Preparation And Properties Of Nanometer Zinc Oxide-Based Amine-Gas Sensing Materials

As we know,most volatile amines are harmful to humans,plants and the climate.Among them,triethylamine and dimethylamine seriously threaten human health and safety due to their strong toxicity and irritation.Therefore,real-time and effective monitoring of volatile organic amines is extremely important.Metal oxide semiconductor-based gas sensors are of concerns due to their excellent gas sensing performance.Among them,zinc oxide is known as a potential gas sensing material because of its good stability,low cost and controllable morphology.However,zinc oxide-based gas sensors still have problems such as poor selectivity,high operating temperature and low sensitivity.Therefore,improving the gas sensing performance of zinc oxide has always been a research focus in the field of gas sensing.In this paper,to improve the amine gas sensing performance of zinc oxide,zinc oxide with different morphologies was synthesized by different methods,and their performance were improved by controlling morphology and compounding carbon nitride.The effects of zinc oxide morphology,structure and carbon nitride on the gas-sensitive performance of zinc oxide were studied.The specific research contents and conclusions are as follows:(1)Two-dimensional zinc oxide nanonets were synthesized by the oxalic acid-assisted hydrothermal method,and its morphology and performance were systematically studied by changing the synthesis conditions.Morphology evolutions of zinc oxide from three-dimensional flower-like microparticles to two-dimensional nanonets were achieved by simply changing the heat-treatment temperature.Three-dimensionalzinc oxide cagelike spheres and hexagonal prisms were obtained by substitution for oxalic acid with different additives.Two-dimensional zinc oxide nanonets based gas sensor can effectively detect triethylamine,and it exhibits the maximum sensitivity(213.3)on the exposure of 100 ppm triethylamine at 260 ℃.Its transient response time is 1 s and recovery time is only 5 s exposed 300 ppm triethylamine,and the low detection limit is 63 ppb.Therefore,the two-dimensional zinc oxide nanonet can be used as a gas sensing material for efficiently detecting triethylamine.(2)The zinc oxide nanoparticles were synthesized by a hydrothermal method,and the effects of the amount of n-propylamine on its morphology and gas sensing performance were also explored.With the increase in the amount of n-propylamine added,the morphology of zinc oxide changes from nanoparticles to irregular nanosheets,and finally self-assembles into flower-like zinc oxide.Zinc oxide nanoparticles have the best gas sensing performance for dimethylamine detection,and the sensitivity can reaches 29.7 when exposed to 100 ppm of dimethylamine at 160 ℃.It has high selectivity and repeatability toward dimethylamine,and fast responds and recovers in a wide concentration range.Therefore,zinc oxide nanoparticles can be used as an excellent gas sensing material for detecting dimethylamine.(3)Three dimensional elliptical zinc oxide microspheres self assembled from one-dimensional nanowires were synthesized via a facile solvothermal route,and the effects of alkali concentration on the morphology and properties of zinc oxide was studied.The zinc oxide was modified by carbon nitride,and the effect of different amount of carbon nitride on the performance of zinc oxide was investigated.1D structural Zn O can be regulated by changing the alkali concentration,which further controlling the morphology and microstructures of Zn O.Among them,wool ball-like Zn O exhibits superior gas sensing performances toward dimethylamine detection.After adding carbon nitride,the optimal operating temperature is still 140 ℃,and its sensitivity and selectivity are significantly improved.When the carbon nitride’s amount is 10 wt.%,The zinc oxide/carbon nitride-based gas sensor shows the maximum sensitivity to dimethylamine(31.2),which is 2.5 times that of pure zinc oxide.Therefore,zinc oxide decorated with carbon nitride can be used as an excellent sensing material for detecting dimethylamine.Therefore,carbon nitride can effectively improve the sensing performance of zinc oxide for dimethylamine.