Photocatalytic Properties Of Ag/AgCl-based Visible-light-driven Photocatalysts Synthesizd By Template Method

With the rapid development of industry,water pollution,especially wastewater containing organic pollutants,poses a serious threat to the ecological environment and human health,wihch has become one of the important issues that restrict human sustainability.Photocatalytic degradation has attracted widespread attention from researchers due to its rapid decomposition,thorough treatment,and no secondary pollution.Semiconductor photocatalyst,as a key substance in the photocatalytic system for absorbing sunlight and generating excited electron-hole pairs,still faces the problems of practical application such as low utilization efficiency of visible light and short lifetime of photogenerated carriers.Therefore,it is of great significance to design and prepare photocatalysts with high visible light utilization efficiency and high photogenerated electron-hole separation capability for efficient degradation of organic pollutants in wastewater.Ag/AgX?X=Cl,Br,I?has become a stable and promising plasmonic visible-light-driven photocatalyst.In this system,Ag nanoparticles can absorb visible light to generate hot electrons due to the surface plasmon resonance effect and be injected into AgX for photocatalytic reaction.However,the hot electrons injected into the AgX conduction band will diffuse to the interface between Ag and AgX and recombine with the holes in Ag,resulting in the reduction of the photocatalytic properties of Ag/AgX composites.Moreover,Ag/AgX photocatalyst has a higher cost due to containing precious metal Ag.Therefore,how to design and fabricate low cost,high visible light utilization efficiency and photogenerated carrier separation efficiency is still a major problem for Ag/AgX visible-light photocatalysts.In order to solve the above problems,the hollow micro-cube structure of Ag/AgCl and Z-scheme Cu₂O/Ag/AgCl micro-cubic visible-light photocatalysts were synthesized by template method,and the effects of the composition of the obtained photocatalysts on visible-light absorption and photocatalytic performance were studied.It provides new ideas and research basis for the development of Ag/AgX plasma-based visible-light-driven photocatalysts.The main results are as follows:?1?In this paper,Ag/AgCl hollow microcubes with different composition ratios were prepared by using Ag hollow microcube template and adjusting the amount of oxidant FeCl₃.Constructing a hollow micro-nano structure not only enhances the visible light absorption capability by multiple reflections of light in the cavity,but also reduces the costs of photocatalysts.The hollow microsphere shell is a porous structure composed of small particle size nanoparticles,not only contribute to the exposure of active sites,but also shortens the diffusion path of electron-hole pairs and accelerates the carriers reaching the active sites of photocatalyst surface and thus improving the photocatalytic activity.By controlling the composition ratio of Ag and AgCl,the contact surface area of the heterointerface can be controlled,and the photocatalytic activity can be improved.The results show that when the ratio of Ag to AgCl is 1:3,the Ag/AgCl hollow microcube visible-light-driven photocatalyst has the best photocatalytic activity.?2?Cu₂O,a p-type semiconductor with narrow bandgap?2.0-2.2 eV?and Ag/AgCl were used to build a Z-scheme photocatalytst.In the system,Cu₂O absorbs visible light to generate photoelectron,which recombines to the hole of noble metal Ag.The process of charge transfer prevents the hot electrons in the AgCl conduction band to reflow back to the metal Ag,and promotes efficient separation of photo-generated electrons and holes and improves their photocatalytic efficiency.In this paper,Cu₂O is used as a template to prepare Cu₂O/Ag microcubes,and CuCl₂ is selected as an oxidant,because CuCl₂ can not oxidize Cu₂O and Cu₂O/Ag/AgCl can be successfully prepared.The composition ratio of Ag to AgCl in Cu₂O/Ag/AgCl is controlled by controlling the amount of CuCl₂.The effect of the composition on the morphology,and photocatalytic efficiency was studied.Then photocatalytic activity of Cu₂O/Ag/AgCl is the highest when the ratio of Ag to AgCl is 1:2.