Morphology Regulation And Photocatalytic Performance Of Graphite Phase Carbon Nitride Modified By Nonmetallic Salt

With its special advantages,photocatalysis technology provides important support for human to solve environmental problems and alleviating energy poverty.Graphitic phase carbon nitride（g-C₃N₄）is a semiconductor polymer.Its advantages involve easy preparation and response to visible light.Limited by the small specific surface area of g-C₃N₄,its practical application is hindered.In this paper,modified samples were prepared through various treatment methods,and the photosynthesis properties of modified samples were investigated by various description methods.The conclusion is as follows:（1）Using melamine and phosphoric acid as raw materials,then adding different amounts of phosphoric acid in proportion,and the modified graphite phase carbon nitride was obtained through calcination,while the pure melamine was directly calcined as the control group.Degradation experiments showed that the degradation rate constant k of P-CN3 was 508%higher than that of untreated precursor samples.With the help of phosphoric acid,the modified sample has stronger REDOX capacity.（2）Using melamine and sodium phosphate as raw materials,the precursor was treated by hydrothermal and direct mixing,and the modified graphite phase carbon nitride was obtained by calcination.By means of characterization,it is found that the sample prepared by hydrothermal treatment of precursor has wider gap band,0.15e V more than the sample directly mixed and calcined.Degradation experiments showed that the degradation rate constantk of SP-CN2 samples for methyl blue was 237%higher than that of HP-CN2.The degradation rate constant k of SP-CN1 was increased by 95.2%compared with HP-CN2.It shows that the precursor has stronger photocatalytic ability after heat treatment.（3）On the basis of a certain amount of melamine and ammonium sulfate,adding different amounts of sulfuric acid,stirring into paste to prepare four kinds of precursors,through calcination to obtain modified graphite phase carbon nitride.The UV-VIS diffuse reflection spectrum showed that SC-CN1,whose precursor consisted of melamine and ammonium sulfate plus 0.5ml sulfuric acid,had a band gap of 0.12e V compared with the sample without sulfuric acid.The degradation rate of methyl blue solution of SC-CN1 was increased by 62%compared with SC-CN3,and the degradation rate constant k of Rhodamine B was increased by 50.8%compared with SC-CN3,indicating that the photocatalytic activity would decrease with the increase of sulfuric acid.（4）The precursor composed of melamine,sodium phosphate and ammonium sulfate was prepared by different treatment methods,and then the melamine,sodium phosphate and trithiocyanuric acid were ground evenly before being used,and the modified graphite phase carbon nitride was obtained by calcination.The degradation rate constant k of PS-CN4 for Rhodamine B was increased by 50%compared with PS-CN2.The results indicated that the sample with ammonium sulfate had better degradation effect on methyl blue,and the sample with tripoly-thiocyanate had better degradation effect on Rhodamine B.