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.