卤代氨基苯腈共聚合改性氮化碳光催化剂的合成及其光解水制氢

发布时间：2018-03-10 05:26

本文选题：g-C_3N_4　切入点：卤代氨基苯腈　出处：《郑州大学》2017年硕士论文　论文类型：学位论文

【摘要】：自2009年石墨相氮化碳g-C_3N_4首先被Wang等人作为光催化剂用于光解水制氢以来,作为可见光驱动的催化剂,g-C_3N_4引起了众多研究者的兴趣。g-C_3N_4作为非金属光催化剂具有诸多优点,如合适能带结构、易修饰、廉价等。但是g-C_3N_4光吸收范围窄、光电效率低等缺点仍然制约着其光催化性能的提高。针对g-C_3N_4的这些缺陷,本文主要从形貌调控、离子掺杂和共聚合改性几个方面开展工作,对g-C_3N_4进行改性。利用XRD、FTIR、SEM、UV-Vis DRS等手段对改性材料进行结构性质表征,并通过光催化制氢性能测试评价改性材料的光催化活性。主要工作内容如下:(1)利用氨基和腈基的亲电/亲核加成反应,以卤代氨基苯腈为共聚单体,制备了卤代氨基苯腈共聚合改性的氮化碳材料:F-CN、Cl-CN、Br-CN和I-CN。表征分析发现,卤代氨基苯腈共聚合改性的g-C_3N_4保持了本体g-C_3N_4的基本化学结构与形貌特征,但改性材料的光电性能有所提升。I-CN的XPS图谱中发现I 3d峰证明了含碘基团接入氮化碳分子骨架中。在负载4wt%Pt、可见光的照射下,F-CN、Cl-CN、Br-CN、I-CN的光催化制氢效率分别为41.46μmol·h-1、49.12μmol·h-1、55.35μmol·h-1和84.15μmol·h-1。相较于本体g-C_3N_4的13.62μmol·h-1均有提高,且按照卤素原子序数的增加而提高。其中I-CN制氢效率约是g-C_3N_4的6.18倍。主要原因是I-CN功能基团电负性相较于本体g-C_3N_4最低,提高了光电效率。同时,碘离子也可能同时对g-C_3N_4进行离子掺杂改性,产生共聚合改性与离子掺杂的共同作用,提高了其催化活性。再者I-CN光电流大约为g-C_3N_4的2倍。(2)利用HS-40水溶性硅胶,对氮化碳进行形貌调控,制备多孔共聚合改性氮化碳材料:g-MCN、F-MCN、Cl-MCN、Br-MCN和I-MCN,表征分析发现多孔材料相对于g-C_3N_4光电性能进一步增强。在可见光照射下,多孔的卤代氨基苯腈共聚合改性g-C_3N_4制氢性能大幅度的提高,在负载4wt%Pt、可见光的照射下I-MCN样品产氢效率最高,可达到109.12μmol·h-1,高于未经模板造孔的样品I-CN的84.12μmol·h-1,约达到本体g-C_3N_4的8.3倍。这是因为在共聚合改性的基础上,I-MCN产生了孔结构,增加了比表面积。
[Abstract]:Since 2009, when graphite-phase carbon nitride g-C _ 3N _ 4 was first used by Wang and others as photocatalyst for the production of hydrogen by photolysis of water, it has attracted many researchers' interest. G-C _ 3N _ 4 has many advantages as a non-metallic photocatalyst. Such as suitable band structure, easy modification, low cost, etc. However, the disadvantages of g-C _ 3N _ 4, such as narrow optical absorption range and low photoelectric efficiency, still restrict the improvement of its photocatalytic performance. The modification of g-C _ 3N _ 4 was carried out in several aspects of ion doping and copolymerization modification. The structure and properties of the modified materials were characterized by means of XRD-FTIR, SEMI-UV-Vis DRS, etc. The photocatalytic activity of the modified materials was evaluated by photocatalytic hydrogen production performance test. The main work was as follows: 1) using the electrophilic / nucleophilic addition reaction of amino and nitrile groups, halogenated aminobenzonitrile was used as the copolymerization monomer. Carbon nitride modified by halogenated aminobenzonitrile was prepared. It was found that g-C _ 3N _ 4 modified by the copolymerization of halogenated aminobenzonitrile maintained the basic chemical structure and morphology of g-C _ 3N _ 4, which was modified by the copolymerization of halogenated aminobenzonitrile. However, the I 3D peak of the modified materials was found in the XPS spectra of the modified materials. It was proved that the iodide-containing group was inserted into the carbon nitride molecular skeleton. The photocatalytic hydrogen production efficiency of F-CNCCl-CN-CN-CN-CNI-CN was 41.46 渭 mol 路h-1h-19.12 渭 mol 路h-1h-55.35 渭 mol 路h-1 and 84.15 渭 mol 路h-1, respectively, under the irradiation of 4wt Pt.The results showed that the photocatalytic efficiency of the modified materials was 41.46 渭 mol 路h-1h-1h-1h-55.35 渭 mol 路h-1 and 84.15 渭 mol 路h-1, respectively. Compared with the noumenon g-C3Ns 4, the 13.62 渭 mol 路h-1 of the tipping-C _ 3Ns _ 4 was increased, The hydrogen production efficiency of I-CN is about 6.18 times that of g-C _ 3N _ 4. The main reason is that the electronegativity of I-CN functional group is lower than that of g-C _ 3N _ 4, which improves the photoelectric efficiency. It is also possible that iodide ion can also doping g-C _ S _ 3N _ 4, resulting in the co-effect of copolymerization modification and ion doping, which enhances its catalytic activity. Furthermore, the photocurrent of I-CN is about twice that of g-C _ S _ 3N _ 4) using HS-40 water-soluble silica gel. The morphology of carbon nitride was regulated and the porous copolymerization modified carbon nitride materials were prepared. The results of characterization analysis showed that the optoelectronic properties of the porous materials were further enhanced compared with those of g-C _ 3N _ 4. Under visible light irradiation, the porous materials were better than g-C _ 3N _ 4. The hydrogen production performance of g-C _ 3N _ 4 modified by porous halogenated aminobenzonitrile was greatly improved, and the hydrogen production efficiency of I-MCN sample was the highest under the irradiation of 4wt Ptand visible light. It can reach 109.12 渭 mol 路h-1, which is 84.12 渭 mol 路h-1 of I-CN, which is about 8.3 times that of bulk g-C3N4. This is due to the formation of pore structure and the increase of specific surface area of I-MCN on the basis of copolymerization modification.
【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ116.2;O643.36

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