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采用溶胶-凝胶法及焙烧处理制备了g-C_3N_4/TiO_2复合光催化材料,利用多种分析手段进行了结构与性能表征。研究表明,在n(N):n(Ti)=3.5、焙烧温度580℃条件下制备的样品光催化降解染料亚甲基蓝,在紫外光与可见光照射下的催化反应速率常数分别是纯TiO_2的1.2倍、纯g-C_3N_4的3.1倍。通过XPS和HR-TEM分析可知,凝胶中三聚氰胺的热解使N和C原子扩散到TiO_2晶格中,形成了g-C_3N_4-TiO_2异质结。紫外-可见漫反射分析显示,g-C_3N_4掺杂使TiO_2光吸收范围扩展至可见光区,光催化活性提高的主要原因归结于:形成g-TiO_2-TiO_2异质结和TiO_2的锐钛矿与金红石特殊相界的协同作用。
The g-C 3 N 4 / TiO 2 composite photocatalyst was prepared by sol-gel method and calcination. The structure and properties of the composite were characterized by various analytical methods. The results show that the photocatalytic degradation rate of methylene blue in the sample prepared at n (N): n (Ti) = 3.5 and calcination temperature 580 ℃ is 1.2 times that of pure TiO_2 under ultraviolet light and visible light irradiation respectively 3.1 times that of pure g-C_3N_4. By XPS and HR-TEM analysis, it can be seen that pyrolysis of melamine in the gel diffused N and C atoms into the lattice of TiO 2 to form a g-C 3 N 4 -TiO 2 heterojunction. UV-visible diffuse reflectance analysis showed that the main reason for the increase of photocatalytic activity of g-C_3N_4 doped TiO 2 is that the formation of g-TiO_2-TiO_2 heterojunction and TiO_2 from anatase to rutile Special phase of the synergy.