Synthesis of TiO₂ nanosheet photocatalysts from exfoliation of TiS₂ and hydrothermal treatment

TiO₂ nanomaterials with platelet or nanosheet morphologies can offer improved properties for photocatalytic applications, but established methods to produce them typically require structure-directing agents since anatase-phase TiO₂ does not have a layered structure. In the present work, the preparation of TiO₂ nanosheets by the chemical oxidation of TiS2 nanosheets is demonstrated. Electrochemical exfoliation of bulk TiS2 into TiS2 nanosheets, followed by the hydrothermal treatment at 180 °C for 14 h is performed. The results show that polycrystalline TiO₂ nanosheets with the anatase structure are formed, and that the nanosheet morphology can still be maintained after the hydrothermal treatment. The TiO₂ nanosheets show good photocatalytic activity for the degradation of methylene blue, but the performance is negatively affected by the residual carbon black that was needed in the TiS2 electrode to enable electrochemical exfoliation. These results show that conversion of TiS2 nanosheets to TiO₂ nanosheets is a promising synthetic strategy but highlights how the interfacial properties of the obtained materials could be affected by ancillary components in the preparation method.