Preparation And Properties Study Of Photocatalytic Materials Based On Porous G-C₃N₄

Photocatalytic technology using green,renewable solar energy effectively has been demonstrated to be one of the most promising methods to alleviate,and even solve,both the world energy crisis and environmental pollution.Among the many photocatalysts,graphite-like carbon nitride?g-C₃N₄?,with the narrow band gap?2.5².9 eV?and stable chemical properties,is widely used in the field of photocatalysis.However,the g-C₃N₄particle prepared by the traditional thermal polymerization method has some disadvantages,such as large g-C₃N₄ particle size,low specific surface area,high photoelectron-hole recombination rate,slow photo-carrier transport and low adsorption capacity.In response to the above problems,this paper carried out the following research:main research results have been obtained are described as following.?1?Porous g-C₃N₄?pg-C₃N₄?has been successfully fabricated by thermal polymerization method using SiO₂ nanosphere as hard template and dicyandiamide as the precursor.The structure,morphology and porous structure of pg-C₃N₄ samples were characterized by X-ray diffraction,scanning electron microscopy,transmission electron microscope and N₂ adsorption/desorption experiments.The results show that the prepared pg-C₃N₄ has a porous structure and a higher specific surface area.When the mass ratio of dicyandiamide and SiO₂ nanospheres is 1.5:1,the BET surface area of pg-C₃N₄?DICY:SiO₂=1.5:1?is 147.82 m²/g,which is 8 times than that of the bulk g-C₃N₄.The photocatalytic degradation of Rhodamine B?RhB?was carried out under the same conditions.The degradation rate of RhB with bulk g-C₃N₄ was only 33%at 60min,while pg-C₃N₄?DICY:SiO₂=1.5:1?degradation rate of RhB was 81%,which was 2.38 times that of bulk g-C₃N₄.It shows that the increase of pg-C₃N₄ specific surface area could effectively improve its photocatalytic performance.?2?Ag nanoparticles deposited pg-C₃N₄?Ag/pg-C₃N₄?was prepared by hydrothermal method and high-temperature calcinations method.The phase and the morphology of the sample were characterized by X-ray diffraction,scanning electron microscopy and transmission electron microscope.It was shown that Ag nanoparticles was deposited on the surface of pg-C₃N₄.N₂ adsorption/desorption experiments results show that the prepared Ag/pg-C₃N₄ has porous structure,the BET surface area of 10%Ag/pg-C₃N₄,20%Ag/pg-C₃N₄,30%Ag/pg-C₃N₄ is 68.94 m²/g,47.15 m²/g,and 43.61 m²/g,respectively.The results suggest that the specific surface area of Ag/pg-C₃N₄ decreases with the increase of Ag nanoparticles deposition.The photocatalytic degradation experiment was carried out with RhB as the degradation object under the same condition.The degradation rate of RhB by 10%Ag/pg-C₃N₄,20%Ag/pg-C₃N₄ and 30%Ag/pg-C₃N₄ was 86%,93%and 96%at60min,respectively.The results of photocatalytic experiment show that the deposition of Ag nanoparticle can effectively improve the photocatalytic performance of pg-C₃N₄,and the photocatalytic properties of Ag/pg-C₃N₄ gradually increase with the increase of Ag nanoparticle content.?3??-Fe₂O₃/pg-C₃N₄ composites catalysts were prepared by hydrothermal method and high-temperature calcinations method.The samples were characterized by X-ray diffraction analysis,scanning electron microscope and transmission electron microscope,the results show that?-Fe₂O₃ and pg-C₃N₄ has been composed.N₂ adsorption/desorption experiments results show that the prepared?-Fe₂O₃/pg-C₃N₄ has porous structure,the BET surface area of 10%?-Fe₂O₃/pg-C₃N₄,20%?-Fe₂O₃/pg-C₃N₄,30%?-Fe₂O₃/pg-C₃N₄ is123.05 m2/g,116.81 m2/g,109.65 m2/g,respectively.The results suggested that the specific surface area of?-Fe₂O₃/pg-C₃N₄ decreases with the increase of?-Fe₂O₃ content.The photocatalytic degradation experiment was carried out with RhB as the degradation object under the same condition.The degradation rate of RhB by 10%?-Fe₂O₃/pg-C₃N₄,20%?-Fe₂O₃/pg-C₃N₄,30%?-Fe₂O₃/pg-C₃N₄ was 84.02%,85.42%and 87.52%at 60min,respectively.The results of photocatalytic experiment show that?-Fe₂O₃ can effectively improve the photocatalytic performance of pg-C₃N₄,and the photocatalytic properties of?-Fe₂O₃/pg-C₃N₄ gradually increase with the increase of?-Fe₂O₃ content.