Modulation of titania nanoflower arrays transformed from titanate nanowire arrays to boost photocatalytic Cr(vi) detoxification

Abstract

Toxic heavy metal ions, typically Cr(VI)-based ions, in effluents from industrial processes have caused inevitable harm to biological tissues and the whole food chain. It is urgent to develop high-efficiency photocatalysts for the detoxification of Cr(VI) ions. In this study, the N and S co-doping, anatase/rutile junction construction, and morphology regulation of TiO₂ arrays were successfully achieved by an acid bath treatment of titanate arrays with the assistance of potassium persulfate (PPS). It was found that the optimized S, N co-doped anatase/rutile TiO₂ nanoflower arrays show excellent photoactivity towards the reduction of lethal Cr(VI) to low-toxic Cr(III). The reaction rate constant k reached 2.0 h⁻¹, which is about 6.7, 2.3, and 2.2 times that of the anatase TiO₂ nanowire arrays, TiO₂ nanoflowers obtained without PPS, and the nanoparticulate P25 film, respectively. Furthermore, the optimized photocatalyst exhibits high stability and reusability. The enhanced photocatalytic activity can be attributed to the improved separation efficiency of photogenerated carriers and the narrowed band gap. It could provide an effective strategy for the design and synthesis of high-performance photocatalysts in wastewater remediations.