The Preparation Of New-types Of Graphitic Carbon Nitride Composite And Their Applications In Photocatalysis

With the rapid development of society and economy,global resources are exploited excessively,including oil,natural gas,coal,etc..At the same time,people pose irreparable damage to the environment.Therefore,we are faced with the energy crisis and environmental pollution problems.Hence,semiconductor photocatalytic technology arises.It can use solar energy to degrade pollutants,and also could split water into H2.It is encouraging news,because it can not only solve the problem of shortage of resources,also can realize the environmental restoration.Most semiconductor photocatalyst are based on TiO2.However,TiO2 based semiconductor photocatalyst are still limited to experimental application after years of research due to its poor solar energy utilization and inefficient quantum efficiency.To develop a new type of efficient semiconductor photocatalyst is imperative.Graphitic carbon nitride(g-C3N4)as a non-metallic polymer composed of C and N which are abundant on the earth,and it possesses many advantages,such as,low synthesis cost and varied preparation methods.What's more,its lower band gap(Eg ?2.7 eV)and special electronic structure make it exhibit great photocatalytic activity.Unfortunately,it is still limited by low surface area and poor electrical conductivity.Finally,we synthesized modified graphite carbon nitride by doping transition metal,and studied their structure and photocatalytic activities by a series of characteristic methods.The major results are as follows:(1)Graphitic carbon nitride with doping iron was prepared via melamine,cyanuric acid and xanthine.Through the high angle of annular dark-field scanning transmission electron microscope(HAADF-STEM)instrument,we found irons exist in the form of single atoms.By XRD,XPS,UV-vis,PL and other methods,we found that the composite displayed stronger light absorption ability,narrowed band gap and effective separation of photogenerated electron-hole pairs and better photoelectric chemical characteristics.We also studied the photocatalytic performance of the material by photocatalytic degradation of acetamiprid in photo-Fenton system.(2)The modified g-C3N4 was synthesized by doping transition metal iron with melamine and theobromine.Its structure was analysised by TEM,XRD,UV-vis.We also conducted experiments to degradate RhB under the visible light in the presence of PS.The results showed that the composite had great photocatalytic activity.Especially after seven cycle experiments,it still keeped good photocatalytic performance,so it possessed high stability.(3)A Co-doped carbon nitride was synthesized through the thermal polymerization via melamine,cyanuric acid and xanthine.TEM maps showed that metal clusters were evenly dispersed in the graphitic nitride carbon.We found that it had excellent photocatalytic degradation of pollutants through a variety of characterization methods and photocatalytic degradation experiments.