| Hydrogen peroxide as a Multifunctional chemical product,which is applied to chemical synthesis,environmental remediation,medical care and other fields.Traditional hydrogen peroxide production is synthesized by anthraquinone method,which is complicated,energy-consuming and highly polluting.Solar energy drives semiconductor photocatalytic reaction as a non-toxic,mild and energy-saving method,which is an ideal alternative to hydrogen peroxide production in the future.Co-poly carbon nitride framework is one of the most promising materials for photocatalytic hydrogen peroxide production,but its poor exciton separation efficiency and low efficiency of solar energy conversion are the bottleneck for its practical application.How to regulate carbon nitride to achieve efficient catalysis is a critical issue.This paper designs a series of high activity materials and studies the catalytic mechanism and properties:（1）Regulated the nanostructure and photocatalytic reaction performance of poly（heptazine imide）framework by changing the polymerization environment..By introducing ammonium chloride into the KCl/Li Cl cocrystal salt,the new poly（heptazine imide）framework has higher porosity,better exciton dissociation and charge mobility,and more negative LUMO position,thus showing more efficient catalytic performance.Under the acidic conditions,the catalytic activity was further enhanced.The formation mechanism of hydrogen peroxide reveals the important role of superoxide radical and singlet oxygen,and found that singlet oxygen is an important intermediate for the generation of hydrogen peroxide by extracting protons from the reaction system.（2）The structure of poly（heptazine imide）framework（K-PHI）was regulated by adjusting the components of precursor.By introducing 1-methyl-1H-tetrazole-5-thiol（MTT）into the precursor for the K-PHI synthesis,the size of the layer stacking structure was reduced,the polymerization in the heptazine plane was improved,and the conduction band position was negatively shifted.The optimized K-PHI-2 showed higher performance in photocatalytic hydrogen peroxide production and pollutants degradation.Under acidic conditions,K-PHI-2exhibited a higher catalytic efficiency,with a reaction rate of up to 41.7 mmol h-1 g-1.By intruducing ozone into the reactional system,and the generated hydrogen peroxide further occurs Peroxone reaction to produce more active hydroxyl radical,which shows excellent activity in the degradation of high concentration of ciprofloxacin drugs and other organic pollutants in water.The produced hydrogen peroxide could be separated and applied in the homogeneous Fenton reaction for degradation of pollutions.（3）Synthesis of high-performance crystalline carbon nitride by directional polycondensation of potassium chloride crystal substrate surface.Using this method to synthesize the co-poly carbon nitride frame structure significantly expanding the periodic value of the planar hepzine/triazine unit,The number of layer structure is decreased.Therefore,it also exhibits a series of excellent photophysical properties,such as significantly enhanced photon absorption,greatly decreased fluorescence radiation,enhanced reduction potential,etc.The crystal co-poly carbon nitride framework shows its efficient catalytic activity in photocatalytic production of hydrogen peroxide.The production rate of hydrogen peroxide could reach 26.7 mmol h-1 g-1,and the apparent quantum yield is 25%,the catalytic activity is 23.5 times of the co-poly carbon nitride framework without KCl treatment.The synthesis method is simple and practical,and it is suitable for all the precursors of carbon nitride synthesis.Based on this material,further explore the way to enhance the interface reaction of the material and achieve a short time of high concentration of hydrogen peroxide production. |
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