一步法制备氮化碳复合材料及其光催化降解有机污染物性能

One-step synthesis of carbon nitride composite materials and its photocatalytic degradation of organic pollutants

光催化技术是解决能源短缺和治理环境污染最有前途的技术。氮化碳作为一种新型绿色无污染半导体材料备受青睐。纯氮化碳量子效率低,易产生光生载流子复合现象,在可见光照射下的光催化性能受到限制,可采用贵金属修饰、离子掺杂及异质结构建等对其进行改性。以三聚氰胺、碘化钾、五水合硝酸铋为原料,高温520℃焙烧三聚氰胺制备石墨相氮化碳(g-C_(3)N_(4)),通过一步共沉淀法使BiOI在生成的过程中原位生长在g-C_(3)N_(4)上,制备n-n型g-C_(3)N_(4)/BiOI异质结光催化剂。异质结相界面的出现增加了光生载流子的分离效率,比普通石墨相氮化碳具有更好的光催化性能。降解模拟污染物甲基橙(MO)、亚甲基蓝(MB)、罗丹明B(RhB)结果表明,当n(g-C_(3)N_(4))∶n(BiOI)=1∶1时,催化剂表现出最好的光催化活性,MO降解率几乎100%,MB降解率98%,RhB降解率80%,降解速率常数分别是纯相g-C_(3)N_(4)的385倍、24.3倍和2.5倍。

Photocatalysis technology is the most promising technology to solve energy shortage and control environmental pollution.Carbon nitride is favored in the industry as a new type of green pollution-free semiconductor material.However,pure carbon nitride has low quantum efficiency and high photo-gener-ated carrier recombination rate,which limits the photocatalytic performance under visible light irradiation.The frequently-used modification methods include noble metal modification,ion doping and heterostructure construction.In this paper,melamine,potassium iodide,and bismuth nitrate pentahydrate are used as raw materials.The graphite phase carbon nitride(g-C_(3)N_(4))is prepared by calcining melamine at a high temperature of 520℃.The n-n type g-C_(3)N_(4)/BiOI heterojunction photocatalyst was prepared by one-step co-precipitation method.The heterojunction interface greatly increases the separation efficiency of photogenerated carriers,resulting in better photocatalytic performance.Photodegradation of methyl orange(MO),methylene blue(MB)and Rhodamine B(RhB)showed that the catalyst with molar ratio of g-C_(3)N_(4)∶BiOI=1∶1 had the best photocatalytic activity.The degradation efficiency of MO,MB and RhB was almost 100%,98%and 80%,respectively.The apparent reaction rate constants were 385 times,24.3 times and 2.5 times of pure g-C_(3)N_(4).