Preparation Of Inactive Thin-Film Modified ZnO Nanorod Arrays And Their H₂S Sensing Properties

Detection and monitoring of toxic gases in air has been paid more attention because the environmental problems became more and more prominent.H₂S,as a main pollutant,yields wildly in our living and production process.Human exposure to H₂S gas at a low concentration is likely to result in neurobehavioral toxicity and may even cause asphyxia.Hence,design of practical H₂S senor has great scientific and practical significance.Oxide semiconductor-based sensors attract scientist' interests for its easy preparation,low cost,miniaturization and portability.However,the reaction between oxides and acid H₂S seriously impeded the application of oxide semiconductor-based sensors in H₂S detection.In order to overcome this defect,we design an ultra-thin film on oxide nanomaterial,which allow the penetration of electrons but not H₂S molecules.SiO₂ thin film was successfully prepared on ZnO nanorods surface via hydrolysis approach.The effect of film thickness on the H₂S sensing property was studied.Our results demonstrates that a repeatable response was realized on ZnO@SiO₂ nanorods with shell thickness of 1³ nm.The sensitivity of ZnO@SiO₂ nanorods with 1nm shell thickness were 11.2 and 2.63 to 1 ppm and 100 ppb H₂S,respectively.This device was stably used during working temperature of 25³00?.A detailed characterization of ZnO@SiO₂ nanorods was performed by XRD?SEM?TEM?EDS et.al,and the sensing mechanism of ZnO@SiO₂ composite nanostructure to H₂S was proposed to understand its outstanding response performance.Polyvinylpyrrolidone?PVP?film was also used to protect ZnO nanorods for synthesis ZnO@PVP composite nanostructure.Effect of PVP concentration and treatment time on the H₂S sensing property of ZnO nanorods was investigated.Sensor device made of ZnO nanorods treated in 1mmol/L PVP for 3h showed a stable repeatability detection of H₂S at room temperature.Its sensitivity was about 5.5 to 1 ppm H₂S.Stable detection of H₂S was successfully realized by surface modification of ZnO nanorods.The fabricated devices had potential application in H₂S sensors.