Design And Synthesis Of Graphitic Carbon Nitride Based On Atomic/Molecular Doping And Study Of Its Photocatalytic Properties

Semiconductor photocatalysis technology can directly convert solar energy into chemical energy and electrical energy,which is one of the important means to solve the future energy and environmental crisis.Among various semiconductor materials,graphitic carbon nitride(g-C3N4)has attracted much attention due to its high chemical stability,thermal stability,suitable band gap,and low cost and easy availability.However,synthetic methods and routes strongly affect the physical and chemical properties of materials.The g-C3N4 synthesized by the traditional thermal polymerization method has the disadvantages of small specific surface area,fast photogenerated carrier recombination rate,and low visible light absorption,which greatly limits its wide application in the field of photocatalysis.In view of the above problems,this thesis aims to design and synthesize g-C3N4 with high photocatalytic activity.By using supramolecular self-assembly technology,silver atoms and related organic molecules are incorporated into the structure of g-C3N4.In this way,the effective regulation of its morphology,specific surface area and energy band structure can be achieved,thereby greatly improving its visible light photocatalytic performance.The main research contents are as follows:1.We used melamine,cyanuric acid and silver nitrate as precursors and dimethyl sulfoxide as solvent to synthesize supramolecular self-assembly through self-assembly process,and then calcined at 550° °C to prepare a series of different silver concentrations of single-atom silver-doped porous carbon nitride nanosheets(Ag/C3N4).Compared with the same bulk carbon nitride(BCN),undoped porous carbon nitride nanosheets(PCNNs)have a larger specific surface area and higher photocatalytic activity.The doping of single atomic silver further increases the specific surface area,the separation efficiency of photogenerated electrons and holes is higher,and the activity of photocatalytic degradation of pollutants is further improved.When the doping concentration of Ag reaches 0.53%,the degradation rates of rhodamine B(RHB)and tetracycline(TC)are165.3 and 24.9 times higher than that of BCN,respectively.2.We used melamine,cyanuric acid and trimesic acid as precursors and water as solvent to synthesize supramolecular self-assembly through self-assembly process,and then calcined at 550° °C to prepare a series of carbon nitrid doped with different benzene rings concentrations(Ph/C3N4).Compared with the bulk carbon nitride(BCN),undoped carbon nitride microrods(CNMRs)have a larger specific surface area and higher photocatalytic activity.The introduction of the benzene ring can further change the morphology of the material,increase the specific surface area of the material,broaden the response range of the material to visible light,and enhance the separation efficiency of photogenerated carriers,finally realizing the improvement of the photocatalytic performance of the material.When the doping amount of benzene ring is 1%,the concentration of H2O2 produced by photocatalysis is 3.52 times that of bulk carbon nitride(BCN).