毕业论文移动版

摘要：环境污染和能源危机给人类的发展造成了巨大的阻碍。新兴光催化技术为解决这一难题提供了一条有效途径。常用光催化剂TO2等因其对太阳能利用率低，被限制大规模推广使用。因此，研发具有高催化活性的催化剂具有重大意义。新型非金属半导体石墨烯相氮化碳（g-C3N4）由于其优异的化学性质以及光学性能备受关注。本文采用不同的温度热缩聚尿素制备g-C3N4，探究温度对光催化剂的影响；采用水热法复合g-C3N4与WO3，构建g-C3N4基异质结，提高光生载流子的分离效率，进而实现提高光催化活性的目标。本论文的具体内容如下：

(1)g-C3N4的制备以及探究最佳焙烧温度

通过在450℃~630℃温度下热缩聚尿素前驱的处理方法，制得不同温度纯相的g-C3N4催化剂，通过X-射线粉末衍射、扫描电镜、透射电镜、傅立叶红外光谱仪等测试方法对其结构、形貌进行表征。结果表明随温度升高，氮化碳由体相转变为纳米类石墨烯相，其结构和性能发生很大变化，并且通过催化降解罗丹明B实验测试光催化性能，结果表明，在570℃下制备得到的g-C3N4催化活性最佳。

(2)制备g-C3N4基复合光催化剂，提高光生电子-空穴对的分离效率采用超声辅助水热法，在拥有片层结构g-C3N4的表面搭载纳米颗粒三氧化钨（WO3）,合成WO3/g-C3N4复合光催化剂。通过多种检测方法对所制备样品的形态，结构，组成等进行表征。通过催化降解RhB实验对样品光催化活性做出评价，并对实验过程中影响晶体生长的可控条件水热反应时间、单体复合的配比度做出调控，探究最适反应时间、配比度对复合光催化剂性能的影响。实验结果表明，当单一组元WO3与g-C3N4配比度为1:1，水热反应时间为18小时所制备的光催化剂具有最高的催化活性。

关键词:光催化剂;g-C3N4;水热法;罗丹明B

Abstract：Environmental pollution and energy crisis has caused great obstacles on the development of human beings, emerging light catalytic technology provides an effective solution to solve the problem . Commonly used photocatalyst TO2 is limited to large-scale promote and use due to its low utilization of solar energy. Therefore, it is of great significance to study a catalyst with high catalytic activity. The new non-metallic semiconductor graphene phase carbonitride (g-C3N4) has attracted much attention for its excellent chemical properties and optical properties. In this paper, g-C3N4 was prepared by thermally condensed urea at different temperature , and the effect of temperature on the photocatalyst performance was studied. The g-C3N4 heterojunction was constructed by compounding g-C3N4 and WO3 with hydrothermal method aiming  to  improve the separation efficiency of photogenerated carriers and to improve the photocatalytic activity. The main contents of this paper are as follows:

（1）Preparation of g-C3N4  and exploration of optimum roasting temperature

The pure phase g-C3N4 catalyst at different temperatures was prepared by heat-blending the urea precursor from 450°C to 630°C .The structure and morphology were characterized by X-ray powder diffraction, Scanning electron microscopy,Transmission electron microscopy and Fourier  transform  infrared spectroscopy . The results show that the structure of the sample transforms the body phase into the nanometer graphene phase and the properties of the nanocrystalline graphene are greatly changed with the raising of the temperature.In addition,the photocatalytic activity of prepared samples was evaluated by photocatalytic degradation of the Rhodamine B  test.

The results show that prepared at the temperature of 570 ℃of the g-C3N4  has best  catalytic

activity .

（2）Preparation of g-C3N4 based composite photocatalyst to improve the separation efficiency of photo-generated electron-hole pairs g-C3N4/WO3 composite photocatalyst was prepared by ultrasonic assisted hydrothermal method , nanoparticles of tungsten trioxide (WO3) was added to the surface of graphene phase carbonitride (g-C3N4) . The morphology, structure and composition of the prepared samples were characterized by a variety of detection methods. The photocatalytic activity of prepared samples was evaluated by photocatalytic degradation of RhB. The influence of the optimum reaction time and the ratio on the performance of the composite photocatalyst was studied by controlling the hydrothermal reaction time and the ratio of monomer compound in this control process.When the ratio of single component WO3 to g-C3N4 is 1: 1 and the hydrothermal reaction time is 18 hours, the prepared photocatalyst has the highest catalytic activity. (责任编辑：qin)