g-C_3N_4/g-C_3N_4异质结结构的制备及其光催化性能

Construction of g-C_3N_4/g-C_3N_4 heterojunction for enhanced visible-light photocatalysis

采用简单的热分解法,分别以硫脲、尿素及硫脲和尿素混合物等为原料,制备了三种具有不同能带结构的石墨相氮化碳(g-C_3N_4),并使用XRD、AFM、SEM、UV-vis等测试方法对所制备样品的晶相结构、形貌、以及光吸收能力等进行了表征,同时研究了不同能带结构的样品对甲基橙的光降解性能.结果表明:制备出的三种样品均是以三嗪环为基本结构单元的片层状化合物.其中,以硫脲和尿素混合物为原料制备出的g-C_3N_4/g-C_3N_4异质结厚度为1.05nm,禁带宽度为2.75eV,其对甲基橙的降解效率高于分别以硫脲、尿素为原料制备的gC_3N_4,这是因为制备出的g-C_3N_4/g-C_3N_4异质结结构,促进了电荷的有效分离和传输,提高了可见光光催化活性.

The present work developed a facile in site thermo polymerization method to construct g-C3N4,g-C3N4 samples were prepared from urea,thiourea and molecular composite precursors of urea and thiourea.The as-prepared samples were characterized by XRD,AFM,SEM,UV-vis for crystal structure,morphology and absorption ability of visible light.The photocatalytic activity was taken out by the degradation of MO solution.We discussed that the different band structure of g-C3N4 synthesized by different precursors.This results showed that the three kinds of samples have the same crystal structure,they all demonstrate s-Triazines units interlayer structure.The thickness of g-C3N4/g-C3N4 is 1.05 nm and the band gap energies of g-C3N4/g-C3N4 is 2.75 eV,g-C3N4/g-C3N4 heterojunction possess excellent photocatalytic activity than the single phase g-C3N4（thiourea）and g-C3N4（urea）under visible light.A g-C3N4/g-C3N4 heterojunction promote the separation and transfer of charge and enhance visible light photocatalytic activity.