Study On The Photocatalytic Performance Of Structural Defect-engineered UiO-66-NH₂-based Composites

With the development of society,the demand for energy is increasing.The energy crisis and the accompanying environmental problems are becoming more and more serious,and the development and utilization of new energy resources are urgently needed.Photocatalytic technology has been widely used in production and life because it can effectively use solar energy to offer hydrogen energy needed by humans and solve pollution problems.As a new type of photocatalytic material,UiO-66–NH₂ is favored by photocatalysis researchers because of its visible light response capability.In this paper,structural defects（linker defects and cluster defects）are rationally constructed in UiO-66-NH₂,and it is found that structural defects can improve the photocatalytic activity,which makes the subject of great significance and broad application prospects.Linker defects with different contents were successfully constructed in UiO-66-NH₂ by controlling the amount of acetic acid added during the synthesis process,and Ag/AgCl surface plasma was constructed on its surface for rhodamine B/p-chlorophenol photodegradation.Enhancing photon absorption and promoting the separation of photogenerated carriers are two major ways to improve photocatalytic activity.Due to its surface plasmon resonance（SPR）effect,Ag has a strong visible light absorption capacity in the visible light region.Heterostructure and structural defects are promising methods to improve the separation of photogenerated electron-hole.The ternary coupling effect of linker defects in UiO-66-NH₂,Ag plasmon,and heterojunction can simultaneously improve the separation of photogenerated carriers and light absorption.The TGA,NMR and BET measurements indicate an increase in linker defects.The UV-vis DRS clearly shows the Ag SPR effect.The XRD,SEM and TEM results confirmed the formation of heterostructures.Compared with the Rh B degradation of the original UiO-66-NH₂ under visible light,its linker defects can increase the photocatalytic activity by 2 times,Ag plasmon and heterostructure can increase the photocatalytic activity by 18 times,and the ternary coupling can significantly increase the activity by 130 times.For UiO-66-NH₂-X,it has almost no degradation ability for 4-CP.After loading Ag/AgCl,the ternary coupling effect can increase the activity by 2.3 times compared to the effect of Ag/AgCl alone.Reactive species capture experiments show that·O₂^-/h⁺is the main reactive specie that degrades Rh B/p-chlorophenol,which identify the improved redox capacity.Cluster defects with different contents were successfully constructed in UiO-66-NH₂ by controlling the amount of benzoic acid added,and the effect of cluster defects on photocatalytic degradation of Rh B was studied.XRD,TGA and other characterization methods were used to prove the existence and content changes of cluster defects.Experiments show that UiO-66-NH₂-10Benz has the best photocatalytic activity.Active species capture experiments show that·O₂^-is the main reactive species for Rh B degradation.A proper amount of cluster defects can improve the photocatalytic activity by promoting the transfer and separation of photogenerated carriers.