UiO-66-NH₂ Post-synthesis Modificated With Ag/AgCl And Its Rhodamine B Photodegradation Performance

Synthetic dyes are widely used in tanning,paints and cosmetics industries.Dye residues in wastewater can cause serious environment pollution,even at low concentrations.Hence,it is essential to degrade dye residues into non-hazardous products before discharge.Photodegradation,which utilizes inexhaustible solar energy to decompose dyes,is efficient and environmentally friendly.Ui O-66-NH₂,as typical visible-light responsive Zr-based Metal-Organic Frameworks（MOFs）has attracted great interests in recent years.In this work,a series of Ui O-66-NH₂/Ag/Ag Cl composites were designed.The performance of photocatalytic degradation of Rhodamine B（Rh B）under visible light was systematically studied.The main research results are as follows:1.Herein,the facile precipitation-photoreduction method was used to post-synthetically decorate Ag/Ag Cl on the surface of Ui O-66-NH₂ and form heterostructure without changing the skeleton of MOFs.UV-vis results show that Ag NPs in the Ui O-66-NH₂/Ag/Ag Cl structure has a surface plasmon resonance（SPR）effect.The photocatalytic activity of Ui O-66-NH₂/Ag/Ag Cl composites was investigated by degrading Rh B solution under visible light.Ui O-66-NH₂/Ag/Ag Cl with 16.2%Ag loading displays the highest degradation rate,which is about 10 times and 4 times to pristine Ui O-66-NH₂ and Ag/Ag Cl,respectively.The SPR effect of Ag enhances the absorbility of visible light.The formation of heterostructure accelerates the separation of photogenerated electrons and holes.The synergy of them greatly improves the activity of photodegradation.Active species capture experiments confirms that superoxide radicals（·O₂?）is the main active species during photodegradation of this system.The SPR effect of Ag NPs can promote the formation of·O₂?.2.UiO-66-NH₂/Ag/AgCl samples with optimal Ag content were selected to investigate the effects of different synthesis methods on the morphology,ligand defects and photocatalytic properties of Ui O-66-NH₂.Studies have shown that carboxylic acid can increase the ligand defects of Ui O-66-NH₂,Ui O-66-NH₂ with more ligand defects has better conductivity,higher photo-generated carrier separation efficiency and faster charge transfer.These improved optoelectronic properties facilitate the transfer and separation of photogenerated carriers in the Ui O-66-NH₂/Ag/Ag Cl system,which effectively improves the photocatalytic ability of the Ui O-66-NH₂/Ag/Ag Cl system.The degradation rate is 6.3 times that of the Ui O-66-NH₂/Ag/AgCl sample with less defects in MOFs.