常压射频等离子体沉积TiO_2纳米晶颗粒薄膜的气相反应影响因素分析
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摘要
采用常压射频等离子体增强化学气相沉积法(AP-PECVD)制备了TiO_2纳米晶颗粒薄膜,研究了不同等离子体滞留时间下气相反应对沉积过程的影响.采用发射光谱(OES)测量拟合了等离子体的电子温度Te约为32 492.6K、离子温度Ti约为850K,采用热电偶(TC)在线测量等离子体外电极温度T约为662K;由于沉积所获样品为TiO_2锐铁矿晶型,认为等离子体气相温度为662~850K,主要受功率密度的影响.外加电压和电流的研究结果表明,放电形式为等离子体容性耦合辉光放电.采用场发射扫描电子显微镜(FESEM)、高分辨透射电子显微镜(HRTEM)、X射线衍射(XRD)、拉曼(Raman)等测量了沉积薄膜的形貌和结构,分析后发现:当反应气体在等离子体相滞留时间仅为27ns时,沉积的薄膜就开始出现明显的锐钛矿相TiO_2结晶结构,并均为粒径10nm左右的纳米颗粒组成的薄膜;同时随着滞留时间的增加,结晶度增加,薄膜的形貌由分离的纳米团簇变为由锐钛矿纳米颗粒连接的多孔均匀薄膜.研究结果对快速制备多孔锐钛矿TiO_2纳米晶颗粒薄膜有重要的指导意义.
TiO_2 nanocrystalline thin films were prepared by radio frequency atmospheric pressure plasma enhanced chemical vapor deposition(AP-PECVD).The effect of gas phase reaction on the deposition process under different residence time in plasma discharge zone was studied.The plasma electron temperature is about 32492.6 K and ion temperature is about 850 K according to the analysis of the optical emission spectrum(OES).The plasma external electrode temperature is about 662 K measured through thermoelectric couple(TC)and determined mainly by power density. The depositiontemperature is therefore estimated to be 662-850 K considering that pure anatase TiO_2 product film should be formed below 850 K.The glow discharge mode is verified by discharge current and voltage study results.The morphology and structure of the deposited films were measured by field emission scanning electron microscopy(FESEM),high resolution transmission electron microscopy(HRTEM),X-ray diffraction(XRD)and Raman.The analysis shows that anatase TiO_2 nanocrystalline thin films composed of about 10 nm nanoparticles is formed when the residence time of reactive gas in the plasma region is only 27 ns.As the increase of the gas residence time in plasma region,the crystallinity of the film increases.At the same time,the film morphology changes from separated nanoparticulate clusters into porous uniform film closely connected by anatase nanoparticles.This result is practically significant for fast preparation of porous anatase TiO_2 nanocrystalline thin films.
TiO_2 nanocrystalline thin films were prepared by radio frequency atmospheric pressure plasma enhanced chemical vapor deposition(AP-PECVD).The effect of gas phase reaction on the deposition process under different residence time in plasma discharge zone was studied.The plasma electron temperature is about 32492.6 K and ion temperature is about 850 K according to the analysis of the optical emission spectrum(OES).The plasma external electrode temperature is about 662 K measured through thermoelectric couple(TC)and determined mainly by power density. The depositiontemperature is therefore estimated to be 662-850 K considering that pure anatase TiO_2 product film should be formed below 850 K.The glow discharge mode is verified by discharge current and voltage study results.The morphology and structure of the deposited films were measured by field emission scanning electron microscopy(FESEM),high resolution transmission electron microscopy(HRTEM),X-ray diffraction(XRD)and Raman.The analysis shows that anatase TiO_2 nanocrystalline thin films composed of about 10 nm nanoparticles is formed when the residence time of reactive gas in the plasma region is only 27 ns.As the increase of the gas residence time in plasma region,the crystallinity of the film increases.At the same time,the film morphology changes from separated nanoparticulate clusters into porous uniform film closely connected by anatase nanoparticles.This result is practically significant for fast preparation of porous anatase TiO_2 nanocrystalline thin films.
引文
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[2]KLEFFMANN J.Field study of air purification paving elements containing TiO2[J].Atmospheric Environment,2016,129:95-97.
[3]ZHAO J,YANG X D.Photocatalytic oxidation for indoor air purification:A literature review[J].Building and Environment,2003,38(5):645-654
[4]OCHIAI T,TAGO S,HAYASHI M,et al.TiO2-Impregnated porous silica tube and its application for compact air-and waterpurification units[J].Catalysts,2015,5(3):1498-1506.
[5]STAFFORD U,GRAY K A,KAMAT P V.Photocatalytic degradation of organic contaminants:Halophenols and related model compounds[J].Heterogeneous Chemistry Reviews,1996,3(2):77-104.
[6]ENESCA A,BANETO M,PERNIU D,et al.Solar-activated tandem thin films based on CuInS2,TiO2and SnO2in optimized wastewater treatment processes[J].Applied Catalysis BEnvironmental,2016,186:69-76.
[7]PELAEZ M,NOLAN N T,PILLAI S C,et al.A review on the visible light active titanium dioxide photocatalysts for environmental applications[J].Applied Catalysis BEnvironmental,2012,125:331-349.
[8]CHEN J S,LIU M C,ZHANG L,et al.Application of nano TiO2towards polluted water treatment combined with electrophotochemical method[J].Water Res,2003,37(16):3815-3820
[9]YEMMIREDDY V K,HUNG Y C.Selection of photocatalytic bactericidal titanium dioxide(TiO2)nanoparticles for food safety applications[J].LWT-Food Science and Technology,2015,61(1):1-6.
[10]WANG H F,WANG Z Q,HONG H X,et al.Preparation of cerium-doped TiO2 film on 304 stainless steel and its bactericidal effect in the presence of sulfate-reducing bacteria(SRB)[J].Materials Chemistry and Physics,2010,124(1):791-794.
[11]FUJISHIMA A,HONDA K.Electrochemical photolysis of water at a semiconductor electrode[J].Nature,1972,238(5358):37-38
[12]PAVASUPREE S,DUBAS S T,RANGKUPAN R.Surface modification of polypropylene non-woven fibers with TiO2nanoparticles via layer-by-layer self assembly method:Preparation and photocatalytic activity[J].Journal of Environmental Sciences,2015,37:59-66.
[13]DIEBOLD U.The surface science of titanium dioxide[J].Surface Science Reports,2003,48(5/6/7/8):53-229.DOI:10.1016/S0167-5729(02)00100-0
[14]ZHANG J,XU Q,FENG Z C,et al.Importance of the relationship between surface phases and photocatalytic activity of TiO2[J].Angewandte Chemie(International Edition),2008,47(9):1766-1769.
[15]PAN J,LIU G,LU G Q,et al.On the true photoreactivity order of{001},{010},and{101}facets of anatase TiO2crystals[J].Angewandte Chemie,2011,123(9):2181-2185.
[16]XIANG Q,YU J,WANG W,et al.Nitrogen self-doped nanosized TiO2sheets with exposed{001}facets for enhanced visible-light photocatalytic activity[J].Chemical Communications,2011,47(24):6906-6908.
[17]TIAN H Y,ZHAO G H,ZHANG Y N,et al.Hierarchical(001)facet anatase/rutile TiO2 heterojunction photoanode with enhanced photoelectrocatalytic performance[J].Electrochimica Acta,2013,96:199-205.
[18]JIN Z,MENG F L,JIA Y,et al.Porous TiO2 nanowires derived from nanotubes:Synthesis,characterzation and their enhanced photocatalytic properties[J].Microporous and Mesoporous Materials,2013,181:146-153.
[19]SELLONI A.Crystal growth:anatase shows its reactive side[J].Nature Mater,2008,7(8):613-615.
[20]HUANG J R,REN H B,LIU X S,et al.Facile synthesis of porous TiO2 nanospheres and their photocatalytic properties[J].Superlattices and Microstructures,2015,81:16-25.
[21]李岩,徐绍魁,徐金洲,等.常压等离子体增强化学气相沉积纳米晶TiO2多孔薄膜的研究[J].东华大学学报(自然科学版),2009,35(1):108-113.
[22]刘伟,李岩,张菁.偏压对低气压等离子体增强化学气相沉积TiO2薄膜的结构和性能的影响[J].东华大学学报(自然科学版),2009,35(1):103-107.
[23]WANG D X,YANG Q Y,GUO Y,et al.One step growth of TiO2crystal trees by atmospheric pressure plasma jet[J].Materials Letters,2011,65(15/16):2526-2529.
[24]HAHN T D,WIESE W L.Atomic transition probability ratios between some Ar I 4s-4p and 4s-5p transitions[J].Phys Rev,1990,42(9):5747-5749.
[25]WIESE W L,BRAULT J W,DANZMANN K,et al.Unified set of atomic transition probabilities for neutral argon[J].Phys Rev A,1989,39(5):2461-2471.
[26]尹增谦,董丽芳,柴志方,等.氩气介质阻挡放电的发光特性[J].光谱学与光谱分析,2003,23(5):840-842.
[27]曲长红,付乌有,杨海滨.金红石型纳米TiO2颗粒的制备及其光催化性质[J].吉林大学学报(理学版),2009,47(4):811-814.
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