类石墨烯相氮化碳的制备和改性以及光催化性能的研究

发布时间：2018-08-15 17:11

【摘要】：在当前经济社会快速发展的大环境下,随着传统碳氢化石燃料日渐枯竭,人类社会在不久的未来将面临着严重的能源危机。随着能源危机的日益严重,环境污染问题也逐渐的突显出来,尤其是水污染问题又显得尤为突出。能源危机和环境污染也是目前世界各国普遍面临和亟待解决的问题,如果不加以改善,人类社会的长久发展将无法实现。对于水体中那些难降解的有机污染物,尤其是持久性有机污染物,采用传统的处理方法已很难将其彻底的去除。因此,如果能开发一种新的技术,这种技术能够将水体中的难降解有机污染物去除的同时获得新能源(如氢气),从而实现污染治理与能源化同步,这样不仅有利于解决环境污染的问题,同时也有利于缓解能源危机。因此,本论文系统研究了N-GQDs/CN-U和CDs/CdS/CNU复合半导体光催化剂在光催化产氢和有污染物去除以及同步实现等方面的研究和应用。论文中采用煅烧法合成由不同前驱体(尿素、双氰胺和三聚氰胺)煅烧所得到的g-C_3N_4催化剂,系统地研究了不同形貌、聚合方式和质子化程度等因素对光催化效果的影响,在此基础上引入不同比例的具有良好光吸收和上转换效应的氮掺杂的石墨烯量子点(N-GQDs)。实验结果表明,N-GQDs能够很好的增强光催化剂的催化效果,当N-GQDs的负载量(wt%)为15%时光催化效果最佳,在可将光下,复合催化剂15N-CNU的光催化产氢速率是单纯g-C_3N_4的2.16倍,产氢速率可达2.18 mmol·g-1·h-1,其相应的量子效率为5.25%。另外,本论文拟将具有良好光催化降解有机污染物的催化剂与光催化分解水产氢的催化剂进行结合,形成异质结,从而构建具有高效、稳定的有机污染物光催化降解和同步分解水产氢的光催化体系,最终实现有机废水的矿化去除及同步能源化。我们采用溶剂热法合成不同比例CdS量子点负载的CdS/CNU异质结催化剂,此催化剂能够实现光催化降解对硝基苯酚并同时实现光催化析氢反应。在此基础上,我们将具有良好光吸收的CDs引入,合成CDs/CdS/CNU三元复合光催化剂。实验结果表明,当CDs的负载量(wt%)为3%时,其光催化效果最佳,对硝基苯酚的去除率达到98%,产氢速率可达25μmol·h-1·g-1。此外,也系统的研究了不同污染物的光降解与光催化产氢之间的协同-抑制的构效关系。
[Abstract]:With the rapid development of economy and society, with the depletion of traditional hydrocarbon fossil fuels, human society will face a serious energy crisis in the near future. With the increasingly serious energy crisis, environmental pollution is gradually highlighted, especially water pollution. Energy crisis and environmental pollution are also the problems that all countries in the world are facing and need to be solved. If they are not improved, the long-term development of human society will not be realized. For those organic pollutants, especially persistent organic pollutants, which are difficult to be degraded in water, it is difficult to remove them thoroughly by traditional treatment methods. Therefore, if a new technology can be developed that can simultaneously remove refractory organic pollutants from water and obtain new energy sources (such as hydrogen), it will synchronize pollution control with energy conversion. This not only helps to solve the problem of environmental pollution, but also helps to alleviate the energy crisis. Therefore, the research and application of N-GQDs/CN-U and CDs/CdS/CNU composite semiconductor photocatalysts in hydrogen production, pollutant removal and synchronization have been systematically studied in this paper. In this paper, the g-C_3N_4 catalysts obtained from the calcination of different precursors (urea, dicyandiamide and melamine) were synthesized by calcination method. The effects of different morphology, polymerization methods and degree of protonation on the photocatalytic effect were systematically studied. On this basis, different proportions of nitrogen-doped graphene quantum dots (N-GQDs) with good optical absorption and up-conversion effects were introduced. The experimental results show that N-GQDs can enhance the photocatalytic effect of photocatalyst. When the amount of N-GQDs loading is 15%, the photocatalytic efficiency of 15N-CNU is 2.16 times as high as that of g-C_3N_4. The hydrogen production rate can reach 2.18 mmol g-1 h-1, and the corresponding quantum efficiency is 5.25. In addition, the catalyst with good photocatalytic degradation of organic pollutants and the catalyst for photocatalytic decomposition of aquatic hydrogen will be combined to form heterojunction. A stable photocatalytic system for photocatalytic degradation and simultaneous decomposition of aquatic hydrogen was used to realize the mineralization and simultaneous energy removal of organic wastewater. CdS/CNU heterojunction catalysts supported on different CdS quantum dots were synthesized by solvothermal method. The photocatalytic degradation of p-nitrophenol and photocatalytic hydrogen evolution were achieved by this catalyst. On this basis, CDs with good light absorption was introduced to synthesize CDs/CdS/CNU ternary composite photocatalyst. The experimental results show that the photocatalytic effect of CDs is the best when the loading amount of CDs is 3%, the removal rate of p-nitrophenol reaches 98 and the hydrogen production rate can reach 25 渭 mol h-1 g-1. In addition, the synergistic structure-activity relationship between photodegradation of different pollutants and photocatalytic hydrogen production was also systematically studied.
【学位授予单位】：南昌航空大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O613.71;O643.36

【相似文献】