Design,Preparation And Properties Of G-C₃N₄-Based Photocatalytic Materials

With the advancement of industrialization,the problem of ecological pollution is becoming increasingly serious,and environmental protection has gradually become an important subject for the sustainable development of mankind,which has attracted more and more researchers’attention.Currently,solar-driven photocatalysis is widely recognized as one of the best solutions to solve environmental problem.G-C₃N₄is a typical two-dimensional nonmetallic semiconductor photocatalytic material,which has the advantages of simple preparation process,stable physical and chemical properties,and rich raw materials.However,the photocatalytic activity of g-C₃N₄is limited by the high photogenerated electron-hole pair recombination efficiency and narrow visible light response range.As a result,the photocatalytic efficiency is still not high enough to meet the actual production requirements.In view of the shortcomings of g-C₃N₄,this paper designed and prepared two new composite photocatalysts by constructing heterojunction and adjusting the band structure to improve the visible-light photocatalytic performanceof g-C₃N₄.1.A novel g-C₃N₄-based ternary heterojunction was rationally designed and constructed by the in situ growth of Zn In₂S₄nanosheets and Cd S nanoparticles onto the g-C₃N₄nanosheets using a facile two-step oil-bath method.The results showed that the catalytic performance of ternary photocatalysis was better than that of two-component and one-component photocatalysis.Among them,Cd S/Zn In₂S₄/g-C₃N₄-0.2 showed the best photocatalytic performance.The photocatalytic degradation rate of Rh B could reach 96%,which was about 27.42 and1.17 times than that of pure g-C₃N₄and Zn In₂S₄/g-C₃N₄-0.7 binary composite.The excellent photocatalytic activity of the Cd S/Zn In₂S₄/g-C₃N₄ternary heterojunction could be attributed to the synergistic interaction of Cd S,Zn In₂S₄and g-C₃N₄,which not only broadened the range of visible light absorption,but also improved the separation and migration efficiency,thus enhancing the visible light photocatalytic performance of g-C₃N₄.2.G-C₃N₄doped with pyromellitic diimide（PDI）,namely g-C₃N₄/PDI,was prepared by a facile thermal condensation.The Zn In₂S₄nanosheets were further grown on the g-C₃N₄/PDI nanosheets through an oil-bath method to construct the g-C₃N₄/PDI@Zn In₂S₄heterojunctions.The results showed that both g-C₃N₄/PDI and g-C₃N₄/PDI@Zn In₂S₄showed better visible light photocatalytic performance than g-C₃N₄due to the broadened visible light absorption range and the improved separation and migration efficiencies of photo-induced electron-hole pairs.The photocatalytic degradation efficiency of g-C₃N₄/PDI and g-C₃N₄/PDI@Zn In₂S₄for Rh B were 22%and 80%,respectively,which were about 4.77 and 17.13 times that of g-C₃N₄.