中文摘要：

提出了一种程序升温制备高光催化活性g-C3N4的方法.以硫脲为前驱体,测得并分析了其TG/DSC曲线.基于在不同相转变温度条件下前驱体的化学转化,采用程序升温的方法制备了类石墨相氮化碳g-C3N4.采用SEM、TEM、FTIR、DRS、PL等技术,对所制g-C3N4的化学结构、形貌和光学性质进行了表征,并探究了不同程序升温方式对g-C3N4光催化性能的影响.结果表明,在硫脲相转变温度为260℃和426℃各保温1 h,550℃保温4 h,所制g-C3N4为疏松层状堆叠的块状颗粒.扩散反射光谱以及荧光光谱分析表明：采用该程序升温方式可提高g-C3N4光生电子-空穴对的分离效率.以罗丹明B为模型污染物,评价了所得g-C3N4的光催化活性.相较其它升温方式制备的g-C3N4,采用提出的程序升温热聚法制备的g-C3N4可提高罗丹明B的可见光催化降解速率达3倍.这种光催化活性的增强主要归因于其更大的比表面积和更高的光生电子-空穴分离效率.

英文摘要：

A programmed synthesis method was developed to prepare highly efficient photocatalytic g-C3N4. The TG/DSC thermograms were acquired and analyzed by using thiourea as the precursor. g-C3N4 was prepared by programmed（a multi- step temperature control） thermal polycondensation method based on the chemical conversion of precursor at different phase transformation temperatures. The textural structures,optical and electronic properties of the g- C3N4 were systematically characterized by Scanning Electron Microscopy,Transmission Electronic Microscopy,X- ray Diffraction,Fourier Transform Infrared Spectroscopy,Diffuse Reflectance Absorption Spectroscopy and Fluorescence Spectroscopy. The effects of the multi-step temperature control during the g-C3N4 preparation were investigated on the photocatalytic performance of g- C3N4. It was found that that the obtained g-C3N4 was composed of loosely stacked bulky sheets by keeping the temperature at 260 ℃ of the phase transformation temperature of thiourea for 1 h,then at 426 ℃ for another 1 h,and finally at 550 ℃ for 4 h. The diffuse reflectance absorption and fluorescence spectroscopic analysis indicated that the programmed synthesis promoted the dissociation of the photo-generated electron-hole pairs. The photocatalytic activity of the obtained g-C3N4 was evaluated by using Rh B as a model organic pollutant. The g-C3N4 photocatalyst obtained with the presently developed programmed synthesis method increased the photocatalytic degradation rate of Rh B by about 3 times in comparison with the g-C3N4 prepared by a conventional method. The enhanced photocatalytic performance of the obtained g- C3N4 was attributed to the increased specific surface area and improved separation of photo-generated electron-hole pairs.