三维多孔g-C3N4/Cu2O光催化材料的结构调控及光生电荷传输行为研究

Upon environmental pollution, it is of scientific significance and practical values to develop efficient and stable photocatalysts driven by visible light. Recently, as a promising metal-free photocatalyst, graphitic carbon nitride (g-C3N4) has drawn great interest owing to a bandgap of 2.7eV working in visible spectral region. However, the intrinsic drawbacks of g-C3N4, in particular the poor mass diffusion and fast charge recombination are not well addressed. Moreover, almost all studies reported thus far have been focused on g-C3N4 in the powder form that suffers from a complicated recovery step during the photocatalytic process, setting a hurdle for the real applications. Herein, we report synthesis of a macroscopic 3D porous g-C3N4 by one-step thermal polymerization of urea inside the framework of cheap melamine sponge template, which is free of any other functionalizing or crosslinking agents. Then coupling g-C3N4 with Cu2O quantum dot to form p-n heterojunction, which can promote the light carrier transfer and thus improve the light quantum efficiency of catalyst. Futhermore, the macroscopic 3D g-C3N4/Cu2O photocatalyst with better recovery properties for the industrial and practical applications.

研制和开发高效、稳定的可见光催化剂对解决环境污染具有重要的科学意义和实用价值。近年，石墨相氮化碳（g-C3N4）因较窄的能带间隙使其具有可见光响应特性，已成为一种极具应用潜力的半导体光催化材料。然而，块体相g-C3N4材料光催化效果并不理想，主要是由于较差的传质动力学，光生电子和空穴容易复合，导致量子效率较低。此外，目前已见报道的g-C3N4基光催化剂大多数均为纳米颗粒的悬浮体系，在实际水体处理中不仅分离困难、难以回收再利用。本项目拟以廉价易得的三聚氰胺泡沫作为前驱体及模板，尿素作为助剂，通过一步热缩聚法得到三维多孔g-C3N4骨架，在此基础上与窄带隙的Cu2O量子点复合形成p-n异质结，在可见光的激发下有望促进光激发电荷和空穴分离、迁移，从而提高量子效率。不仅如此，三维多孔的g-C3N4/Cu2O复合光催化剂还兼具易回收，可循环使用的优势，为其作为实用性环境功能材料提供理论和技术支持。

研制和开发高效、稳定的可见光催化剂对解决环境污染具有重要的科学意义和实用价值。近年，石墨相氮化碳（g-C3N4）因较窄的能带间隙使其具有可见光响应特性，已成为一种极具应用潜力的半导体光催化材料。然而，块体相g-C3N4材料光催化效果并不理想，主要是由于较差的传质动力学，光生电子和空穴容易复合，导致量子效率较低。本项目以廉价易得的三聚氰胺泡沫作为前驱体及模板，尿素作为助剂，通过一步热缩聚法得到三维多孔g-C3N4骨架，在此基础上与窄带隙的Cu2O量子点复合形成p-n异质结。与纯的g-C3N4相比，g-C3N4/Cu2O异质结在光催化效率和稳定性方面都有明显的提升，反应60min对甲基橙的去除率就达到100%。经过10次循环后，对MO的降解率仍可达到99%。通过表征分析, g-C3N4/Cu2O异质结界面结合紧密，从而促进光生载流子的有效分离，拓展了光响应范围，有效提升了量子效率和光的利用率，从而进一步提升了光催化性能。