The Preparation Of Graphite Phase Carbon Nitride GC₃N₄ And Its Composite Materials And Its Photocatalytic Antibacterial Properties

In view of the increasingly serious bacterial contamination problem,the research and development of highly effective and durable bactericidal photocatalyst is an effective way.Photocatalyst can produce some active groups(·OH,O₂^·-and h⁺,etc.)to destroy the organic structure of bacteria,and then achieve the purpose of killing bacteria.Graphitic carbon nitride?g-C₃N₄?semiconductor photocatalyst has been widely studied due to its advantages such as good biocompatibility,moderate band gap and high stability.However,it still has some deficiencies such as low specific surface area and high photosynthetic recombination rate.In this paper,morphological control and chemical composite is used to enhance the photocatalytic antibacterial property of g-C₃N₄ nanosheet.This work includes the preparation of antibacterial photocatalysts such as g-C₃N₄ nanosheets,Ag/Polydopamine?PDA?/g-C₃N₄ composites and Ag@AgCl/PDA/g-C₃N₄ composites.The antibacterial performance of the samples was proved and investigated by antibacterial tests of E.coli.?Inhibition zone,Minimal inhibitory concentrations,Minimum bactericidal concentration,etc.?The relationship between antimicrobial property and material structure was further explored.The specific research contents and conclusions of this work are as follows:1.Porous g-C₃ N₄ nanosheets were prepared by several thermal oxidation exfoliations with urea as the raw material.The morphological analysis results?SEM,TEM and AFM?showed that the thickness of the material decreased and a large number of regular holes appeared with the progress of thermal oxidation exfoliations.The thickness could be reduced to 0.45 nm and the specific surface area was as high as¹48.50 m²g^-1.Antibacterial tests showed that porous g-C₃N₄ nanosheet under visible light has a good antibacterial effect.The minimum inhibitory concentration?MIC?against E.coli was 800 ppm.2.Ag/PDA/g-C₃N₄ composites were successfully prepared in the ice bath by in-situ self-assembly with NaBH₄ as a reducing agent.Spherical silver nanoparticles?Ag NPs?with a diameter of about 10 nm were loaded on the g-C₃N₄ nanosheets.Due to the charge transfer mechanism of Ag and the excellent antibacterial ability of Ag NPs,the synergistic sterilization of reactive oxygen groups?ROS?and Ag NPs was achieved to kill bacteria.Highly effective antibacterial with low Ag content was achieved under visible light.The minimum inhibitory concentration?MIC?and minimal bactericidal concentration?MBC?against E.coli was 45 ppm and 30 ppm,respectively.The composite also showed a good biocompatibility and circulatory stability due to the function of polydopamine?PDA?.3.Ag@AgCl/PDA/g-C₃N₄ composites were prepared by a green,non-toxic and simple light reduction method.Its morphology can be controlled by adjusting pH value.When the pH value was adjusted to 9,the nanoparticles on the material can be most evenly dispersed.The composite has a good photocatalytic antimicrobial property,and the MIC value can be reduced to 25 ppm as low as possible.This material has a low toxicity to normal cells HOSEpic and HUVEC,but high toxicity to ovarian cancer cells A2780 and SKOV3,so this material has a good research prospect in the biological field.