| With the development of industrial society,environmental pollution has become more and more prominent,people began to realize the harmfulness of air pollution and monitor toxic harmful as well as flammable and explosive gases through various methods.Among them,gas sensor as a simple structure,easy to be portable and operate sensing equipment has been widely used in the field of gas detection.Among all kinds of sensors,the sensor based on metal oxide semiconductor（MOS）has attracted extensive attention of researchers because of its advantages of simple manufacturing process,good performance,relative stability and high cost performance.In metal oxide semiconductor,semiconductor sensors based on tungsten oxide nanomaterials have been widely developed and applied in the past period of time.Some common gases can be detected by sensors based on tungsten oxide nanomaterials.In addition,there are few reports on the detection of triethylamine（TEA）gas,and there is not enough attention on the detection of triethylamine at low concentration.At the same time,how to quickly detect the concentration of triethylamine is also a problem worth exploring.This paper to detect triethylamine gas as the goal,through different methods to solve the existing triethylamine gas sensor three problems,one is to reduce the working temperature of the sensor,two is to increase the sensor to low concentration of triethylamine response value,three is to speed up the sensor detection speed.The specific research contents are as follows:1.Tungsten oxide nanowires with different mole ratios（at%）were successfully prepared by electrostatic spinning and calcination.The micromorphology and structure of the samples were characterized by X-ray diffrotometry（XRD）,field emission scanning electron microscopy（FESEM）,transmission electron microscopy（TEM）and X-ray photoelectric spectroscopy（XPS）.The results showed that gold nanoparticles with a diameter of about 14nm were uniformly attached to 3.0 at%Au/WO3 nanowires.In addition,the introduction of precious metal gold increased the adsorption oxygen content of the composite.In the subsequent gas sensitivity test,both the gold supported tungsten oxide nanowires and the pure tungsten oxide nanowires showed good selectivity to triethylamine.Compared with the pure tungsten oxide nanowires,the optimal working temperature of triethylamine was reduced by40℃based on 3.0 at%Au/WO3 nanowires.In addition,the response value of 3.0 at%Au/WO3 nanowires to 20 ppm triethylamine（TEA）was 5 times that of pure tungsten oxide nanowires at the optimal operating temperature of each of these materials.Obviously,the introduction of precious metal gold is a very effective method to improve the gas sensitivity of tungsten oxide nanowires to triethylamine2.In order to optimize the performance of Au/WO3 nanowires sensor,Pt/WO3 nanowires with molar ratios of 1.0%,2.0%and 4.0%were successfully prepared by electrostatic spinning method,and the prepared samples were characterized.XRD results showed that the crystallinity of the prepared samples was good.SEM and TEM characterization showed that Pt nanoparticles with uniform quantity were loaded on WO3 nanowires with diameter of 150nm.The experimental results showed that the sensor based on 2.0 at%Pt/WO3 nanowires had the best performance among the three.Compared with Au/WO3,the sensor based on 2.0 at%Pt/WO3 nanowires had the best performance among the three.Compared with Au/WO3,the sensor based on 2.0 at%Pt/WO3 nanowires had the best performance among the three.The response value of 20 ppm TEA was increased from 72.8 to 202,the recovery time was shortened from 238 s to 16 s,and the detection limit was reduced from 500 ppb to 100 ppb.In addition,the sensor had good stability and high selectivity for triethylamine detection.Finally,the reasons for the improvement of Pt to the detection performance of triethylamine based on WO3 nanowires were analyzed combined with the characterization results.3.In order to further optimize the performance of trethylamine gas sensor based on Pt/WO3 nanowires,Pd/WO3 nanowires with mole ratios of 1.0%,2.5%and 6.0%were prepared by electrostatic spinning method,and the samples were characterized.Combined with XRD characterization results,it could be concluded that the product had high crystallinity and part of Pd nanoparticles were doped into the WO3 lattice.SEM and TEM characterization results showed that the three samples with different mole ratios show typical morphology of nanowires,and the nanowires were complete,continuous and uniform in size.The results showed that,compared with Pt/WO3,the sensor based on 2.5 at%Pd/WO3nanowires had the best performance and different characteristics at two different operating temperatures.Compared with 180℃of Pt/WO3,the sensor based on 2.5 at%Pd/WO3nanowires had the best performance.At the same time,the response value to 20 ppm TEA increased from 202 to 1100 nearly 5 times,the response time was shortened from 130 s to 105s and the minimum detection of 10 ppb TEA could be achieved.In addition,the sensor showed fast response and recovery characteristics at 200℃,its response and recovery time to 20 ppm TEA were 67 s and 6 s.Finally,combined with the characterization results and related theories of semiconductor physics,the increase of gas sensitivity of WO3 by Pd was explained. |
