Yang Qian, Lin Wensong, Duan Zhichang, Xu Sen, Chen Junnan, Mai Xin
School of Materials Engineering, Shanghai University of Engineering Science, Shanghai, People's Republic of China.
Environ Technol. 2023 Mar;44(8):1156-1168. doi: 10.1080/09593330.2021.1996467. Epub 2021 Nov 13.
In this work, g-CN/ZIF-8 heterojunction photocatalysts were synthesised by the process by which the metal-organic framework ZIF-8 nanoparticles were grown onto the g-CN layer in situ. Bismuth element was doped into the as-prepared g-CN/ZIF-8 material and a new type of Bi@g-CN/ZIF-8 composite photocatalysts was manufactured, in which the doping element acts in adjusting the bandgap in the photocatalysts. The prepared photocatalysts were characterised by XRD, FESEM, TEM, FTIR, XPS, UV-VIS DRS, photoluminescence and photo-electrochemical experiments. The results show that the ZIF-8 nanoparticles grown in situ were well-formed onto the g-CN layer, and bismuth was evenly doped into the gaps of the g-CN/ZIF-8 framework. The degradation rate of methylene blue by CNZ-1.5(Bi)-12, which was a photocatalyst composed of 12% Bi-doped with g-CN/ZIF-8 material (the mass ratio of g-CN: ZIF-8 = 1:1.5), reached 86.6% under visible light irradiation within 60 min. The free radical scavenging experiment and electron spin resonance spectroscopy showed that was the main active substance. Bismuth doping into the photocatalytic system promotes the excitation of electrons from the valence band to the conduction band and provides a good channel for the transmission of photogenerated carriers as well. It is achieved that intensive visible light absorption, the enhanced separation efficiency of photogenerated carriers, and excellent thermal stability and high recyclability in the novel composite photocatalyst, owing to the synergistic effect of the introduced bismuth with the heterostructure of g-CN/ZIF-8. Therefore, the synthesised Bi@g-CN/ZIF-8 heterojunction photocatalysts may be used as a good photocatalyst for purifying and degrading organic matter in sewage.
在本工作中，通过将金属有机框架ZIF-8纳米颗粒原位生长在g-CN层上的过程合成了g-CN/ZIF-8异质结光催化剂。将铋元素掺杂到所制备的g-CN/ZIF-8材料中，制备了一种新型的Bi@g-CN/ZIF-8复合光催化剂，其中掺杂元素起到调节光催化剂带隙的作用。通过XRD、FESEM、TEM、FTIR、XPS、UV-VIS DRS、光致发光和光电化学实验对所制备的光催化剂进行了表征。结果表明，原位生长的ZIF-8纳米颗粒在g-CN层上形成良好，铋均匀地掺杂到g-CN/ZIF-8框架的间隙中。由12%铋掺杂的g-CN/ZIF-8材料（g-CN与ZIF-8的质量比为1:1.5）组成的光催化剂CNZ-1.5(Bi)-12在可见光照射下60分钟内对亚甲基蓝的降解率达到86.6%。自由基清除实验和电子自旋共振光谱表明·OH是主要活性物质。铋掺杂到光催化体系中促进了电子从价带激发到导带，也为光生载流子的传输提供了良好的通道。由于引入的铋与g-CN/ZIF-8异质结构的协同作用，在新型复合光催化剂中实现了强烈的可见光吸收、增强的光生载流子分离效率以及优异的热稳定性和高可回收性。因此，所合成的Bi@g-CN/ZIF-8异质结光催化剂可作为一种良好的光催化剂用于净化和降解污水中的有机物。
