocomposite interface. The DRS and UPS results of 5 wt% Ti(0.7)W(0.3)O(2)/TiO(2) NCI indicated a greatly broadened light response range with a wavelength shorter than 527 nm and a shorter band gap energy of 2.37 eV. The conduction band of TiO(2) NSs, Ti(0.7)W(0.3)O(2) NPs and 5 wt% Ti(0.7)W(0.3)O(2)/TiO(2) NCI were measured based on the results of the valence band and band gap energy obtained via XPS and DRS, and then the energy level diagram of Ti(0.7)W(0.3)O(2)/TiO(2) NCI was proposed. The photocatalytic degradation of phenol at Ti(0.7)W(0.3)O(2)/TiO(2) NCI with different loading ratios of Ti(0.7)W(0.3)O(2) NPs was investigated under optimum conditions (i.e., pH of 4.5, catalyst dosage of 0.45 g L(−1) and phenol initial concentration of 95 ppm) under the illumination of ultraviolet visible light. Also, 5 wt% Ti(0.7)W(0.3)O(2)/TiO(2) NCI exhibited the highest photocatalytic activity, with the initial rate constant (k) calculated as 0.09111 min(−1). After recycling six times, Ti(0.7)W(0.3)O(2)/TiO(2) NCI showed good stability and recyclability. The involvement of superoxide radicals in the initial reaction at Ti(0.7)W(0.3)O(2)/TiO(2) NCI was evidenced by the use of a terephthalic acid (TA) fluorescent probe. Besides, UV-Vis spectroscopy, UHPLC-MS and GC-MS technologies were used to analyze the main intermediates in the photocatalytic degradation of phenol. The probable photocatalytic degradation mechanism of phenol at Ti(0.7)W(0.3)O(2)/TiO(2) NCI was also proposed.