Preparation And Photocatalysis Performance Of Graphitic Carbon Nitrides And Its Composites

Graphitic carbon nitrides?g-C₃N₄?has attracted increasing research interests in photocatalytic degradation of organic pollutants and photocatalytic hydrogen production from water because of its excellent properties such as good visible light response,chemical stability and metal-free.But as a single semiconductor material,the photocatalytic efficiency of g-C₃N₄ is relatively low because of the high recombination rate of photogenerated electron-hole pair.Moreover the surface area of untreated g-C₃N₄ is low,it will reduce the photocatalytic activity in a certain extent.In this paper,these aspects of g-C₃N₄ were modified in order to suppress the recombination of photogenerated electron-hole pair,extend the maximum absorption wavelength and increase the specific surface area.In this paper,the bulk g-C₃N₄ powder has been synthesized by directly heating organic at different temperatures,and then ultrasound with petroleum ether,ethanol,acetone,water.Last two kind of compound catalysts were synthesized by combinating g-C₃N₄ with InVO₄ and ZnO.Through various characterizations and photocatalytic experiments,we have investigated the effects of calcination temperature,pH value of solution,semiconductor recombination,solvent ultrasound treatment on catalytic activity.Photocatalytic experiments and the characterizations of X-ray diffraction?XRD?,N2-adsorption?BET?,Ultraviolet-visible spectroscopy?UV-vis?show that : the sample obtained form melamine at 520? exhibits highest photocatalytic activity.When InVO₄ doped with 20wt%,g-C₃N₄/InVO₄ has the best photocatalytic activity based on the degradation of RhB,and the degradation rate reached98% after 3h visible-light irradiation.Its first-order reaction rate constant increased by 164%compared with pure g-C₃N₄.When ZnO doped with 6wt%,g-C₃N₄/ZnO has the best photocatalytic activity,and the degradation rate reached 99% after 3h visible-light irradiation,increased by 16% and 600% compared with pure g-C₃N₄ and pure ZnO were.The specific surface area of sample obtained by treated with petroleum ether reached 25.27m2/g,improved by 44% compared with untreated g-C₃N₄?17.53m2/g?.The degradation rate of RhB reached90% after 40 min visible-light irradiation,the catalytic efficiency improved by nearly 200%compared with pure g-C₃N₄.Its first-order reaction rate constant increased by 166% compared with untreated g-C₃N₄.