类石墨相氮化碳的改性及光催化性能研究

发布时间：2018-02-27 14:14

本文关键词： g-C_3N_4 可见光响应型光催化剂光催化活性异质结　出处：《天津理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：由于能源短缺和环境恶化问题的持续威胁,类石墨相氮化碳(g-C_3N_4)作为一种新型的可见光响应型光催化剂已经成为热门研究课题。然而,体相g-C_3N_4由于存在着比表面积小,光生载流子易复合和太阳能利用率低等缺点而使得光催化活性较低。因此,本文旨在解决上述提出的体相g-C_3N_4的缺点来优化其光催化性能。取得的主要成果如下:1.在氩气气氛下,采用热剥离体相g-C_3N_4法制得超薄氮化碳(UGCN)纳米片。通过多种测试方法对样品的结构、形貌、比表面积和光电性质等进行了表征,并探讨了样品UGCN的光催化反应机理。与体相g-C_3N_4相比,样品UGCN的比表面积由58.5 m2g-1增大至131.2 m2 g-1,可见光吸收作用增强。在可见光照射下,样品UGCN光催化降解罗丹明B(RhB)的动力学速率常数是体相g-C_3N_4的6.1倍,同时,其产氢速率是体相g-C_3N_4的2倍。2.采用等离子体处理修饰g-C_3N_4的表面特性来优化其光催化性能。通过多种测试方法来考察等离子体处理对样品表面性质的作用,并探讨了改性g-C_3N_4的光催化反应机理。与体相g-C_3N_4相比,改性g-C_3N_4通过引入亲水性官能团(-OH、-COOH)增加了其亲水性程度。在可见光照射下,改性g-C_3N_4光催化RhB的降解率是体相g-C_3N_4的2倍。本实验方法为进一步优化光催化活性提供了一种新思路。3.采用一步煅烧法制备了新型的g-C_3N_4/CoO复合材料。通过多种测试方法对样品的结构、形貌、比表面积和光电性质等进行了表征,并探讨了g-C_3N_4/CoO复合材料的光催化反应机理。实验数据表明,g-C_3N_4/CoO-0.5 wt%复合材料在可见光照射下的光催化活性最高,其产氢速率是纯g-C_3N_4的3倍。g-C_3N_4/CoO复合材料光催化性能的显著提高主要是由于g-C_3N_4/CoO异质结中的能带结构匹配,这导致了可见光区域的光吸收作用增强,光生载流子分离效率提高。
[Abstract]:Due to the persistent threat of energy shortage and environmental degradation, graphite-like carbon nitride (GN) -like C _ 3N _ 4) has become a hot research topic as a new type of visible light-responsive photocatalyst. However, the bulk g-C _ 3N _ 4 has a small specific surface area. The photocatalytic activity is low due to the disadvantages of easy recombination of photogenerated carriers and low utilization of solar energy. Therefore, the aim of this paper is to optimize the photocatalytic performance of g-C _ 3N _ 4 by solving the above mentioned shortcomings of bulk phase g-C _ 3N _ 4. The main results are as follows: 1. In argon atmosphere, Ultrathin carbon nitride UGCNs were prepared by thermal stripping phase g-C3NAP4 method. The structure, morphology, specific surface area and optoelectronic properties of the samples were characterized by various methods. The photocatalytic reaction mechanism of the sample UGCN was also discussed. Compared with the bulk g-C _ s _ 3N _ 4, the specific surface area of the sample UGCN increased from 58.5 m ~ (-2) g ~ (-1) to 131.2 m ~ (2) g ~ (-1), and the visible light absorption was enhanced. The kinetic rate constant of UGCN photocatalytic degradation of Rhodamine (RhB) was 6.1 times of that of bulk g-C _ 3N _ s _ 4, and at the same time, The hydrogen production rate of g-C _ 3N _ 4 is twice as high as that of bulk phase g-C _ 3N _ 4. The surface properties of g-C _ 3N _ 4 modified by plasma treatment are optimized to optimize its photocatalytic properties. The effects of plasma treatment on the surface properties of the samples are investigated by various test methods. The mechanism of photocatalytic reaction of the modified g-C3Nder4 was discussed. Compared with the bulk g-C3N4, the modified g-C3N4 increased its hydrophilicity by introducing the hydrophilic functional group -OH- COOH. under visible light irradiation, the modified g-C3N4 increased its hydrophilicity. The degradation rate of the modified g-C _ 3N _ 4 RhB is twice as high as that of the bulk g-C _ 3N _ 3N _ 4. This method provides a new way of thinking for further optimizing the photocatalytic activity. A new type of g-C _ 3N _ 3N _ 4 / CoO composite was prepared by one-step calcination. Method for the structure of the sample, The morphology, specific surface area and optoelectronic properties were characterized, and the photocatalytic reaction mechanism of g-C _ 3N _ 3N _ 4 / CoO composite was discussed. The experimental data showed that the photocatalytic activity of g-C _ 3N _ 3N _ 3N _ 3N _ 3N _ 3N _ 3N _ (4) / CoO-0.5 wt% composite was the highest under visible light irradiation. The hydrogen production rate of the composite is three times that of pure g-C _ S _ 3N _ 4. G-C _ 3N _ 3N _ 4 / CoO composite has significantly improved photocatalytic performance mainly due to the matching of the energy band structure in the g-C _ 3N _ 3N _ 4 / CoO heterojunction, which leads to the enhancement of the optical absorption in the visible region and the improvement of the efficiency of photo-generated carrier separation.
【学位授予单位】：天津理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36

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