Preparation Of ZnO Photocatalytic Materials And Performance Studies

At present,the environmental pollution problem has seriously restricted the development of human society.How to solve these problems has been widely concerned.Photocatalytic technology emerged as a green and efficient new environmental management method.Zinc oxide has the advantages of stable performance and high quantum yield,and it is a commonly used photocatalytic material.As a photocatalyst,the photocatalytic activity of zinc oxide is directly related to factors such as morphology and crystal structure.In order to understand the relationship between the morphology and photocatalytic activity of zinc oxide nanomaterials,a variety of morphologies of zinc oxide nanomaterials were successfully prepared by anion regulation.The photocatalytic performance of pure zinc oxide nanomaterials is improved by loading metals.In this study,four anions of acetate ion,sulfate ion,chloride ion and nitrate ion were used to regulate the micro-nano structure of zinc oxide.Zinc oxide nanomaterials with chain,multi-layered with hexagonal flaky,plate-like and flower-like structures were synthesized in two steps by uniform precipitation method.Through the control variable method,it was found that the zinc oxide nanomaterials of four morphologies were assembled from zinc oxide seeds.When the reaction time is 6h and the precipitant concentration is 0.4mol/L,the zinc oxide nanomaterial with the most regular morphology and the most stable structure can be synthesized.Through photodegradation experiments of methyl orange,it can be known that the photocatalytic activity of the four materials is from high to low: chain zinc oxide > flower-like zinc oxide > platy zinc oxide > hexagonal flaky zinc oxide.The free radical trapation experiment determines that the photogenerated hole h+ plays a major role in photodegradation.In order to further improve the photocatalytic efficiency of zinc oxide,this study carried out the doping of transition metals and the recombination of noble metals on the basis of chain-like zinc oxide nanomaterials.Elemental analysis indicates that the transition metals Co and Ni can occupy the Zn site during the material synthesis process,affect the internal charge distribution of the material and destroy the chain structure of pure Zn O,thereby reducing the photocatalytic activity of the material.It was confirmed that the chain structure composed of the series of nanoparticles has excellent photocatalytic activity and stability.The loading of noble metal Ag has no effect on the assembly process of Zn O chain structure.XPS analysis shows that Ag element exists in the form of metal element and is not incorporated into the zinc oxide lattice.The Ag/Zn O nanocomposite with chain structure is successfully synthesized.The results of photodegradation of methyl orange showed that the loading of noble metal Ag increased the photocatalytic activity of zinc oxide.When the loading of Ag nanoparticles was 1%,the photocatalytic performance of the composite was the highest.