| SnO2is a kind of semiconducting metal oxides which has high sensitivity andhas been widely applied in industry. The continuing research on it has been developedin depth. Along with the in-depth study, the research hotspot focuses on the field ofSnO2nano-material synthesis and its gas sensitive properties. However, the study ismore focused on the three dimensional nanoscale preparation. The preparation ofSnO2nanowires has been reported through a lot of literatures, but there are manydisadvantages of the methods for preparation of SnO2nanowires, such as high energyconsumption, not suitable for mass production, etc. Therefore, it not only hastheoretical significance, but also has high potential application value to explore a kindof new method for synthesis of SnO2nanowires which has the advantages of low cost,low energy consumption, simple technics, and is suitable for large-scale production.The main content of this article is about preparing SnO2nanowires using themethod of organic solvent synthesis with SnC2O4as tin source and ethylene glycol assolvent, analyzing the influencing factors of SnO2morphology, getting the bestcondition by use of this method for the preparation of SnO2nanowires to achieve thegoal of control SnO2morphology. The synthetic mechanism of SnO2nanowires and abrief analysis of gas sensitive performance of SnO2are studied in the end. The mainpoints are as follows:(1) Based on the analysis of the impact of reaction temperature on SnO2morphology, the reaction temperature range of formation of SnO2nanowires wasdetermined between140and177℃. In this range of temperature, the diameter ofSnO2nanowires decreases with the increase of temperature. On the analysis of theinfluence of reaction time on SnO2morphology, we found that the quantity and thediameter of SnO2nanowires increased with time between0and3h. When thereaction time reached to3h, the quantity of nanowires gradually stabilized. As thereaction continued, the diameter size will continue to increase, at the same time, the gathered phenomenon is more serious. Based on the analysis of the effects ofsurfactants on SnO2morphology, we chose the SDS, CATB and PVP as surfactants.Through the analysis, we found that SnO2morphology was more uniform and smallerby adding the surfactant PVP and the diameter of SnO2nanowires decreased withPVP quantity increasing within the scope of0to0.5g. Beyond this range, SnO2morphology began to become irregular. Based on the analysis of the influence ofstirring speed on the SnO2morphology, we found that low stirring speed had bettereffect to the growth of good morphology and when the stirring speed was too fast,short rod structure would become dominant in the end of reaction.(2) In this paper, SEM, TEM, TGA, XRD, FT-IR characterization methods wereused to analyze the synthetic mechanism of SnO2nanowires are analyzed. Resultsshowed that the key step was the oligomerization of tin glycolates. This step could bedescribed as that the oxalate groups of SnC2O4were replaced gradually by ethyleneglycol units through the formation of Sn-O-covalent and Sn OH coordinationbonds. As refluxing was continued, the tin glycolates underwent several steps ofintermediate reactions and eventually led to the formation of longer chains, whichcould further self-assemble into nanowires through van der Waals interactions. Aftercalcination by high temperature, its organic group disappeared and nanowiresstructure with unique pore network had formed.(3) Through analysis of the impact of reaction temperature, reaction time,surfactant and stirring speed on the result of the experiment, It was concluded that thebest reaction conditions were as follows: reaction temperature of175℃, reactiontime of3h, PVP of0.5g and stirring speed of500r/min. Under this condition, themorphology of SnO2nanowires was uniform and its diameter was in the range of35to50nm and its length was about2μm.(4) The sensitive performance of gas sensors made of different SnO2morphologywas tested for ethanol gas in this paper. Through analysis of the impact of worktemperature, SnO2morphology and concentration of ethanol on the sensitiveperformance of gas-sensing materials and the response-recovery curves of gas sensormade of SnO2nanowires to different concentrations of alcohol, It was concluded that when compared with nanorods and grain structure, gas sensor made of SnO2nanowires could have the fast response to the measured gas and high sensitivity. For1000ppm ethanol gas, the sensitivity of gas sensor made of nanowires was89,however, that made of nanorods and nanoparticles was42and21, respectively. Thereason was that the grain size of SnO2nanowires is very small and its specific surfacearea was large. In the SnO2nanowires surface and internal structure, there was a largenumber of pore structure, which connected with each other and formed the porenetwork. This network of pores enabled the analyte to access all the surfaces of SnO2nanowires in the sensing unit. |
PDF Full Text Request