Fabrication of highly visible active N, S co-doped TiO2@MoS2 heterojunction with synergistic effect for photocatalytic degradation of diclofenac: Mechanisms, modeling and degradation pathway

In this study, N,S co-doped TiO2@MoS2 nanocomposite were fabricated via a mild and effective hydrothermal method. The structural features and morphologies of nanocomposite were studied in detail by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis, (high resolution) transmission electron microscopy, X-ray photoelectron spectroscopy and UV–vis spectroscopy techniques. The results indicated that nitrogen and sulfur were successfully doped as interstitial doping in TiO2 lattices and simultaneously coupled with MoS2 to form the heterojunction nanostructure. The photocatalytic activity of N,S co-doped TiO2@MoS2 nanocomposite for diclofenac removal under visible LED light irradiation shows 5.0 times and 4.0 times higher than that of MoS2 and N,S co-doped TiO2, respectively. The kinetic model, effect of operational parameters (i.e. pH, catalyst dose, initial pollutant concentration) and mechanism for increasing visible-light photocatalytic activity of the heterostructure nanocomposite is discussed in detail. After six times cycle degradation of diclofenac the N,S co-doped TiO2@MoS2 nanocomposite exhibited steady photoactivity. This work introduces a highly-efficient heterostructure nanocomposite and a research pathway to evaluate the photocatalyst in shorter time which can help to design the system for the environmental pollution purification under sunlight irradiation.