辐照改性银掺杂TiO_2纳米管催化紫外光降解乙烯效果
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摘要
为了解辐照改性银掺杂二氧化钛纳米管阵列(titanium dioxide nanotube arrays,TNTAs)半导体材料对光催化降解冷藏环境中乙烯的影响,该文首先通过阳极氧化法制备TNTAs,后用60Co-γ射线对TNTAs进行辐照改性,再用辐照还原技术制备纳米银颗粒,最后用纳米银掺杂制备TNTAs-Ag光催化材料。利用场发射扫描电镜(field emission scanning electron microscope)、X-射线衍射(X-ray diffraction)、X-射线光电子能谱(X-ray photoelectron spectroscopy)对半导体材料表征,结果表明:辐照能把无定型TNTAs转化为锐钛矿晶型,随辐照剂量提高,锐钛矿晶型衍射峰越来越尖锐,晶粒尺寸渐趋减小;TNTAs表面掺银后,银粒子以团簇形式沉积于TNTAs管口处,并未进入管壁内部。在模拟园艺产品冷藏环境中,进行紫外光催化降解乙烯研究,结果表明:辐照剂量为20 k Gy时,降解效果达最优,速率常数K′为2.03×10?4 min?1;纳米Ag引入后,TNTAs-Ag速率常数K′可达5.88×10?4 min?1,与未掺杂仅辐照的TNTAs相比提高了189.66%。
Fruits and vegetables can produce large amounts of ethylene when stored in an enclosed storage space after harvest,which can accelerate the maturity and aging of fruits and vegetables. Due to the existence of ethylene in closed storage environment and inappropriate storage methods, a large amount of horticultural products is deteriorated, resulting in huge economic losses every year. Because of large surface area, stable chemical property, excellent charge transport characteristic and available recycling properties, Ti O2 nanotube arrays(TNTAs) have been used widely in sensors, dye-sensitized solar cells,light catalytic cracking water into hydrogen, degradation of organic pollutants and other related fields. Even though the formation of TNTAs are highly ordered and vertical growth on titanium substrate, the recombination of photo-generated electrons and hole pairs at the surface of TNTAs is an issue, which seriously limits the catalytic efficiency for ethylene degradation. In order to study the influence of semiconductor materials of titanium dioxide nanotube arrays modified with Ag-doped and 60 Co γ-ray irradiation on photocatalytic degradation of ethylene in cold storage environment, we prepared TNTAs with anodic oxidation method followed with60 Co γ-ray irradiated on it for modification. Anodic oxidation method can be used to prepare titanium dioxide nanotube arrays with different dimensions conveniently through controlling anode potential, electrolyte concentration, and temperature, which have been considered as one of the most popular ways for enhancing the photocatalytic efficiency of TiO 2. Gamma rays have been observed to play a key role in inducing disruption and dislodgement of electrons and sometimes atoms within a crystal to create defects in the crystal structure. After the formation of TNTAs, silver nanoparticles were made by irradiated reduction technology and doped on TNTAs to make up the new photocatalytic material of TNTAs-Ag. The addition of Ag nanoparticles can make photo-generated electrons transfer from a higher energy level of TiO 2 to the noble metal with a lower Fermi level so that the electrons and holes can be separated rapidly.Field emission scanning electron microscope(FESEM), X-ray diffraction(XRD), and X-ray photoelectron spectroscopy(XPS) were used to analyze the characterization of the prepared semiconductor materials. Results showed that:irradiated modification can transfer amorphous crystal of TNTAs to anatase crystal. The diffraction peak of anatase crystal becomes more and more sharp and the crystal dimension becomes smaller and smaller with the increase of irradiation dose,indicating that silver particles adhered to the nozzle of TNTAs in the form of cluster deposition and it didn't not enter internal wall after doping the surface of TNTAs. Experiments of photocatalytic degradation of ethylene with TNTAs and TNTAs-Ag under ultraviolet in simulating cold storage environment were also conducted, where rate constant K′ was chosen to represent the degradation ability of ethylene. It turned out that: optimal rate constant K′ can reach up to 2.03×10-4 min-1 when TNTAs were irradiated under 20 kG y. After modifying Ag on irradiated TNTAs, the rate constant K′ increased by 189.66% compared with irradiated modification separately, the constant was 5.88×10-4 min-1.
Fruits and vegetables can produce large amounts of ethylene when stored in an enclosed storage space after harvest,which can accelerate the maturity and aging of fruits and vegetables. Due to the existence of ethylene in closed storage environment and inappropriate storage methods, a large amount of horticultural products is deteriorated, resulting in huge economic losses every year. Because of large surface area, stable chemical property, excellent charge transport characteristic and available recycling properties, Ti O2 nanotube arrays(TNTAs) have been used widely in sensors, dye-sensitized solar cells,light catalytic cracking water into hydrogen, degradation of organic pollutants and other related fields. Even though the formation of TNTAs are highly ordered and vertical growth on titanium substrate, the recombination of photo-generated electrons and hole pairs at the surface of TNTAs is an issue, which seriously limits the catalytic efficiency for ethylene degradation. In order to study the influence of semiconductor materials of titanium dioxide nanotube arrays modified with Ag-doped and 60 Co γ-ray irradiation on photocatalytic degradation of ethylene in cold storage environment, we prepared TNTAs with anodic oxidation method followed with60 Co γ-ray irradiated on it for modification. Anodic oxidation method can be used to prepare titanium dioxide nanotube arrays with different dimensions conveniently through controlling anode potential, electrolyte concentration, and temperature, which have been considered as one of the most popular ways for enhancing the photocatalytic efficiency of TiO 2. Gamma rays have been observed to play a key role in inducing disruption and dislodgement of electrons and sometimes atoms within a crystal to create defects in the crystal structure. After the formation of TNTAs, silver nanoparticles were made by irradiated reduction technology and doped on TNTAs to make up the new photocatalytic material of TNTAs-Ag. The addition of Ag nanoparticles can make photo-generated electrons transfer from a higher energy level of TiO 2 to the noble metal with a lower Fermi level so that the electrons and holes can be separated rapidly.Field emission scanning electron microscope(FESEM), X-ray diffraction(XRD), and X-ray photoelectron spectroscopy(XPS) were used to analyze the characterization of the prepared semiconductor materials. Results showed that:irradiated modification can transfer amorphous crystal of TNTAs to anatase crystal. The diffraction peak of anatase crystal becomes more and more sharp and the crystal dimension becomes smaller and smaller with the increase of irradiation dose,indicating that silver particles adhered to the nozzle of TNTAs in the form of cluster deposition and it didn't not enter internal wall after doping the surface of TNTAs. Experiments of photocatalytic degradation of ethylene with TNTAs and TNTAs-Ag under ultraviolet in simulating cold storage environment were also conducted, where rate constant K′ was chosen to represent the degradation ability of ethylene. It turned out that: optimal rate constant K′ can reach up to 2.03×10-4 min-1 when TNTAs were irradiated under 20 kG y. After modifying Ag on irradiated TNTAs, the rate constant K′ increased by 189.66% compared with irradiated modification separately, the constant was 5.88×10-4 min-1.
引文
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[9]尹奎.γ-辐照对半导体纳米材料的改性研究[D].苏州:苏州大学,2014.Yin Kui.The Investigation on The Modification of Semiconductor nano materials By Gamma Ray Irradiation[D].Su Zhou:Soochow University,2014
[10]Takeda Kazuhiko,Fujiwara Kitao.Characteristics on the determination of dissolved organic nitrogen compounds in natural waters using titanium dioxide and platinized titanium dioxide mediated photocatalytic degradation[J].Water Research,1996,30(2):323-330.
[11]刘董,李钦雨,全晓,等.Ag掺杂Ti O2纳米管阵列光催化性能的研究进展[J].材料导报,2012(S2):50-52.Liu Dong,Li Qinyu,Quan Xiao,et al.Research progress on photocatalytic properties of Ag doped TiO 2 nanotube arrays[J].Materials Review,2012(S2):50-52.(in Chinese with English abstract)
[12]Ye Shengying,Shen Shengwen,Ye Lumeng,et al.Enhancement of the photoelectrocatalytic activity of TiO 2/ACF for ethylene removal by Ag nanoparticles synthesized byγ-ray radiolysis[J].Materials Science in Semiconductor Processing,2014,27:397-403.
[13]Wang Kuohua,Tsai Hunghuan,Hsieh Yunghsu.The kinetics of photocatalytic degradation of trichloroethylene in gas phase over TiO 2 supported on glass bead[J].Applied Catalysis B:Environmental,1998,17(4):313-320.
[14]叶盛英,贺明书,岑超平,等.Ti O2纳米粒子气固相光催化降解乙烯初探[J].农业工程学报,2005,21(5):166-169.Ye Shengying,He Mingshu,Cen Chaoping,et al.Application of gas-solid heterogeneous photocatalytic reaction of nanoparticle Ti O2 to ethylene degradation[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CASE),2005,21(5):166-169.(in Chinese with English abstract)
[15]邹俐辉.碳纳米管-二氧化钛-壳聚糖光催化降解苯的数值模拟[D].长沙:湖南大学,2011.Zou Lihui.Numerical Simulation of the Performance to Degrade Benzene Bytitanium Dioxide-Carbon NanotubesChitosan Film[D].Changsha:Hunan University,2011.
[16]张学军,张光富,金辉霞,等.N,Co共掺杂锐钛矿相TiO 2光催化剂的第一性原理研究[J].物理学报,2013(1):377-384.Zhang Xuejun,Zhang Guangfu,Jin Huixia,et al.Firstprinciples study on anatase Ti O2 photocatalyst codoped with nitrogen and cobalt[J].Acta Phys Sin,2013(1):377-384.(in Chinese with English abstract)
[17]徐惠,徐增辉,刘超,等.PANI/Ag-Ti O2纳米纤维复合材料的制备及其抗菌性能研究[J].稀有金属材料与工程,2011,40(4):749-752.Xu Hui,Xu Zenghui,Liu Chao,et al.Preparation and antibacterial activity of PANI/Ag-TiO 2 fibrous nanocomposites[J].Rare Metal Materials and Engineering,2011,40(4):749-752.(in Chinese with English abstract)
[18]Braginsky L.Interband light absorption at a rough interface[J].Physica E:Low-dimensional Systems and Nanostructures,1999,5(3):142-152.
[19]廖斌,梁宏,张旭,等.光化学沉积Ag纳米颗粒改性二氧化钛纳米管阵列的光催化及光电响应能力研究[J].北京师范大学学报:自然科学版,2011,47(2):154-158.Liao Bin,Liang Hong,Zhang Xu,et al.Photo-electric and photo decompositionability of titaniananotubecovered with Ag metal particles by photo-chemical deposition method[J].Journal of Beijing Normal University:Natural Science,2011,47(2):154-158.(in Chinese with English abstract)
[20]康宏平.银掺杂纳米Ti O2与负载活性炭的制备、表征及可见光催化性能研究[D].武汉:武汉理工大学,2014.Kang Hongping.Preparation,Characterization and Visible Photocatalytic Properties of Silver[D].Wu Han:Wuhan University of Technology,2014.
[21]Ye Shengying,Fang Yichao,Song Xianliang,et al.Decom position of ethylene in cold storage by plasma-assisted photocatalyst process with Ti O2/ACF-based photocatalyst prepared by gamma irradiation[J].Chemical Engineering Journal,2013,225:499-508.
[2]张华峰,张宾,陈天华,等.乙烯生物合成基因工程在果蔬保鲜中的应用[J].生物技术,2005(6):80-82.Zhang Huafeng,Zhang Bin,Chen Tianhua,et al.Application of genetic engineering on ethylene biosynthesis to fruits and vegetables storage[J].Biotechnology,2005(6):80-82.(in Chinese with English abstract)
[3]穆师洋,胡文忠,姜爱丽,等.乙烯的信号分子作用及其在采后果蔬生理代谢调控的研究进展[J].食品工业科技,2015(3):375-378.Mu Shiyang,Hu Wenzhong,Jiang Aili,et al.Research progress in the role of ethylene as signal molecule and regulation of physiological metabolism in postharvest fruits and vegetables[J].Science and Technology of Food Industry,2015(3):375-378.(in Chinese with English abstract)
[4]刘非拉,肖鹏,周明,等.二氧化钛纳米管阵列的制备、改性及应用[J].无机化学学报,2012(5):861-872.Liu Feila,Xiao Peng,Zhou Ming,et al.Preparation,modification and application of Ti O2 nanotube arrays[J].Chinese Journal of Inorganic Chemistry,2012(5):861-872.(in Chinese with English abstract)
[5]杨娟,戴俊,缪娟.Ti O2纳米管阵列的制备及其应用研究进展[J].化工时刊,2008,22(9):56.Yang Juan,Dai Jun,Mou Juan.Research progress of preparation and application of Ti O2 nanotube arrays[J].Chemical Industry Times,2008,22(9):56.(in Chinese with English abstract)
[6]沈生文,叶盛英,宋贤良,等.60Co-γ辐照改性银掺杂纳米Ti O2及光催化降解乙烯[J].农业工程学报,2012(9):236-241.Shen Shengwen,Ye Shengying,Song Xianliang,et al.Photocatalysis degradation of ethylene withγ-ray iaradiated modified silver-doped Ti O2[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CASE),2012(9):236-241.(in Chinese with English abstract)
[7]Neppolian Bernaurdshaw,Bruno Andrea,Bianchi Claudia L,et al.Graphene oxide based Pt-Ti O2 photocatalyst:Ultrasound assisted synthesis,characterization and catalytic efficiency[J].Ultrasonics Sonochemistry,2012,19(1):9-15.
[8]杨俊丽,乔勇进,王海宏,等.高能电子束与60Coγ射线对大蒜辐照保鲜效果的比较研究[J].食品科学,2010(12):260-265.Yang Junli,Qiao Yongjin,Wang Haihong,et al.Comparative study of the effects of high energy electron beam and 60Coγ-ray irradiation on the sprout inhibition and fresh-keeping of garlic[J].Food Science,2010(12):260-265.(in Chinese with English abstract)
[9]尹奎.γ-辐照对半导体纳米材料的改性研究[D].苏州:苏州大学,2014.Yin Kui.The Investigation on The Modification of Semiconductor nano materials By Gamma Ray Irradiation[D].Su Zhou:Soochow University,2014
[10]Takeda Kazuhiko,Fujiwara Kitao.Characteristics on the determination of dissolved organic nitrogen compounds in natural waters using titanium dioxide and platinized titanium dioxide mediated photocatalytic degradation[J].Water Research,1996,30(2):323-330.
[11]刘董,李钦雨,全晓,等.Ag掺杂Ti O2纳米管阵列光催化性能的研究进展[J].材料导报,2012(S2):50-52.Liu Dong,Li Qinyu,Quan Xiao,et al.Research progress on photocatalytic properties of Ag doped TiO 2 nanotube arrays[J].Materials Review,2012(S2):50-52.(in Chinese with English abstract)
[12]Ye Shengying,Shen Shengwen,Ye Lumeng,et al.Enhancement of the photoelectrocatalytic activity of TiO 2/ACF for ethylene removal by Ag nanoparticles synthesized byγ-ray radiolysis[J].Materials Science in Semiconductor Processing,2014,27:397-403.
[13]Wang Kuohua,Tsai Hunghuan,Hsieh Yunghsu.The kinetics of photocatalytic degradation of trichloroethylene in gas phase over TiO 2 supported on glass bead[J].Applied Catalysis B:Environmental,1998,17(4):313-320.
[14]叶盛英,贺明书,岑超平,等.Ti O2纳米粒子气固相光催化降解乙烯初探[J].农业工程学报,2005,21(5):166-169.Ye Shengying,He Mingshu,Cen Chaoping,et al.Application of gas-solid heterogeneous photocatalytic reaction of nanoparticle Ti O2 to ethylene degradation[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CASE),2005,21(5):166-169.(in Chinese with English abstract)
[15]邹俐辉.碳纳米管-二氧化钛-壳聚糖光催化降解苯的数值模拟[D].长沙:湖南大学,2011.Zou Lihui.Numerical Simulation of the Performance to Degrade Benzene Bytitanium Dioxide-Carbon NanotubesChitosan Film[D].Changsha:Hunan University,2011.
[16]张学军,张光富,金辉霞,等.N,Co共掺杂锐钛矿相TiO 2光催化剂的第一性原理研究[J].物理学报,2013(1):377-384.Zhang Xuejun,Zhang Guangfu,Jin Huixia,et al.Firstprinciples study on anatase Ti O2 photocatalyst codoped with nitrogen and cobalt[J].Acta Phys Sin,2013(1):377-384.(in Chinese with English abstract)
[17]徐惠,徐增辉,刘超,等.PANI/Ag-Ti O2纳米纤维复合材料的制备及其抗菌性能研究[J].稀有金属材料与工程,2011,40(4):749-752.Xu Hui,Xu Zenghui,Liu Chao,et al.Preparation and antibacterial activity of PANI/Ag-TiO 2 fibrous nanocomposites[J].Rare Metal Materials and Engineering,2011,40(4):749-752.(in Chinese with English abstract)
[18]Braginsky L.Interband light absorption at a rough interface[J].Physica E:Low-dimensional Systems and Nanostructures,1999,5(3):142-152.
[19]廖斌,梁宏,张旭,等.光化学沉积Ag纳米颗粒改性二氧化钛纳米管阵列的光催化及光电响应能力研究[J].北京师范大学学报:自然科学版,2011,47(2):154-158.Liao Bin,Liang Hong,Zhang Xu,et al.Photo-electric and photo decompositionability of titaniananotubecovered with Ag metal particles by photo-chemical deposition method[J].Journal of Beijing Normal University:Natural Science,2011,47(2):154-158.(in Chinese with English abstract)
[20]康宏平.银掺杂纳米Ti O2与负载活性炭的制备、表征及可见光催化性能研究[D].武汉:武汉理工大学,2014.Kang Hongping.Preparation,Characterization and Visible Photocatalytic Properties of Silver[D].Wu Han:Wuhan University of Technology,2014.
[21]Ye Shengying,Fang Yichao,Song Xianliang,et al.Decom position of ethylene in cold storage by plasma-assisted photocatalyst process with Ti O2/ACF-based photocatalyst prepared by gamma irradiation[J].Chemical Engineering Journal,2013,225:499-508.