| The utilization of semiconductor photocatalysts for the treatment of organic pollutants and hydrogen production from water splitting has been regarded as a promising method to solve environment issue and energy crisis.Among various photocatalyst materials,titanium dioxide（TiO2）is the most famous photocatalysts owing to its low cost,high photocatalytic activity,good stability and nontoxicity.Nevertheless,the wide band-gap and the rapid recombination of photoinduced electron-holes are major drawbacks in its poor photocatalytic activity.The black TiO2 displayed much higher light absorbance capacity than the pristine white TiO2,which was attributed to a large amount of Ti3+ and oxygen vacancy（Ov）.To further expand the TiO2 material practical application,it is necessary to enhance photoinduced electron-hole pairs separation capability,and semiconductor coupling is an efficient method to reduce the recombination of photoinduced electron-hole pairs.Graphite-like carbon nitride（g-C3N4）has been reported to be a non-toxic,stable and facile metal-free visible light photocatalyst.The band-gap of g-C3N4 is 2.7 eV,indicating a strong absorption in visible light region.TiO2/g-C3N4 composite have shown improved visible-light photocatalytic performance in dye degradation and H2 evolution.This paper prepared TiO2/g-C3N4 and black TiO2 nanobelts/g-C3N4 composite.The prepared samples are evidently investigated by X-ray diffraction,Fourier transform infrared spectroscopy,scanning electronl microscopy,transmission electron microscopy,X-ray photoelectron spectroscopy,N2 adsorption,and UV-visible diffuse reflectance spectroscopy,respectively.And evaluate the ratio of raw materials and calcination temperature on the properties of photocatalytic materials by choosing methyl orange solution as target pollutant,and evaluate the photocatalytic activity for hydrogen evolution under the simulated solar light（AM 1.5）irradiation.The research results of this paper are as follows:（1）With tetrabutyl titanate and melamine as raw materials,the TiO2 nanoparticles was prepared by hydrothermal method and the TiO2/g-C3N4 composite was prepared by calcination method.The results of experiment shows that the photocatalyst exhibited excellent photocatalytic activity when the ratio of raw materials is 1:6 and the calcination temperature is 550 ℃.（2）Black TiO2 nanobelts/g-C3N4 composite was fabricated through a simple hydrothermal-calcination process and an in-situ solid-state chemical reduction approach.The results show that special laminated heterojunctions are formed between black TiO2 nanobelts and g-C3N4,which favor the separation of photogenerated electron-hole pairs.Furthermore,the presence of Ti3+ and g-C3N4 greatly enhance the absorption of visible light.The black TiO2 nanobelts/g-C3N4 composite exhibits high photocatalytic activity for degradation of methyl orange（95%）and hydrogen evolution（555.8 μmol h-1 g-1）under visible light irradiation.The apparent reaction rate constant（k）of black TiO2 nanobelts/g-C3N4 composite is～9 times higher than that of pristine TiO2. |
