Facile preparation of a TiO2 quantum dot/graphitic carbon nitride heterojunction with highly efficient photocatalytic activity.

In this article, mechanical grinding, an effortless and super-effective synthetic strategy, is used to successfully synthesize a TiO2 quantum dot (TiO2QD)/graphitic carbon nitride (g-C3N4) heterostructure. X-ray photoelectron spectroscopy results together with transmission electron microscopy reveal the formation of the TiO2QD/g-C3N4 heterostructure with strong interfacial interaction. Because of the advantages of this characteristic, the prepared heterostructure exhibits excellent properties for photocatalytic wastewater treatment. Notably, the optimum photocatalytic activity of the TiO2QD/g-C3N4 heterostructure is nearly 3.4 times higher than that of the g-C3N4 nanosheets used for the photodegradation of rhodamine B pollutant. In addition, the stability and possible degradation mechanism of the TiO2QD/g-C3N4 heterojunction are studied in detail. This method may stimulate an effective approach to synthesizing QD-sensitized semiconductor materials and facilitate their application in environmental protection.

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.