| The photocatalysis technique is considered to be one of the effective methods in the fields of treating waste water,photoredox water splitting and purifying indoor environment.Graphitic carbon nitride?g-C3N4?is a metal-free semiconductor photocatalyst,g-C3N4 has become one of the hot spots in the field of photocatalyst research,because of its low cost,nontoxicity,versatile optical,chemical/thermal stability.However,the practical applications of traditional bulk-like g-C3N4 are limited by the low specific surface area,poor conductivity and high recombination rate of photogenerated electron-hole pairs.Therefore,great efforts have been carried out from controlling the morphologies and constructing heterostructure to enhance the photocatalytic performance of g-C3N4.The g-C3N4 with bulk,rod,spheric,alveolate morphologies were successfully prepared by using different experimental methods.The samples with different morphologies were characterized by X-ray powder diffraction,Fourier transform infrared spectrometry,Scanning electron microscopy,nitrogen physisorption,UV–vis diffuse reflection spectroscopy,X-ray photoelectron spectroscopy.The photocatalytic performances were evaluated by photoredox water splitting and rhodamine B degradation.Results revealed that the samples with different morphologies still existed the same phase structure,and the rod-like g-C3N4 exhibited a largest specific surface area,the maximum photogenerated carrier separation efficiency and optimized photocatalytic activity.Among all materials,the hydrogen evolution rate of rod-like g-C3N4 was 160.9?mol h-1 g-1,which was 1.34 times than that of bulk g-C3N4.After 6 hours of illumination,the photodegradation efficiency of rod-like g-C3N4 for RhB was 75%,which was 1.31 times than that of bulk g-C3N4.The heterojunction photocatalysts that TiO2/rod-like g-C3N4?TiO2/RCN,the ratio of TiO2 to RCN was 1:5,1:3,1:1,3:1,5:1,respectively?were prepared by hydrothermal method using tetrabutyl titanate and traditional bulk-like g-C3N4 as raw materials.The photocatalytic performances of TiO2/RCN were evaluated by photoredox water splitting and rhodamine B degradation test.The mechanism of the photocatalysts was investigated by determination of reactive species in the photocatalytic reactions.Results revealed that the synergistic effect between TiO2 and rod-like g-C3N4 can enhance the photocatalytic activities.When the molar ratio of TiO2 to rod-like g-C3N4 was 1:1,the hydrogen evolution rate was 361.8?mol h-1 g-1,which was 7.99 times more than TiO2 and 2.25times than that of rod-like g-C3N4.After 3.5 hours of illumination,the photodegradation efficiency of TiO2/RCN for RhB was 98.6%,which was 1.24 times than that of TiO2 and1.71 times than that of rod-like g-C3N4.In addition,the photodegradation process of RhB was analyzed by means of LC-MS,and the possible intermediates were proposed. |
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