| As a visible-light responsive semiconductor,graphitic carbon nitride（g-C3N4）is widely used in photocatalysis,sensors,and catalyst’s carriers due to its low density,stable physicochemical properties,good biocompatibility,moderate band gap and metal free composition.At present,there are many methods for preparing g-C3N4nanomaterials,however,most of them suffer from several drawbacks such as low synthesis efficiency,complicated process,low yield of products,and harmful to environment.The high-energy microwave method has many advantages,covering high heating speed,high selectivity,small thermal inertia,energy saving and environmental protection.It has become a promising method to synthesis g-C3N4 nanomaterials.Herein,the g-C3N4 nanosheets with different structures were synthesized via high energy microwave method.Corresponding morphologies,structures,optical and electrochemical properties of as-obtained samples were characterized and analyzed by various analytical techniques.The photocatalytic performance was evaluated by investigating the ability of samples to degrade Rhodamine B（RhB）aqueous solution,and the way to enhance the photocatalytic activity was explored.In addition,the field emission performance and mechanism of boron-doped carbon nitride（B-g-C3N4）nanosheets were investigated and analyzed.The electrochemiluminescence performance and principle of phosphorus-doped carbon nitride（P-g-C3N4）nanosheets were studied and analyzed.The main contents and conclusions are as follows:（1）Study on the structural feature of graphene-like graphitic carbon nitride nanosheets（g-C3N4-NS）synthesized via high-energy microwave method.The g-C3N4-NS was synthesized successfully by microwave irradiation at 560°C for 10 min,using carbon fiber as microwave absorber,melamine as precursor,respectively.Compared with thermal condensation method,the preparation efficiency of high-energy microwave method was obviously improved.Compared with products acquired by the traditional synthesis methods covering ultrasonic exfoliation and oxidative etching,the surface of g-C3N4-NS obtained under high-energy microwave irradiation was smooth and flat.There was no obvious wrinkle structure on the surface of g-C3N4-NS and brittle fracture occured,indicating that the nanosheets was rigid.Owning to many C=N,C≡N bonds existed in the nanosheets,and the internal stress generated along with intense energy transfer and exchange during the synthesis,the g-C3N4-NS does not exhibit the flexible surface,which is the characteristic of traditional graphene-like g-C3N4.（2）Study on the structural feature,photocatalysis and field emission properties of boron-doped graphitic carbon nitride（B-g-C3N4）nanosheets synthesized via high-energy microwave method.B-g-C3N4 was synthesized successfully by high-energy microwave method using carbon fiber as microwave absorber,boric acid modified melamine as precursor,respectively.The results showed that B-doping could effectively regulate the morphology and electronic structure of g-C3N4.The as-synthesized B-g-C3N4 could degrade RhB aqueous solution efficiently under visible light irradiation and showed excellent field emission property.When the adding amount of boric acid was 10wt.%,1.0B-g-C3N4 was characterized as an ultra-thin two-dimensional（2D）nanosheet structure along with dendritic edges,showing the highest photocatalytic performance and field emission performance.Under the visible-light irradiation,1.0B-g-C3N4 just took 30 min to degrad 92.9%of RhB.In addition,1.0B-g-C3N4 possessed an extremely low turn-on field of about 0.35 V/μm,the highest current density of 3.51 mA/cm2 and a large field-emission factor of about 4820.（3）Study on the structural feature,photocatalysis and electrochemiluminescence properties of phosphorus-doped graphitic carbon nitride（P-g-C3N4）nanosheets synthesized via high-energy microwave method.P-g-C3N4 was successfully synthesized by high-energy microwave method using carbon fiber as microwave absorber,diammonium phosphate modified melamine as precursor,respectively.The results showed that P-doping could effectively regulate the morphology and electronic structure of g-C3N4.The as-synthesized P-g-C3N4 could degrade RhB aqueous solution efficiently under visible light irradiation and showed excellent electrochemiluminescence property.When the adding amount of diammonium hydrogen phosphate was 5wt.%,0.5P-g-C3N4 was characterized as an ultra-thin 2D nanosheet morphology,showing the highest photocatalytic performance and electrochemiluminescence performance.Under the visible-light irradiation,0.5P-g-C3N4 just took 35 min to degrad 92.7%of RhB.In addition,the electrochemilluminescence intensity of 0.5P-g-C3N4 was about 27.6 times higher than that of g-C3N4. |
