Construction Of ZIF-8@g-C₃N₄ Heterostructure And Enhancement Of Its Photocatalytic Properties

The development of human civilization has always been accompanied by energy and environmental problems,especially since the 21 st century,with the accumulation of bad results,environmental protection and sustainable development has become a worldwide topic.At present,photocatalysis technology is very popular in the field of environmental protection because of its advantages of green,environmental protection and sustainability.The catalyst is the core of photocatalysis technology.The graphite like carbon nitride?g-C₃N₄?has a response to visible light and has the potential to become a photocatalyst.However,its photocatalytic performance is not high,the generated photocarriers are easy to compound,and its light absorption range is narrow?< 475nm?,the specific surface area is low,and the active sites are limited,which has been greatly restricted in the application.Therefore,in this paper,g-c3n4 and zif-8 are used as carriers to construct different heterostructures,and their applications in environmental pollution are discussed.The main research contents are as follows:?1?ZIF-8@g-C₃N₄ heterogeneous composite catalyst was prepared by self-assembly method at room temperature,and its photocatalytic activity was evaluated by degradation of methylene blue?MB?dye under simulated visible light source.The results show that the catalytic activity of ZIF-8@g-C₃N₄ heterogeneous composite catalyst is higher than that of ZIF-8.ZIF-8@g-C₃N₄-10?ZCN-10?has the highest catalytic activity,and the degradation rate of methylene blue reaches 90.4% after 120 min of illumination.After 5 cycles,ZCN-10 is still stable.In addition,by analyzing the properties of ZIF-8 and g-C₃N₄,the mechanism of improving the photocatalytic performance of heterogeneous composite photocatalyst was proposed.?2?Ag@ZIF-8@g-C₃N₄ composite photocatalyst was prepared by self-assembly method.The photocatalytic activity of methylene blue?MB?was evaluated by degradation of methylene blue?MB?under simulated visible light source.The results show that the composite photocatalyst with ternary heterostructure has more excellent photocatalytic performance,among which Ag@ZIF-8@g-C₃N₄-10?AZC-10?sample has the best photocatalytic performance.After 120 min of light,the degradation rate of methylene blue can reach 96%,and after 5 cycles of experiments,the catalytic degradation efficiency of human remains 92.5%.In addition,the mechanism of photocatalytic enhancement was studied.?3?g-C₃N₄@ZIF-8@@MoS₂ composite photocatalyst was prepared by hydrothermal method,and its photocatalytic activity was evaluated by degradation of methylene blue dye under simulated light source.The results show that the composite photocatalyst with ternary heterostructure shows excellent photocatalytic performance,and g-C₃N₄@ZIF-8@MoS₂-7.5?CZM-7.5?shows the best photocatalytic performance.After 90 minutes of light,the degradation rate of methylene blue can reach 98.7%,and after 5 cycles of experiments,the degradation rate of methylene blue decreases by 6.3%,and the degradation mechanism of composite materials is proposed.