High-performance photodetectors and enhanced photocatalysts of two-dimensional TiO2 nanosheets under UV light excitation

Due to the large surface area-to-volume ratio and rapid electron transfer, two-dimensional (2D) TiO₂ nanosheets with ultrathin thicknesses are synthesized by using a bottom-up strategy and these self-assembled nanosheet (NS)-based photocatalysts and photodetectors were explored for the first time. The influence of calcination temperature on microstructures and photocatalytic activity of TiO₂ nanosheets were discovered and presented. The as-obtained TiO₂ nanosheets were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) analysis, Fourier transform infrared (FTIR) spectroscopy, UV-vis spectrophotometry, and X-ray photoelectron spectroscopy (XPS). The following heat treatment process induced phase evolution from rutile to anatase. The TiO₂ nanosheets calcined at 500 °C exhibited the best activity for photo-degradation of organic dyes under UV light irradiation. The obtained photodetector exhibits excellent performance with a high photocurrent to dark current ratio and fast response and recovery times. Additionally, we demonstrated that the device may have potential applications in the future low-power optoelectronics system.Due to the large surface area-to-volume ratio and rapid electron transfer, two-dimensional (2D) TiO₂ nanosheets with ultrathin thicknesses are synthesized by using a bottom-up strategy and these self-assembled nanosheet (NS)-based photocatalysts and photodetectors were explored for the first time. The influence of calcination temperature on microstructures and photocatalytic activity of TiO₂ nanosheets were discovered and presented. The as-obtained TiO₂ nanosheets were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) analysis, Fourier transform infrared (FTIR) spectroscopy, UV-vis spectrophotometry, and X-ray photoelectron spectroscopy (XPS). The following heat treatment process induced phase evolution from rutile to anatase. The TiO₂ nanosheets calcined at 500 °C exhibited the best activity for photo-degradation of organic dyes under UV light irradiation. The obtained photodetector exhibits excellent performance with a high photocurrent to dark current ratio and fast response and recovery times. Additionally, we demonstrated that the device may have potential applications in the future low-power optoelectronics system.

Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr09248e