Preparation And Photocatalytic Performance Of 3D Flower-shaped ZnO Nanocomposites

Photocatalytic technology,as a kind of sustainable green technology,has attracted great attention due to its wide application in energy regeneration and environmental remediation,especially in the application of semiconductor in photocatalytic degradation of organic pollutants in water.The efficiency of photocatalysis is mainly affected by the response range of catalyzator to sunlight,the composite efficiency of photogenerated electron hole pair and the possible chemical reaction sites in photocatalysis.Nanocomposites photocatalyst has better photocatalytic efficiency than pure component photocatalyst because it can improve the band gap position and structure performance of pure component photocatalyst.Among them,zinc oxide nano composite material,as an efficient and multifunctional energy conversion and photochemical reaction material,has great application potential.Aiming at some disadvantages of photocatalyst,this paper synthesized a 3D flower-like ZnO nanomaterial with higher adsorption capacity,and the surface of ZnO was modified by Ag and Cu₂O to obtain nano composite material,which can broaden the range of ZnO light response,improve the separation efficiency of electron hole pair,and enhance its photocatalytic efficiency.The photocatalytic performance and mechanism of ZnO nanocomposite were also explored.The main research content is covered the following parts:1)We firstly synthesized the 3D flower-like ZnO nanomaterial with a high dispersibility and a diameter of about 1600 nm by the precipitation method,and then Ag and Cu₂O were supported on the ZnO by the light deposition method and the chemical reduction method,respectively,to obtain a series of ZnO nanocomposites.The photocatalytic performance of nanocomposites was evaluated by degrading Congo red（CR）under xenon light.The results show that the synthesized nanocomposite has better pore characteristics and has a good adsorption effect on Congo red.This provides a good basis for heterogeneous photocatalysis,and the nanocomposite has a light response compared to pure ZnO.Wide range,reduced photonelectron-hole pair recombination ability,reduced forbidden band width and other characteristics to meet the design requirements of photocatalysts.Ag@Cu₂O/ZnO nanocomposites not only show good photocatalytic performance but also have good cycle stability,and the degradation rate of Congo red reaches 98%.2)Research on the photocatalytic mechanism of nanocomposite Ag@Cu₂O/ZnO found that the degradation of Congo red is mainly achieved by the generation of active substance and free radicals.The use of single sacrificial agents for scavenging of excited holes（h⁺）,superoxide radicals（·O₂^-）,and hydroxyl radicals（·OH）found that excited holes play a major role in photocatalytic degradation of Congo red.The presence of Ag nanoparticles can better capture photo-generated electrons and promote the separation of electron-hole pairs.Cu₂O forms superoxide radicals at Ag nanoparticles by adsorbing oxygen in the air,so the catalyst Ag@Cu₂O/ZnO exhibits better catalytic performance.