石墨相氮化碳的制备、改性及其光催化性能研究

发布时间：2018-01-12 19:36

本文关键词：石墨相氮化碳的制备、改性及其光催化性能研究　出处：《青岛科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：由于普通方法制备的石墨相氮化碳(g-C3N4)材料存在比表面积大、结晶度低、光生电子-空穴对复合率高等弊病,严重阻碍了其在光催化领域的应用发展。针对这些问题,本文主要通过两个方面对g-C3N4光催化性能的提升进行了研究。第一,分别通过氧化刻蚀、Ag负载和机械球磨对g-C3N4进行改性,从而达到对其进行分散及提升量子利用效率的目的；第二,通过以尿素和三聚氰胺为混合前驱体,半封闭细口瓶作为反应容器,煅烧制得比表面积大、结晶程度高的g-C3N4纳米片。论文的具体研究内容及成果如下：(1)首先通过在550℃热缩聚三聚氰胺的方法制备g-C3N4块体材料,然后以双氧水为氧化剂,乙酸和浓硫酸为分散及辅助氧化剂,对g-C3N4块体材料进行氧化刻蚀改性。本文系统研究了双氧水加入量、乙酸加入量及温度对氧化刻蚀后样品光催化性能的影响。实验结果表明,当g-C3N4为1g、浓H2SO420ml、乙酸20ml、H2O2 1ml时,经氧化刻蚀处理的g-C3N4光催化性能最佳,10 mg.L-1的甲基橙溶液经模拟日光辐照1h,降解率可以达到98.2%,并且随着温度的升高,氧化刻蚀后样品的催化性能越好,但收率越低。XRD结果表明,氧化刻蚀可以在一定程度去除g-C3N4样品中部分非晶区域,从而使样品总体结晶性有所升高；IR和EDS表征结果表明氧化刻蚀可以在样品中掺入少量氧元素；TEM和SEM结果表明,氧化刻蚀改性可以大大提升g-C3N4样品的分散性能。高结晶性、高分散性以及氧元素的掺入是样品光催化性能提升的根本原因。(2)以550℃热缩聚三聚氰胺的方法制备g-C3N4块体材料,通过超声粉碎得到g-C3N4纳米片,然后将g-C3N4纳米片加入AgNO3溶液中,光照条件下使AgNO3还原制备Ag/g-C3N4复合纳米片。文章研究了不同理论质量百分数Ag负载对g-C3N4纳米片光催化性能的影响,并对Ag/g-C3N4复合纳米片进行XRD、 IR、XPS、TEM、UV-vis、PL表征。结果表明,当Ag在Ag/g-C3N4复合纳米片中的理论质量百分比为8%时,其光催化性能最佳,10 mg·L-1的罗丹明B溶液经模拟日光辐照30 min,降解率可以达到92.7%。经分析认为,Ag/g-C3N4复合纳米片优异的光催化性能可归功于Ag纳米颗粒的表面等离子共振和Ag纳米粒子与g-C3N4纳米片界面处有效的光生载流子的分离。(3)以550℃热缩聚三聚氰胺的方法制备g-C3N4块体材料,通过机械球磨法对g-C3N4进行改性。本文系统研究了球磨时间为12 h、1天、3天、5天的样品的光催化性能,并对球磨改性后样品进行XRD、TEM、UV-vis表征。结果表明,随着球磨改性时间的延长,样品的光催化性能逐次变好。经分析认为,球磨改性可以大大提升g-C3N4的分散性,降低其厚度,从而提供更多的光催化反应活性位,提升样品光催化性能。(4)将尿素和三聚氰胺研磨混合并作为制备g-C3N4纳米片的混合前驱体,使用细口瓶作为反应容器,并用铝箔纸制备的塞子封闭细口瓶,然后在程序升温条件下煅烧制备g-C3N4纳米片。本文系统的研究了尿素与三聚氰胺的质量配比、煅烧时间、温度和反应容器密闭性对制备g-C3N4纳米片可见光下光催化降解罗丹明B性能的影响,并对部分样品进行了光催化降解亚甲基蓝的实验研究。通过XRD、TEM、UV-vis、PL、阻抗对g-C3N4纳米片样品进行表征,结果表明,当尿素：三聚氰胺质量比为5：2、煅烧时间为6 h、煅烧温度为575℃时,制备的g-C3N4纳米片具有高结晶性、高分散性、低电阻的优异性能,光催化性能最佳,并且反应容器密闭性越好,样品的催化性能也随之提升。通过对比罗丹明B和亚甲基蓝的降解结果得出,g-C3N4纳米片对具有光敏化效应的罗丹明B具有更高的催化降解活性。
[Abstract]:Because of the common methods of preparation of graphite carbon nitride (g-C3N4) materials have large surface area, low crystallinity, photogenerated electron hole recombination rate higher ills, seriously hindered the development of applications in the field of photocatalysis. To solve these problems, this paper mainly through the two aspects to enhance the photocatalytic performance of g-C3N4 was studied. First, respectively by oxidation etching, modification of g-C3N4 Ag load and mechanical milling, in order to disperse and enhance the quantum efficiency of second; by urea and melamine as the mixed precursor, semi closed narrow mouth bottles as the reaction vessel, calcined with large surface area g-C3N4, nano high degree of crystallinity. The specific research contents and results of this paper are as follows: (1) firstly by means of poly melamine in 550 degrees Celsius heat shrinkable preparation of g-C3N4 bulk material, then using hydrogen peroxide as oxidant. B Acid and concentrated sulfuric acid as dispersing and auxiliary oxidant of g-C3N4 bulk material by oxidation etching modification. This paper systematically studies the hydrogen peroxide dosage, acetic acid amount and temperature on the photocatalytic performance of the sample after oxidation etching. The experimental results show that when g-C3N4 is 1g, H2SO420ml concentration, acetic acid 20ml, H2O2 1ml and by oxidation etching processing g-C3N4 the best photocatalytic performance, 10 mg.L-1 methyl orange solution by simulated solar irradiation 1H, the degradation rate can reach 98.2%, and with the increase of temperature, the better the catalytic performance of the sample after oxidation etching, but the yield is low.XRD results show that the oxidation etching can remove part of the amorphous region of g-C3N4 in the sample to a certain extent, so that the overall sample crystallinity increased; IR and EDS. The results showed that oxidation etching in the sample can be mixed with a small amount of oxygen; TEM and SEM results showed that the modified oxidation etching Greatly enhance the dispersion properties of g-C3N4 samples. The high crystallinity, high dispersibility and oxygen incorporation is the fundamental reason to enhance the photocatalytic performance of the sample preparation method. (2) to 550 degrees polymerization of melamine by g-C3N4 bulk materials, nano g-C3N4 obtained by sonication, then adding g-C3N4 nano sheet AgNO3 solution, light conditions make AgNO3 preparation of Ag/g-C3N4 nano composite film reduction method. The paper studies the theory of different concentrations of Ag load effect on the photocatalytic performance of nano g-C3N4, and XRD, Ag/g-C3N4 nano composite tablets IR, XPS, TEM, UV-vis, PL respectively. The results show that when the Ag in Ag/g-C3N4 in the theory of composite nano mass percentage is 8%, the best photocatalytic performance, Luo Danming B 10 mg - L-1 solution by simulated sunlight irradiation 30 min, the degradation rate can reach 92.7%. after analysis, Ag/g-C3N4 composite nano sheet excellent Separation and photocatalytic performance can be attributed to the surface plasmon resonance of Ag nanoparticles and Ag nanoparticles and nano g-C3N4 interface effective photocarrier. (3) method to 550 DEG C thermal condensation of melamine by g-C3N4 bulk materials, g-C3N4 was modified by mechanical milling method. This paper studies the milling time 12 h, 1 days, 3 days, 5 days of the photocatalytic performance of the sample, and XRD, mill on the modified samples TEM, UV-vis characterization. The results show that with increasing milling modification time, photocatalytic performance of successive samples better. After analysis that ball milling modification can greatly to enhance the dispersion of g-C3N4, reduce the thickness, thus providing the photocatalytic activity more, enhance the photocatalytic performance of the sample. (4) the urea and melamine mixing and grinding is used in the preparation of mixed precursors of g-C3N4 nanosheets, the use of narrow mouth bottles as a reaction container Device, and foil paper by plug closed flasks, then under the condition of temperature programmed calcination preparation of g-C3N4 nano sheet. This paper systematically studies the mass ratio of urea and melamine, calcination temperature and reaction time, the container closed preparation performance of B photocatalytic degradation of Luo Danming g-C3N4 nanosheets under visible light on system, and some of the samples were studied. The photocatalytic degradation of methylene blue by XRD, TEM, UV-vis, PL, g-C3N4 nano film samples were characterized, impedance results show that when the urea melamine quality ratio of 5:2, calcination time was 6 h, the calcination temperature is 575 degrees centigrade, nano g-C3N4 the preparation has a high crystallinity, high dispersion, excellent performance and low resistance, the best photocatalytic performance, and the reaction vessel sealing better, catalytic properties of the samples are increasing. Through the comparison of Luo Danming B and degradation of methylene blue. It is concluded that the g-C3N4 nanoscale has a higher catalytic activity for the photosensitization of Luo Danming B.

【学位授予单位】：青岛科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O643.36;X703

【相似文献】