球粒状和棒状纳米赤铁矿光电化学特性研究
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摘要
本文以乙二醇为诱导剂通过电化学沉积法成功合成了球粒状及棒状纳米赤铁矿。X射线衍射光谱(XRD)和Raman光谱结果表明,球粒状赤铁矿粒径20±5 nm;棒状赤铁矿截面直径约20 nm,长90±10 nm;二者物相皆为单一均匀的赤铁矿。紫外-可见吸收光谱显示两种赤铁矿在300~550 nm范围内均有较好吸收,Tauc方程计算球粒状和棒状赤铁矿禁带宽度分别为2.00 e V和1.99 e V。Mott-Schottky拟合结果表明1 M KOH溶液体系中,棒状赤铁矿载流子浓度为1.95×1021cm-3,高于球粒状赤铁矿(3.16×1020cm-3)。进一步的光电化学实验表明:0.6 V(vs.Ag/Ag Cl)电势下棒状赤铁矿光照下电流密度较暗电流提升550%,球粒状赤铁矿电流密度提升77%。研究证实,赤铁矿形貌对其半导体特性及光电化学特性有影响,且棒状赤铁矿电极表现出更好的可见光响应特性,具有更佳的光电催化潜力。
In this study, nanosphere and nanorod hematite were synthesized through electrode position, and both were confirmed as the pure and sole phase of hematite by XRD and Raman. Morphological observations by SEM of electrodes showed that the diameter of nanosphere hematite particles was 20 ± 5 nm, and nanorod hematite particles synthesized in eletrolyte containing ethylene glycol had the length of 90 ± 10 nm and the diameter of about 20 nm.They both exhibited significant absorption in the range of 300 ~ 550 nm in the UV-Vis spectroscopy, and the calculated bandgap width for nanosphere and nanorod hematite was 2. 00 e V and 1. 99 e V, respectively. The calculated carrier density for nanospheres was 3. 16 × 1020 cm-3 and that for nanorods was 1. 95 × 1021 cm-3, fitted through Mott-Schottky curves measured in 1 M KOH solution. The results of photoelectrochemical experiments indicated that the current density of nanorods was lifted up to 5. 5 times with illumination compared with that under dark condition under the potential of 0. 6 V( vs. Ag/Ag Cl). Nevertheless, the fact that the current density of nanospheres rose by just about 77% indicated that, although both nanosphere and nanorod hematite exhibited photoelectric response,the nanorods performed a more remarkable capacity in photoelectrocatalysis.
In this study, nanosphere and nanorod hematite were synthesized through electrode position, and both were confirmed as the pure and sole phase of hematite by XRD and Raman. Morphological observations by SEM of electrodes showed that the diameter of nanosphere hematite particles was 20 ± 5 nm, and nanorod hematite particles synthesized in eletrolyte containing ethylene glycol had the length of 90 ± 10 nm and the diameter of about 20 nm.They both exhibited significant absorption in the range of 300 ~ 550 nm in the UV-Vis spectroscopy, and the calculated bandgap width for nanosphere and nanorod hematite was 2. 00 e V and 1. 99 e V, respectively. The calculated carrier density for nanospheres was 3. 16 × 1020 cm-3 and that for nanorods was 1. 95 × 1021 cm-3, fitted through Mott-Schottky curves measured in 1 M KOH solution. The results of photoelectrochemical experiments indicated that the current density of nanorods was lifted up to 5. 5 times with illumination compared with that under dark condition under the potential of 0. 6 V( vs. Ag/Ag Cl). Nevertheless, the fact that the current density of nanospheres rose by just about 77% indicated that, although both nanosphere and nanorod hematite exhibited photoelectric response,the nanorods performed a more remarkable capacity in photoelectrocatalysis.
引文
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Beermann N,Vayssieres L,Lindquist S E,et al.2000.Photoelectrochemical studies of oriented nanorod thin films of hematite[J].Journal of the Electrochemical Society,147(7):2 456~2 461.
Bjoerksten U,Moser J and Graetzel M.1994.Photoelectrochemical studies on nanocrystalline hematite films[J].Chemistry of Materials,6(6):858~863.
Bose S,Jr M F H,Gorby Y A,et al.2009.Bioreduction of hematite nanoparticles by the dissimilatory iron reducing bacterium Shewanella oneidensis MR1[J].Geochimica et Cosmochimica Acta,73(4):962~976.
Cao D,Luo W,Feng J,et al.2014.Cathodic shift of onset potential for water oxidation on a Ti4+doped Fe2O3photoanode by suppressing the back reaction[J].Energy&Environmental Science,7(2):752~759.
Catti M,Valerio G and Dovesi R.1995.Theoretical study of electronic,magnetic,and structural properties of alpha-Fe2O3(hematite)[J].Physical Review B Condensed Matter,51(12):7 441.
Cutting R S,Coker V S,Fellowes J W,et al.2009.Mineralogical and morphological constraints on the reduction of Fe(Ⅲ)minerals by Geobacter sulfurreducens[J].Geochimica et Cosmochimica Acta,73(14):4 004~4 022.
Debnath N C and Anderson A B.1982.Optical-spectra of ferrous and ferric oxides and the passive film-a molecular-orbital study[J].Journal of the Electrochemical Society,129(10):2 169.
Faria Dlad and Lopes F N.2007.Heated goethite and natural hematite:Can Raman spectroscopy be used to differentiate them?[J].Vibrational Spectroscopy,45(2):117~121.
Faria Dlad,Silva S and de Oliveira M.1997.Raman microspectroscopy of some iron oxides and oxyhydroxides[J].Journal of Raman Spectroscopy,28:873~878.
Franking R,Li L,Lukowski M A,et al.2013.Facile post-growth doping of nanostructured hematite photoanodes for enhanced photoelectrochemical water oxidation[J].Energy&Environmental Science,6(2):500~512.
Fu L,Yu H,Li Y,et al.2014.Ethylene glycol adjusted nanorod hematite film for active photoelectrochemical water splitting[J].Physical Chemistry Chemical Physics Pccp,16(9):4 284~4 290.
Guo J.2007.Hematite nanoarrays promise water photo-oxidation by solar irradiation[J].Spie Newsroom,39(8):339.
Hardee K L and Bard A J.1976.Chem Inform Abstract:semiconductor electrodes.V.The application of chemically vapor deposited iron oxide films to photosensitized electrolysis[J].Chemischer Informationsdienst,7(43):1 024~1 026.
Huang X,Hou X,Song F,et al.2016.Facet-dependent Cr(Ⅵ)Adsorption of Hematite Nanocrystals[J].Environmental Science&Technology,50(4):1 964.
Karunakaran C and Senthilvelan S.2006.Fe O-photocatalysis with sunlight and UV light:Oxidation of aniline[J].Electrochemistry Communications,8(1):95~101.
Kato S,Hashimoto K and Watanabe K.2013.Iron-oxide minerals affect extracellular electron-transfer paths of geobacter spp[J].Microbes&Environments,28(1):141.
Kennedy J H and Anderman M.1983.Photoelectrolysis of water atα-Fe2O3electrodes in acidic solution[J].Journal of the Electrochemical Society,130(4).
Kleiman-Shwarsctein A,Huda M N,Walsh A,et al.2009.Electrodeposited aluminum-dopedα-Fe2O3photoelectrodes:experiment and theory[J].Chemistry of Materials,22(2):510~517.
Li C,Wang T,Luo Z,et al.2016.Enhanced charge separation through ALD-Modified Fe2O3/Fe2Ti O5nanorod heterojunction for photoelectrochemical water oxidation[J].Small,12(25):3 415~3 422.
Lu Anhuai,Li Yan,Wang Xin,et al.2014.The photoelectron generation from semiconducting minerals and its effects in critical zone[J].Earth Science Frontiers,21(3):256~264(in Chinese with English abstract).
Lu Anhuai,Lu Xiaoying,Ren Ziping,et al.2000.New advances in environmental mineralogy of natural oxides and hydroxides of iron and manganese[J].Earthence Frontiers,7(2):473~483(in Chinese with English abstract).
Ma Y,Johnson P D,Wassdahl N,et al.1993.Electronic structures ofα-Fe2O3and Fe3O4from O K-edge absorption and emission spectroscopy[J].Phys.Rev.B.,48(4):2 109.
Pankove and Jacques I.1971.Optical Processes in Semiconductors[M].Optical Processes in Semiconductors Prentice-Hall,805~807.
Pawar R C,Pyo Y,Ahn S H,et al.2015.Photoelectrochemical properties and photodegradation of organic pollutants using hematite hybrids modified by gold nanoparticles and graphitic carbon nitride[J].Applied Catalysis B Environmental,176~177(3):654~666.
Praveen Kumar,Poonam Sharma,Rohit Shrivastav,et al.2011.Electrodeposited zirconium-dopedα-Fe O thin film for photoelectrochemical water splitting[J].International Journal of Hydrogen Energy,36(4):2 777~2 784.
Qian F,Wang H,Ling Y,et al.2014.Photoenhanced electrochemical interaction between Shewanella and a hematite nanowire photoanode[J].Nano Letters,14(6):3 688.
Ren G,Ding H,Li Y,et al.2016.Natural hematite as a low-cost and earth-abundant cathode material for performance improvement of microbial fuel cells[J].Catalysts,6(10):157.
Shim,Duffy S H and Thomas S.2002.Raman spectroscopy of Fe2O3to62 GPa[J].American Mineralogist,87(2~3):318~326.
Shinde P S,Go G H and Lee W J.2012.Facile growth of hierarchical hematite(α-Fe2O3)nanopetals on FTO by pulse reverse electrodeposition for photoelectrochemical water splitting[J].Journal of Materials Chemistry,22(21):10 469~10 471.
Sivula K,Zboril R,Le Formal F,et al.2010.Photoelectrochemical water splitting with mesoporous hematite prepared by a solution-based colloidal approach[J].Journal of the American Chemical Society,132(21):7 436.
Spray R L and Choi K S.2009.Photoactivity of transparent nanocrystalline Fe2O3electrodes prepared via anodic electrodeposition[J].Chemistry of Materials,21(15).
Sukhotin A M,Grilikhes M S and Lisovaya E V.1989.The influence of passivation on the kinetics of the dissolution of iron-I.Outer layer of the passivating film as a heavy doped thin semiconductor and mottschottky equation[J].Electrochimica Acta,34(2):109~112.
Theng B K G and Yuan G.2008.Nanoparticles in the soil environment[J].Elements,4(6):395~399.
Velev J,Bandyopadhyay A,Butler W H,et al.2005.Electronic and magnetic structure of transition-metal-doped alpha-hematite[J].Physical Review B.,71(20):5 208.
Wang Xinghong,Li Zhang,Ni Yonghong,et al.2009.Fast preparation,characterization,and property study ofα-Fe2O3nanoparticles via a simple solution-combusting method[J].J.Phys.Chem.C.,113(17):7 003~7 008.
Waychunas G A,Kim C S and Banfield J F.2005.Nanoparticulate iron oxide minerals in soils and sediments:Unique properties and contaminant scavenging mechanisms[J].Journal of Nanoparticle Research,7(4~5):409~433.
Zhu Rui.2011.Extraction,characterization and adsorption of inorganic nanoparticles in soils[D].Zhejiang University(in Chinese with English abstract).
鲁安怀,卢晓英,任子平,等.2000.天然铁锰氧化物及氢氧化物环境矿物学研究[J].地学前缘,7(2):473~483.
鲁安怀,李艳,王鑫,等.2014.关键带中天然半导体矿物光电子的产生与作用[J].地学前缘,21(3):256~264.
朱蕊.2011.土壤中无机纳米颗粒提取、表征及其重金属吸附研究[D].浙江大学.
Beermann N,Vayssieres L,Lindquist S E,et al.2000.Photoelectrochemical studies of oriented nanorod thin films of hematite[J].Journal of the Electrochemical Society,147(7):2 456~2 461.
Bjoerksten U,Moser J and Graetzel M.1994.Photoelectrochemical studies on nanocrystalline hematite films[J].Chemistry of Materials,6(6):858~863.
Bose S,Jr M F H,Gorby Y A,et al.2009.Bioreduction of hematite nanoparticles by the dissimilatory iron reducing bacterium Shewanella oneidensis MR1[J].Geochimica et Cosmochimica Acta,73(4):962~976.
Cao D,Luo W,Feng J,et al.2014.Cathodic shift of onset potential for water oxidation on a Ti4+doped Fe2O3photoanode by suppressing the back reaction[J].Energy&Environmental Science,7(2):752~759.
Catti M,Valerio G and Dovesi R.1995.Theoretical study of electronic,magnetic,and structural properties of alpha-Fe2O3(hematite)[J].Physical Review B Condensed Matter,51(12):7 441.
Cutting R S,Coker V S,Fellowes J W,et al.2009.Mineralogical and morphological constraints on the reduction of Fe(Ⅲ)minerals by Geobacter sulfurreducens[J].Geochimica et Cosmochimica Acta,73(14):4 004~4 022.
Debnath N C and Anderson A B.1982.Optical-spectra of ferrous and ferric oxides and the passive film-a molecular-orbital study[J].Journal of the Electrochemical Society,129(10):2 169.
Faria Dlad and Lopes F N.2007.Heated goethite and natural hematite:Can Raman spectroscopy be used to differentiate them?[J].Vibrational Spectroscopy,45(2):117~121.
Faria Dlad,Silva S and de Oliveira M.1997.Raman microspectroscopy of some iron oxides and oxyhydroxides[J].Journal of Raman Spectroscopy,28:873~878.
Franking R,Li L,Lukowski M A,et al.2013.Facile post-growth doping of nanostructured hematite photoanodes for enhanced photoelectrochemical water oxidation[J].Energy&Environmental Science,6(2):500~512.
Fu L,Yu H,Li Y,et al.2014.Ethylene glycol adjusted nanorod hematite film for active photoelectrochemical water splitting[J].Physical Chemistry Chemical Physics Pccp,16(9):4 284~4 290.
Guo J.2007.Hematite nanoarrays promise water photo-oxidation by solar irradiation[J].Spie Newsroom,39(8):339.
Hardee K L and Bard A J.1976.Chem Inform Abstract:semiconductor electrodes.V.The application of chemically vapor deposited iron oxide films to photosensitized electrolysis[J].Chemischer Informationsdienst,7(43):1 024~1 026.
Huang X,Hou X,Song F,et al.2016.Facet-dependent Cr(Ⅵ)Adsorption of Hematite Nanocrystals[J].Environmental Science&Technology,50(4):1 964.
Karunakaran C and Senthilvelan S.2006.Fe O-photocatalysis with sunlight and UV light:Oxidation of aniline[J].Electrochemistry Communications,8(1):95~101.
Kato S,Hashimoto K and Watanabe K.2013.Iron-oxide minerals affect extracellular electron-transfer paths of geobacter spp[J].Microbes&Environments,28(1):141.
Kennedy J H and Anderman M.1983.Photoelectrolysis of water atα-Fe2O3electrodes in acidic solution[J].Journal of the Electrochemical Society,130(4).
Kleiman-Shwarsctein A,Huda M N,Walsh A,et al.2009.Electrodeposited aluminum-dopedα-Fe2O3photoelectrodes:experiment and theory[J].Chemistry of Materials,22(2):510~517.
Li C,Wang T,Luo Z,et al.2016.Enhanced charge separation through ALD-Modified Fe2O3/Fe2Ti O5nanorod heterojunction for photoelectrochemical water oxidation[J].Small,12(25):3 415~3 422.
Lu Anhuai,Li Yan,Wang Xin,et al.2014.The photoelectron generation from semiconducting minerals and its effects in critical zone[J].Earth Science Frontiers,21(3):256~264(in Chinese with English abstract).
Lu Anhuai,Lu Xiaoying,Ren Ziping,et al.2000.New advances in environmental mineralogy of natural oxides and hydroxides of iron and manganese[J].Earthence Frontiers,7(2):473~483(in Chinese with English abstract).
Ma Y,Johnson P D,Wassdahl N,et al.1993.Electronic structures ofα-Fe2O3and Fe3O4from O K-edge absorption and emission spectroscopy[J].Phys.Rev.B.,48(4):2 109.
Pankove and Jacques I.1971.Optical Processes in Semiconductors[M].Optical Processes in Semiconductors Prentice-Hall,805~807.
Pawar R C,Pyo Y,Ahn S H,et al.2015.Photoelectrochemical properties and photodegradation of organic pollutants using hematite hybrids modified by gold nanoparticles and graphitic carbon nitride[J].Applied Catalysis B Environmental,176~177(3):654~666.
Praveen Kumar,Poonam Sharma,Rohit Shrivastav,et al.2011.Electrodeposited zirconium-dopedα-Fe O thin film for photoelectrochemical water splitting[J].International Journal of Hydrogen Energy,36(4):2 777~2 784.
Qian F,Wang H,Ling Y,et al.2014.Photoenhanced electrochemical interaction between Shewanella and a hematite nanowire photoanode[J].Nano Letters,14(6):3 688.
Ren G,Ding H,Li Y,et al.2016.Natural hematite as a low-cost and earth-abundant cathode material for performance improvement of microbial fuel cells[J].Catalysts,6(10):157.
Shim,Duffy S H and Thomas S.2002.Raman spectroscopy of Fe2O3to62 GPa[J].American Mineralogist,87(2~3):318~326.
Shinde P S,Go G H and Lee W J.2012.Facile growth of hierarchical hematite(α-Fe2O3)nanopetals on FTO by pulse reverse electrodeposition for photoelectrochemical water splitting[J].Journal of Materials Chemistry,22(21):10 469~10 471.
Sivula K,Zboril R,Le Formal F,et al.2010.Photoelectrochemical water splitting with mesoporous hematite prepared by a solution-based colloidal approach[J].Journal of the American Chemical Society,132(21):7 436.
Spray R L and Choi K S.2009.Photoactivity of transparent nanocrystalline Fe2O3electrodes prepared via anodic electrodeposition[J].Chemistry of Materials,21(15).
Sukhotin A M,Grilikhes M S and Lisovaya E V.1989.The influence of passivation on the kinetics of the dissolution of iron-I.Outer layer of the passivating film as a heavy doped thin semiconductor and mottschottky equation[J].Electrochimica Acta,34(2):109~112.
Theng B K G and Yuan G.2008.Nanoparticles in the soil environment[J].Elements,4(6):395~399.
Velev J,Bandyopadhyay A,Butler W H,et al.2005.Electronic and magnetic structure of transition-metal-doped alpha-hematite[J].Physical Review B.,71(20):5 208.
Wang Xinghong,Li Zhang,Ni Yonghong,et al.2009.Fast preparation,characterization,and property study ofα-Fe2O3nanoparticles via a simple solution-combusting method[J].J.Phys.Chem.C.,113(17):7 003~7 008.
Waychunas G A,Kim C S and Banfield J F.2005.Nanoparticulate iron oxide minerals in soils and sediments:Unique properties and contaminant scavenging mechanisms[J].Journal of Nanoparticle Research,7(4~5):409~433.
Zhu Rui.2011.Extraction,characterization and adsorption of inorganic nanoparticles in soils[D].Zhejiang University(in Chinese with English abstract).
鲁安怀,卢晓英,任子平,等.2000.天然铁锰氧化物及氢氧化物环境矿物学研究[J].地学前缘,7(2):473~483.
鲁安怀,李艳,王鑫,等.2014.关键带中天然半导体矿物光电子的产生与作用[J].地学前缘,21(3):256~264.
朱蕊.2011.土壤中无机纳米颗粒提取、表征及其重金属吸附研究[D].浙江大学.