Synthesis and Gas-sensing Performance of Nanosized SnO2

CHEM. RES. CHINESE U. 2005, 21(1),17-20Synthesis and Gas-sensing Performance of Nanosized SnO2WANG Shu-rong, WU Shi-hua.", SHI Juan and ZHENG Xiu-cheng1. Department of Chemistry, Nankai University, Tianjin 300071, P.R. China;2. Inst. Mat. Sci.& Chem. Engn, Tianjin Polytechnic University, Tianjin 300160, P.R. ChinaReceived Oct 9. 2003d tin dioxide particles were prepared by sol-gel dialytic prowith tin(n) chloride aalcohol as start materials, Te nanopticles of tin dioxide were chay thermogravimetry anddifferential thermal analysis(TG-DTA),X-ray diffraction (XRD), transmission electron microscopy(TEM)and BET. The results show that the average diameter of tin dioxide particles dried at 353 K was about 2 nm.Even if the tin dioxide particles were calcined at 873K, the average diameter of particles was less than 10nm. The removal of Cl was solved by using this kind of method. The mechanism of the formation of tindioxide nanosized particles was proposed and analyzed in this paper. We also measured the sensitivity of thesensor based on the tin oxide powder calcined at 673 K to NH;, alcohol, acetone, hexane and CO. The gas-sensing performance results indicate that this sensor has a higher sensitivity to alcohol and acetone, andselectivity for NH;, hexane and CO at an operating temperature of 343 KKeywords Nanosized tin dioxide particle. Sol-gel dialytic process, Mechanism, Gas-sensing performancerticle|D1005-9040(2005)-01-017-04Introductiemoving Cl ions, and introduced a dialyticrenTin dioxide is an n-type semiconductor oxide process to improve and accelerate the formation ofwith a wide energy gap. Owing to the particular the gels. The specimens were charactered by TGphysical aremical propd tin dta, xrd. tem and bet. the results shodioxide, it has covered a wide range of application that tin dioxide particles prepared by the sel-golhmaterial in rechargeable Li batteries, and optical BET surface areas. At the same timee alsoelectronic devices 1-53. The gas-sensing property of increased the purity and the yield of tin dioxidetin dioxide has been studied for a long time and it nanosized particles. The sensitivity of an SnOhas been shown that the gas sensors based on tin sensor to CO, Nh,. hexane, acetone, and alcoholdioxide play an important role in manyover a range of concentration of 1. 0X10-40Xapplications 6-8. Recently, there have been many104 mol/L was measuredmethods for the preparation of nanosized tinExperidioxide, but among them some methods arerestricted due to expensive equipment or numerousI Preparation of Nanosized Tin Dioxide Particleserational procedures. Tin(iv) chloride or tianosized tin dioxide particles were prepared( chloride is usually used as the startingby the sol-gel dialytic process. Tin(N) chloridematerial to prepare nanosized tin dioxide, which was mixed with alcohol to obtain a tin(IV)chlorideresults in a great deal of CI ions in the reactive alcohol solution. The precursor Sn(OC H, ),Colloidsystem. It is well known that Cl ions havesolution was prepared by introducing ammonia gasnegative impact on catalytic activity of tinto the tin(l)chloride alcohol solution at 273 Kdioxide[9, 1o], so the removal of cl- ions becomes an under stirring constantly. After a white precipitateindispensable procedure in the process of the was filtered. the colloid solution was input into thepreparation of nanosized tin dioxide. In this work中国煤化工 pwe used tin(N) chloride and alcohol as the starting WImined by a 0. 1 mol/LlIs, ammonia gas astalyst to the ACNMHGformation of the colloid solution and the agent of was 7, the wet-gels formed in the process ofx Supported by the National Natural Science Foundation of China( No, 20271028)and TiNatural scienceFoundation)穷數2511)Towhomcorrespondenceshouldbeaddressed.E-mail:Jackmxd808@163.com18CHEM. RES CHINESE UVol 21dialysis were dried at 353 K for 24 h. FinallyWe examined the white precipitate filteredsamples were calcined in air at 673 K and 873 K for the result proves that it was ammonium chlorate3 h to obtain different nanometric grain sized tin We also observed the solutions before and afterdioxide particlesammonia gas was introduced into them, and it was2 Characterization of Nanosized Tin Dioxidefound that the former did not show the TyndallThe X-ray diffraction (XRD analyses were phenomenon, but the latter did. And according toperformed on a D/MAX-RAX diffractometer with references 11, 12, we propose that the reaction ofCu Ka radiation scanning range 20: 50%--75) SnCl, with C2h Oh to form an Sn(OC? H), alcoholoperated at 40 kv and 100 mA. The colloid solution might be as followsthermogravimetry and differential thermal analysesNH3+C2HOH→→NH#+C2H2O(1)TG-DTA) were performed with a ZRY-2PSnCl,+ 4NHt-Sn++ 4NH, CI(2)thermal analyser. The thermograms were recordedSn++4C,HOSn(OC2H3)4(3)from ambient temperature to 1173 K at a linear Owing to the existence of ammonia gas, the aboveate of 10 K/min under nitrogen reactive processes were accelerated, and finishedatmosphere flowing at a rate of 40 mL/min. a- only within several minutes, which saved muchAl2O, was used as the reference. The measuringtimeof DTA and TG was 25 V and 10 mgIn the process of the dialysis, the ph of therespectively. The surface area was calculated by dialysate was less than 7, and without precipitationthe BEt method from the nitrogen adsorption- in the dialysate while wet-gel was gradually formeddesorption isotherms(Fig. 1)recorded at 77 K by a in the dialytic membrane. Those indicate that thehembet-3000 physical autosorb. The transmission following hydrolysis reaction of PSn(OC, Helectron microscopy(TEM) study was performedwith a phillips 400 ST transmission electronH3Sn(OC? H)4->Sn(OH)(OC? H )3microscopeSn(Oh),(OC, H)2xgof the dialNHo+CC2Hs)hYodialytic membrane0.00.4户AFig. I Nitrogen adsorption isotherms on nanosized snoSnO2·mH2O5n(o)(Oc2H3)H小Opowders calcined at different temperatures3 Measurement of Gas-sensing PropertiesTo fabricate a thin-film type of sensor devicesFig. 2 The process of the formation of SnO, wet-gelthe SnO2 powder was mixed with an organic carrierIt took about 18 h to form SnO, wet-gel andand a paste was obtained, and then it was circle- washing was not needed. By calculating, we alsoconcluded that the yield of SnO2 was 95% and 94%oated onto an alumina tube attached to a Pt Cl- from SnCl, was transferred into NH CIrode. The sensitivity of sensor to alcoholconsidering the error, this result conformed withacetone, hexane, CO and NHs over a range of thaTA analconcentrations of1.4×10-4-4.0×10-4mol/I中国煤化工balanced with dry air was measured at a constantCNMHGDTA curves of SnO,temperature of 343 K. The sensitivity(3) was dried at 353 K. From Fig 3, we can see that theredefined as the ratio of the sensor resistance in air are only two small peaks at near 388. 5 and 576.8(Ra) to that in a sample gas (Rg)K, corresponding to 3. 1% and 1. 5% losses ofResults数 ussIonmass respectively. The peak at 388.5 K resultsfrom the loss of a small amount absorbed water andThe mechanism of formation of tin dioxideWANG Shu-rong et alalcohol, and the peak at 576.8 K results from theFrom Table 1, it can be seen that both thesublimate of the remained ammonium chlorideincrease of the average diameter and the decrease ofThis analysis showed that the tin dioxide powders the surface area of tin dioxide particles calcined atprepared by the sol-gel dialytic process had formed different temperatures are not very remarkablecrystals by being dried at 353 K for 24 h. The Fig. 5 shows the TEM image of the tin oxideexistence of a small amount of water, alcohol andpowder calcined at 673 K for 3 h, the mean particleammonium chloride in the samples is a normal size of the SnO, powder determined by TEM is 6.5phenomenon, and they could be removed bynm. which is in accordance with the value obtainedheating to above 633 K. The results of the tOfrom the XRD patternDTA analyses are in concordance with those of theXRD analysisDTADTG20Lc的01o10T/KFig 5 TEM image of nanosized SnO2 powderFig 3 TG-DTA curves of Snocalcined at 673K for 3 hFig 4 shows the X-ray patterns of nanosized 3 Gas-sensing PrSnO2 calcined at different temperatures. ComparedFrom Fig. 6, it can be seen that the sensorto JCPDS (41-1445)standard pattern, these xrd based on the powdered tin oxide calcined at 673 Kresults indicate that the samples heated at 353, 673 exhibits a very low sensitivity for NH3, hexane andand 873 K were all single tetragonal systems. From CO, but a good sensitivity for alcohol and acetonethe information provided by the XRD pattern, wecould see that the peaks of the samples are nothe selectivity Alcohol/BNH. =37. 6, Alcohol/Phesharp at a low temperature, but as the temperature 13. 2. Alcohol/co=43. 3. Acetone/BNH, =32. 5, Acetone/was increased, the peaks become more and more Hexane=11. 4, BPco=37. 4. This sensor showsharp. The results show that the particle size of a good selectivity for NH3, hexane and CO. Thethe tin dioxide incrased as the temperature was response time and recovery time(time for 90% ofincreased. The average diameters of particles the total sensitivity change)(Fig. 7)are about 40 streated at different temperatures were calculated by1/L alcohol, 50s and 90 sScherrer equation 13]and are listed in Table 1for the 1 10 mol/L acetone, respectively. The10】time is short enough for the practical use. Therepeat measurement results of gas-sensing873properties are in concordance with those mentionedabove, which indicates this sensor has a goodtabiliR250200F+acetoneFig4 x-ray diffraction patterns of nanosized中国煤化工SnO, treated at various temperatures.CNMHGTable 1 Mean particle size and surface area of tindioxide treated at various temperatures10 xGas concentration/(mol.L-1)D/nmsAm,10H6 ariation in the sensitivity of sensor in sampCHEM. RES CHINESE UVol 21References1×10-6mol· L acetone1×10-6mol· L alcohol[11 Santhosh P N, Potde H. S, Date S.K...Mater.2] Goodman R. D,, Menke A. G,, Solar Engergy, 1995, 17,[3 Salas P, Hemandez J. G., Montoya J. A, et al., Journalof Molecular Catalysis A: Chemical, 1997, 123,14950100150200250300Universities, 2003. 24(9).1544[5 CAO Ya-An, SHEN Dong-Fang, ZHANG Xin Tong, et al.Fig. 7 Response and recovery characteristics of sensorChem, Chinese Universities. 2001. 22(11).1910for 1x104 mol/L alcohol and acetone at an[6 Dal Santos M. A, Antunes A. C, Ribeiro C, et al.,operating temperature of 343 K.Materials letters, 2003. 57. 4378[7 Elisa betta Comini, Vincenzo Guidi, Cesare Malagu, et aL..Phys.Chem.B.,2004,108,1882Conclusions[8]h nDekany L, Suvegh K, et al., LangmNanoparticles of tin dioxide prepared by sol2003,19,3762gel dialytic prossesses with tin(N) chloride[9] Mark A, Bollinger M., Albert V, Applied Catalysis B:alcohol and anomonia gas as the raw materialEnvironmental, 1996.8. 41[10 Patricle G, Michel P, Applied Catalysis B:possess the advantage of small diameters, largeEnvironmental. 2002. 39. 1surface areas, high purity and high production [11] Deng Zhao-Xiang, Wang Cheng, Li Ya-Dong,..Amyields, so they are suitable for being used as theeram.Soc.,2002,S5(11),2837catalysts or catalytic supports. The gas-sensing[12 Wang Cheng. Deng Zhao-Xiang, Zhang Guo-Hui, PowderTechnology, 2002, 25, 39experimental results show that the powdered tin [13] Wu S HW., Huang W. P, Chinese ournal ofxide sensor has a better sensitivity to alcohol and9,4acetone,and has a good stability, which indicatesthe potential application prospects of tin oxides asgas sensors中国煤化工CNMHG