Study On The Modification And Photodegradation Ability Of Graphite Carbon Nitride

Nowadays,energy shortages and environmental pollution are becoming more and more serious,and they are beginning to threaten the survival of humanity.Finding and using new clean energy is the only way to solve these problems and take the path of sustainable development.Photocatalysis,as an important way to utilize sunlight,is an ideal method to solve energy and environmental problems,and it is also one of the hot spots in the field of scientific research.Photocatalysis has a wide range of applications,including photolytic water to produce hydrogen and photodegradation of organic dyes.In this paper,graphite-like carbon nitride（g-C₃N₄）is used as the main photocatalyst,and a method for preparing porous layered g-C₃N₄ is explored.Besides,on this basis,Phosphorus（P）and Potassium（K）co-doped g-C₃N₄ with higher catalytic performance is further synthesized.In this paper,porous g-C₃N₄（PCN）with thinner layer was synthesized by a simple one-step thermal polymerization method in vapor and self-producing ammonia atmosphere.X-ray diffraction（XRD）,specific surface and porosity analysis（BET）,scanning electron microscopy（SEM）and transmission electron microscopy（TEM）were used to study its morphology and structure.The experimental results showed that the sample PCN has more pore structure and a larger specific surface area.Its pore volume and mass ratio is as high as 0.2772 cm³·g^-1,which is 2.4 times that of the blank sample BCN,and its specific surface area is 40.2 m²·g^-1,which is 2.7 times that of the sample BCN.More pore structure means better adsorption performance.As the first step of photodegradation,adsorption plays a crucial role in photodegradation performance.Larger specific surface area provides more reactive sites,directly increasing the rate of photodegradation.The adsorption capacity and photocatalytic performance of the samples were investigated by Rhodamine B photodegradation experiment.The experimental results showed that the sample PCN had greater adsorption capacity and faster photodegradation capacity,and its photodegradation rate was 0.1475 mg·L^-1·min^-1,which was 1.28 times that of the sample BCN.Using the synthetic method proposed in the above study,P and K atoms were simultaneously added by adding dipotassium hydrogen phosphate（K₂HPO₄）before thermal polymerization to synthesize P and K co-doped g-C₃N₄（CN-80PK）.Through a series of characterization methods,the morphology,chemical composition,photoreactivity and energy band structure were thoroughly studied.The results showed that the CN-80PK has a higher specific surface area,narrower band gap width,higher valence band potential,more effective photogenerated carrier separation and less photogenerated electron and hole recombination.These features allow CN-80PK to have more reactive sites,more effective light utilization capacity and higher light conversion efficiency.Rhodamine B degradation experiment results show that CN-80PK has a very high photodegradation reaction rate,which is 2.7 times that of the blank g-C₃N₄ sample,and also shows good stability.After adding different active group capture agents,degradation experiments were conducted to determine the main action groups in the process of degradation.The results showed that photo-generated holes are the key action groups for the effective and rapid degradation of Rh B.