Facile Synthesis Of Mesocrystal ZnO?Ag/ZnO?ZnO/RGO And Their Photocatalytic Performance

Photocatalytic technology is a common method for sewage treatment in recent years,and has a very wide application,so the searchers have been searching for photocatalyst that has good photocatalytic activity.The controlled synthesis of photocatalyst was an important part in the field of photocatalytic materials for the activity of photocataly largely depends on its morphology and structure.ZnO photocatalyst has been widely studied and applied.In this paper,the facile synthesis of mesocrystal ZnO and its influence factors in the synthetic process were studied systematically,and we also studied the preparation of Ag/ZnO and ZnO/RGO.The photocatalytic activity of the materials was further studied,and the possible formation mechanism was proposed.The main work and research results are listed as follows:?1?The facile synthesis of ZnO mesocrystals and its photocatalytic activityZinc acetate solution,sodium hydroxide solution and hydrochloric acid solution were used as the raw material.Bundle-like Zn?OH?₂ mesocrystal were synthesized by a precipitation-roasting method in the condition that the reaction time is 1 hour and the reaction temperature is 20?.The morphology and structure of the products were characterized by XRD?SEM?PL and DRS measurements.Experimental results show that H⁺plays a crucial role in the formation of the structure,when the mole ratio of H⁺:Zn²⁺is 1:1.3,the bundle-like mesocrystal can only be prepared.All the products exhibited uniform bundle-like shape with 2-5?m in length and 0.5-1.5?m in diameter.ZnO mesocrystal can be obtained after calcination at 600?.All the ZnO products were composed of nanoparticles with an average particle size of 60 nm.The ZnO mesocrystal exhibited excellent photocatalytic activity and stability,which means that bundle-like ZnO mesocrystal is a kind of good semiconductor photocatalytic materials in wastewater treatment.Finally a possible formation mechanism was discussed.?2?The preparation of Ag/ZnO composite materials and their photocatalytic performanceIn this section,Ag/ZnO composite materials with different silver contents were synthesized by the silver mirror reaction with mesocrystal ZnO as raw material.The morphology and structure of the products were characterized by XRD?EDS?PL?DRS measurements.The results shows that Ag particles actually loaded on the surface of ZnO mesocrystal and the strong interfacial coupling between Ag and ZnO reduced the surface defects of ZnO.Ag/ZnO composite materials exhibited improved photocatalytic activity and stability due to the electron capture effects of Ag.When the content of Ag was 5%,the photocatalytic activity is best.It is proved that photoproduction hole h⁺is the main active substance through the exploration of photocatalytic mechanism.?3?The preparation of ZnO/RGO composite materials and the study oftheir photocatalytic performanceIn this paper,we prepared grapheme oxide?GO?by an oxidation-reduction method,ZnO/graphene composite materials with different contents of graphene were synthesized by an in-situ composite method with the GO as the precursor,and we add the hydrazine hydrate as reducing agent to reduce the GO to RGO.The graphite and graphite oxide were characterized by XRD?TEM?PL?DRS.The results indicate that the graphite oxides were single-layer sheet and high oxidation degree.ZnO/RGO composite materials show higher photocatalytic activity because the RGO has good electrical conduction effect that can restrain the composite between electrons and holes,and the optimal value of graphene content is 10%in the composite materials.We put forward the formation mechanism of ZnO/RGO composites at last.