Research On Carbon Nitride-based Heterojunctions In Photocatalytic Sterilization, Tetracycline Degradation And Water Decomposition For Hydrogen Productio

The proliferation of bacteria in sewage and the abuse of antibiotics have brought great challenges to human health and the stable development of social economy.Compared with the traditional sewage treatment methods,photocatalytic technology has become a new research direction for the treatment of"water problems"due to its characteristics of green environmental protection,economic and no secondary pollution.At present,carbon nitride and other semiconductor photocatalyst materials,with appropriate band gap,good visible light absorption and excellent photocatalytic performance,stand out in the treatment of water pollution materials.In this paper,carbon nitride photocatalytic materials as the substrate,by controlling the morphology of photocatalytic materials and the construction of heterojunction,to enhance its ability in sewage treatment.The main research contents are as follows:（1）In order to achieve sterilization in sewage,we studied a 2D/2D Zn In₂S₄/g-C₃N₄catalyst,and proved its ability to produce H₂O₂under visible light irradiation and high efficiency in sterilization.The heterojunction enables fast separation and transfer of carriers,and the yield of H₂O₂is 4.27 mmol g^-1,which is much higher than that of existing catalysts.In addition,H₂O₂generated in situ can be rapidly activated to ROS with strong oxidation capacity for further sterilization.The results showed that E.coli was completely eliminated within 25 min,and S.aureus could be eliminated 98%under 60min irradiation.The preparation of the heterojunction realized the rapid production and decomposition of H₂O₂,and provided a green and efficient strategy for the sterilization of sewage.（2）In order to remove antibiotics flooding in water,a ZIF-8/g-C₃N₄heterojunction was constructed and its photocatalytic degradation of antibiotics was verified.It was found that 50%ZIF-8/g-C₃N₄had excellent photocatalytic degradation ability under light,and tetracycline could be completely degraded within 40 min.This provides a promising strategy for improving the application of traditional g-C₃N₄materials in wastewater degradation.（3）In order to achieve a breakthrough from sewage to hydrogen energy,we constructed 2D/2D Re S₂/highly crystalline g-C₃N₄（CCN）heterojunction for the first time to achieve photocatalytic decomposition of water to produce hydrogen.The hydrogen production rate of 15%Re S₂/CCN under visible light irradiation is the highest,which is 3.46 mmol g^-1h^-1,12.4 and 2.7 times higher than that of traditional g-C₃N₄material and CCN,respectively.Various comprehensive characterization showed that the excellent photocatalytic performance of Re S₂/CCN was due to the high crystallinity of CCN and the synergistic effect of heterojunction.This idea provides an effective strategy for improving the photocatalytic activity of conventional g-C₃N₄materials and producing hydrogen by decomposition of wastewater.The carbon nitride based photocatalytic nanocomposites prepared in this paper lay a good foundation for the study of using photocatalytic technology to solve water pollution and new energy problems.