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

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.

Automated summary

In this study, a high-efficiency photocatalyst for detoxification of Cr(vi) ions was developed by co-doping N and S, constructing anatase/rutile junction, and regulating morphology of TiO2 arrays. The optimized co-doped TiO2 nanoflower arrays showed excellent photoactivity towards Cr(vi) reduction. The enhanced photocatalytic activity can be attributed to improved carrier separation efficiency and narrowed band gap.