Study On Preparation And Properties Of Cu/ZnO And Cu/TiO₂ Composite Materials

Titanium dioxide?TiO₂?and zinc oxide?ZnO?are the most widely used photocatalysts.They all show a good catalytic activity,but single phase photocatalysts exhibit low active because of the easy recombination between photo-electrons and holes.So it's necessary to modify the properties of TiO₂ and ZnO for improving the catalytic activity.Metal deposition is a modified way which have a lot of research,metal can attract photo-electrons which prolong the life of photo-electrons and holes,then the catalytic activity has a improving.TiO₂ and ZnO photocatalysts which doping nano Cu not only show better property with the irradiation of light,but also show the catalytic performance under the condition of dark.So it is necessary to have a research on the structure,morphology and catalytic properties of composite materials.In the thesis,we mainly study the influence of preparation conditions on the structure,morphology and catalytic properties of Cu/ZnO composite materials and Cu/TiO₂ composite materials.1.At room temperature,chemical reduction method was used to synthesize Cu/ZnO composite materials by using cetyl trimethyl ammoinum bromide?CTAB?as cationic surfactant,using copper chloride?CuCl₂?as copper source,using hydrazine hydrate?N₂H₄·H₂O?as reducing agent and ZnO as the carrier,the catalytic activity was studied through the degradation of methyl orange?MO?.The result indicated that nano Cu which deposited on the surface of ZnO increased gradually and reunion phenomenon became more and more obvious as the improving of the concentration of copper source,namely the reducing of the mass of ZnO.Its catalytic activity showed the reduction after the first increasing,when the concentration of copper source reached 55.6%,Cu/ZnO composite material had the best catalytic activity;in the same way,the reaction gradually reflected completely and nano Cu which deposited on the surface of ZnO gradually increased as the reaction time increased.However,not the longer of the reaction time,the better of the properties of catalytic.The degradation efficiency of MO prepared with 3 h is the highest,reaching 95%.In addition,the degradation mechanism of Cu/ZnO composite material was explored.Besides,the stability of Cu/ZnO composite material was studied by recycles.2.At room temperature,chemical reduction method was used to synthesize Cu/TiO₂ composite materials by using cetyl trimethyl ammoinum bromide?CTAB?as cationic surfactant,using copper chloride?CuCl₂?as copper source,using hydrazine hydrate?N₂H₄·H₂O?as reducing agent and TiO₂ as the carrier,the catalytic activity was studied through the degradation of methyl orange?MO?.The influence of the concentration of copper source and the reaction time on the structure,morphology and the catalytic activity of Cu/TiO₂ composite material were studied.The result indicated that when the concentration of copper source reached 38.6%and the reaction time reached 4 h,Cu/TiO₂ composite material had the best catalytic activity,the degradation efficiency of MO reached 95.8%.Besides,the degradation efficiency of MO was still more than 90%after fifth cycles.3.We used Cu/ZnO composite material and Cu/TiO₂ composite material to degrade formaldehyde?HCHO?,the dosage of composite material,the concentration of HCHO and the light source on the catalytic activity were studied.The result indicated that the degradation efficiency of Cu/ZnO composite material was better than Cu/TiO₂ composite material,however,not the more the dosage of composite material,the better the catalytic activity.The degradation efficiency of HCHO prepared with 0.5 g of the dosage of composite material is the highest,reaching 97.7%.The concentration of HCHO had a small influence to the degradation efficiency of HCHO.The degradation efficiency of HCHO prepared with 20 ?g/mL of the concentration of HCHO is the highest,reaching 98.2%.At the same time,visible light also had an effect on the degradation of HCHO,but the degradation efficiency was not high.In the thesis,composite materials were synthesized at room temperature.The technological process is very simple and the charge is low,at the same time,Cu/ZnO composite material and Cu/TiO₂ composite materials exhibit high degradation efficiency.So we believe that they would be found to be an practical application in sewage treatment and air purification.