Chemical Bath Deposition Of Nano-ZnO And Its Gas Sensing Properties

In recent years,wit h the rapid development of the t imes and the increasing progress of industry,the proble m o f environmental po llut io n is beco ming more and more serious,and the detection o f toxic gases in the environment beco mes more and more important.The research of gas sensor,th erefore,has gradually attracted people’s attent ion,and the metal oxide semiconductor sensor has beco me one of the mo st widely used sensors in most studies.The gas sensing performance of this kind of gas sensor is not only related to the properties o f th e material it self,but also related to the nanostructure of the material.By increasing the specific surface area of the material,the adsorption number o f gas mo le cules can be increased.In order to further improve t he gas sensing performance o f the gas s ensor.For this purpose,in this paper,ZnO powders and thin films were prepared by chemical bat h deposit io n,and the surface morpho logy and nanostructure were characterized.At the same t ime,the gas sensing properties o f the materials were systemat ically tested.The main result s are as fo llows:The ZnO powders prepared by chemical bath deposition mainly include spherical powders composed of multiple ZnO nanowires and petal-shaped powders composed of multiple ZnO nanorods.For ZnO flake powder sphere and ZnO rod powder flower,the thickness of single nano-sheet is about 20nm,the diameter of single nanorod is about 50nm,and the size of three-dimensional sphere and petal are 1-5μm and 3-5μm,respectively.The test results show that the optimum working temperature of ZnO flake powder ball is 70℃,and the response value of 100ppm H₂S is 22.In addition,it also has the best selectivity to H₂S gas,while the ZnO rod powder flower shows relatively weak gas response to H₂S.The ZnO nanosheet array films were prepared by sol-gel method combined with chemical bath deposition.After a series of tests and characterization,it is concluded that the thickness of a single nano-sheet in the array is about 20nm,and the thickness of the film is 1.5μm.Through the gas sensing test,it is found that the best growth time of the film is 2h,and the film has excellent gas sensing response to NO₂ gas and the best gas selectivity.When ultraviolet light is applied in the testing process at room temperature,it is found that the sensitivity of the sensor S4 prepared by the thin film to 10ppm NO₂ is as high as 2737,the detection concentration can be as low as 50ppb,and the gas sensing response value is 1.2.And the response and recovery rate is very fast,and the stability is general.The ZnO nanorod array films were prepared by so l-gel met hod co mbined wit h chemical bath deposit io n.After a series o f tests and characterizat io n,it is found that the diameter of a single nanorod in the array is about 2 0-30nm and the thickness o f the film is 3μm.From the gas sensing test,it is found that the film also has excellent gas sensing response and optima l gas selectivit y to NO ₂ gas:treated with ultravio let light at room temperature,it is found that the gas sensing response o f R2 made o f thin film to 10ppm NO₂ is as high as 4912,the detect ion concentratio n can be as lo w as 100ppb,and the gas sensit ive respo nse value is 1.4,and the response-recover y time is very short and the stabilit y is general.