Graphitic C3N4 nanosheet-sensitized brookite TiO2 to achieve photocatalytic hydrogen evolution under visible light

Brookite TiO2 was regarded as one of the most promising semiconductor materials in the field of photocatalytic H-2 production. However, the low utilization efficiency of solar energy and high recombination rate of photo-induced carriers have hampered its application. To solve the issues stated above, novel g-C3N4 nanosheet/brookite TiO2 composite materials (TCN) with different contents of g-C3N4 nanosheets have been synthesized via an in situ TiO2 growth approach. The as-prepared TCN samples showed much higher visible-light-driven photocatalytic hydrogen evolution rate than pure g-C3N4 nanosheets. The optimal TCN sample with a g-C3N4 nanosheet content of 50% exhibited a H-2 evolution rate of 68.76 mu mol h(-1), which was 1.55 times greater than pure g-C3N4 nanosheets and 6.8 times greater than bulk g-C3N4 under visible light irradiation. Results from X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy suggest that close interfacial connections between g-C3N4 nanosheets and brookite TiO2 had been formed. Photoelectrochemical tests confirmed that the enhancement of photocatalytic H-2 evolution activity resulted from superior electron transport and charge separation ability of the TCN composite materials.