Improvement Of Preparation Technology Of Graphite Carbon Nitride And Its Photocatalytic Performance

The long-term use of the earth's resources has led to energy depletion,environmental deterioration etc.trouble,it have become more sharp-pointed.In this trend,it provides a historical opportunity for efficient and clean renewable energy to replace traditional resources.The photocatalysis technology can directly acquire,convert and store the renewable solar energy,which is of particular concern to researchers.Visible light-responsive g-C₃N₄not only has a small band gap width?².7 eV?,good stability and unique electronic structure,it is only composed of abundant non-metallic C and N on the earth,and is widely used in the fields of environmental cleanliness and hydrogen production.However,g-C₃N₄ has a serious defect,which is low photogenerated charge separation efficiency,and generated e^--h⁺pair is easy recombination,resulting in its low quantum efficiency.Therefore,reasonable design of new preparation strategies to promote the abruption of light generation e^--h⁺pairs and improve their life is the main task at this stage.In this paper,the g-C₃N₄ have been studied by combined improving the preparation method with doping modification.The primary substance as follows:A series of halogen-doped g-C₃N₄ nanorods were prepared by saturated salt solution-hydrothermal post-treatment,and the photocatalytic ability of the prepared catalysts were investigated.PL result shows that the peak strength of halogen-doped g-C₃N₄ was significantly lower than that of pure g-C₃N₄,the doping of halogen accelerated the carrier charge migration rate and inhibited the recombination of e^--h⁺pairs,and the quantum yield and catalytic activity of the samples were improved.The experimental results of photocatalytic H₂O₂ production showed that the photocatalytic activity of Br-doped g-C₃N₄was the highest,which was 2 and 1.25 times higher than pure g-C₃N₄ and Cl-doped g-C₃N₄,respectively.In addition,compared with the traditional co-condensation method,the catalyst prepared by saturated salt solution-hydrothermal post-treatment shows a larger surface area,Faster separation rate of e^--h⁺pairs.Saturated salt solution-hydrothermal post-treatment changed the morphology and surface area of as-prepared g-C₃N₄ catalyst,as well as doped the halogen atoms into g-C₃N₄ lattice,simultaneously.These synergistic factors had a significant effect on the photocatalytic performance of g-C₃N₄.N vacancies,oxygen co-doped g-C₃N₄ composite photocatalyst was synthesized via DBD plasma treatment,and the photocatalytic capability of the as-prepared catalysts were investigated.The N vacancies,oxygen are introduced into the g-C₃N₄ lattice by plasma treatment,simultaneously.And visible absorption and the position of energy band is changed.The experimental results of photocatalytic N₂ fixation show that the co-doped g-C₃N₄ exhibits the highest ammonium ion yield,which is 2.2 and 20 times higher than the only N vacancies doped g-C₃N₄ and pure g-C₃N₄,respectively.The results of experiments and density functional theory calculations show that,compared with individual N vacancies doping,the introduction of oxygen can prolong the bond length of N?N,enhance the electron contributing capability of N vacancies,and improve the activation ability of N₂ molecule,leading to the photocatalytic N₂ fixation ability was improved effectively.