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加热温度对尿素水溶液制备类石墨相氮化碳的影响及其机理
作者:张华森 李喜宝 冯志军 黄军同 卢金山 
单位:南昌航空大学材料科学与工程学院 南昌 330063 
关键词:类石墨 石墨相氮化碳 水中裂解 尿素 光催化 
分类号:O643.3
出版年,卷(期):页码:2018,46(2):0-0
DOI:
摘要:

石墨相氮化碳(g-C3N4)由于其优异的化学稳定性和独特的电子能带结构被认为是一种廉价且极具潜力的光催化剂,然而传统方法制备的g-C3N4存在比表面积小、光生电子–空穴复合严重及剥离效率低等问题。采用尿素溶于一定量的水中,通过控制一定的升温速率及加热温度制备性能优异的g-C3N4。结果表明,在水中450~500 ℃裂解尿素可获得疏松多孔、类石墨相的g-C3N4纳米片,在500 ℃时获得的g-C3N4具有较多的纳米孔隙及较大的比表面积;550 ℃时孔隙消失,且g-C3N4的带隙能随着加热温度升高逐渐降低。光催化结果表明,随水中裂解尿素温度升高,制备的g-C3N4在可见光下对罗丹明B的降解率先增大后减小,500 ℃时降解率最高,达到75.5%,且明显好于500 ℃时直接加热尿素制备g-C3N4的降解率(24.1%)。多孔、少层且高比表面积的类石墨烯微观结构是500 ℃下获得多孔g-C3N4样品较高的光催化活性的主要原因,h+和·O2–是参与降解反应的主要活性基团。

Graphitic carbon nitride (g-C3N4) is considered as an inexpensive and promising photocatalyst due to its excellent chemical stability and unique electronic band structure. However, g-C3N4 prepared by conventional method has some problems like small specific surface area, serious recombination of photogenerated electron hole and low stripping efficiency. Urea was dissolved in a certain amount of water, and g-C3N4 with excellent properties was prepared by controlling a certain heating rate and temperature. The results show that porous and graphite-like g-C3N4 nanosheet with little layer can be obtained via the pyrolysis of urea in water at 450–500 ℃. The g-C3N4 obtained at 500 ℃ has the maximum nanometer pore volume and specific surface area. The pores disappear at 550 ℃ and the band gap of g-C3N4 decreases gradually with the increase of heating temperature. The photocatalytic results show that the degradation of rhodamine B of g-C3N4 firstly increases and then decreases in the visible light with the increase of heating temperature of urea in water. The degradation rate is 75.5% at 500 ℃, which is greater than that of g-C3N4 prepared by direct heating of urea at 500 ℃ (24.1%).

基金项目:
江西省自然科学基金(20161BAB206111);南昌航空大学研究生创新专项基金项目(YC2016023)。
作者简介:
张华森(1992—),男,硕士研究生。
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