Fe_3O_4/PAMAM/ZnO/TiO_2核-壳结构纳米颗粒的逐层构建及其光催化性能
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摘要
以聚酰胺-胺(PAMAM)树形分子为模板和隔离层采用水热法逐层构建了Fe_3O_4/PAMAM/ZnO/TiO_2和Fe_3O_4/PAMAM/TiO_2核-壳结构纳米颗粒,用HRTEM、EDS、XRD、SQUID和UV-Vis等手段对其结构和性能进行了表征。结果表明,这两种颗粒具有完整清晰的核-壳结构,磁核与壳层均由尺寸小于5 nm的颗粒聚集而成,具有超顺磁性和较高的MB吸附率。PAMAM隔离层降低了Fe_3O_4核与TiO_2壳接触面积,但是残留在界面处的微量Fe~(2+)电子向壳层迁移,导致壳层能隙变窄、吸收光谱红移以及迁入电子与壳层光生空穴复合,使Fe_3O_4/PAMAM/TiO_2的催化活性降低。Fe_3O_4/PAMAM/ZnO/TiO_2中更厚的PAMAM隔离层和ZnO层阻隔了Fe~(2+)电子向TiO_2层迁移,并且ZnO/TiO_2界面异质结构有利于光生电子-空穴对的分离,界面的新电子态使颗粒吸收光谱进一步红移,提高了对可见光的利用率和催化活性。5次磁性回收循环使用后,Fe_3O_4/PAMAM/ZnO/TiO_2的磁性回收率和MB降解率分别为93.8%和90.8%。
Core-shell nanoparticles of Fe_3O_4/PAMAM/ZnO/TiO_2 and Fe_3O_4/PAMAM/TiO_2 were prepared by hydrothermal method with polyamidoamine(PAMAM) as template and isolation layer, while the construction mechanism and performance of which were investigated. The mophology, size, structure and proporties of these particles were characterized by HRTEM, EDS, XRD, SQUID and UV-Vis measurements. The results show that core-shell nanoparticles present clearly structure composed of magnet-ic core and shell, which were stacked with nanoparticles less than 5 nm in diameter, leading to high saturation magnetization and MB-adsorption rates. Althouth the interfacial contact area of core and shell was reduced by PAMAM isolation layer, trace electrons Fe~(2+) at the inerface could migrate into the TiO_2 shell through the residual interfacial contact area, and then combine with the holes in shell, which brought the narrowing of shell band gap and the red-shifting of the absorption spectrum and thus the decreasing of catalytic activity. As for Fe_3O_4/PAMAM/ZnO/TiO_2, the thicker PAMAM and ZnO layers cutted off the way of electrons migration to the TiO_2 shell. The heterogeneous structure of ZnO/TiO_2 facilitated the separation of the photogenerated electron hole pairs in shell. The new interface electronic states brought further redshifting of the the absorption spectrum, higher utilization ratio of visible light, and therewith resulted in higher catalytic activity. The magnetic recovery and MB-degradation rate of Fe_3O_4/PAMAM/ZnO/TiO_2 are 93.8% and 90.8% respectively after being recyced for 5 times.
Core-shell nanoparticles of Fe_3O_4/PAMAM/ZnO/TiO_2 and Fe_3O_4/PAMAM/TiO_2 were prepared by hydrothermal method with polyamidoamine(PAMAM) as template and isolation layer, while the construction mechanism and performance of which were investigated. The mophology, size, structure and proporties of these particles were characterized by HRTEM, EDS, XRD, SQUID and UV-Vis measurements. The results show that core-shell nanoparticles present clearly structure composed of magnet-ic core and shell, which were stacked with nanoparticles less than 5 nm in diameter, leading to high saturation magnetization and MB-adsorption rates. Althouth the interfacial contact area of core and shell was reduced by PAMAM isolation layer, trace electrons Fe~(2+) at the inerface could migrate into the TiO_2 shell through the residual interfacial contact area, and then combine with the holes in shell, which brought the narrowing of shell band gap and the red-shifting of the absorption spectrum and thus the decreasing of catalytic activity. As for Fe_3O_4/PAMAM/ZnO/TiO_2, the thicker PAMAM and ZnO layers cutted off the way of electrons migration to the TiO_2 shell. The heterogeneous structure of ZnO/TiO_2 facilitated the separation of the photogenerated electron hole pairs in shell. The new interface electronic states brought further redshifting of the the absorption spectrum, higher utilization ratio of visible light, and therewith resulted in higher catalytic activity. The magnetic recovery and MB-degradation rate of Fe_3O_4/PAMAM/ZnO/TiO_2 are 93.8% and 90.8% respectively after being recyced for 5 times.
引文
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[17]Shaheen B S, Salem H G, El-Sayed M A, et al. Thermal/electrochemical growth and characterization of one-dimensional ZnO/TiO2hybrid nanoelectrodes for solar fuel production[J]. J. Phys.Chem. C, 2013, 117:18502
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[19]Chang J, Kuga Y, Mora-Sero Y, et al. High reduction of interfacial charge recombination in colloidalquantum dot solar cells by metal oxide surface passivation[J]. Nanoscale, 2015, 7:5446
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[23]Kwiatkowski M, Bezverkhyy I, Skompska M. ZnO nanorods covered with aTiO2layer:simple sol-gel preparation, and optical, photocatalytic andphotoelectrochemical properties[J]. J. Mater. Chem A. 2015, 3:12748
[24]Watson S, Beydoun D, Amal R S. Synthesis of a novel magnetic photocatalyst by direct deposition of nanosized TiO2crystals onto a magnetic core[J]. J Photoch Photobio A:Chem, 2002, 148:303
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[26]Fu W, Yang H, Li M, et al. Anatase TiO2nanolayer coating on cobalt ferrite nanoparticles for nagnetic photocatalyst[J]. Mater.Lett. 2005, 59:3530
[27]Fu W, Yang H, Chang L, et al. Anatase TiO2nanolayer coating on strontium ferrite nanoparticles for magnetic photocatalyst[J]. Colloid Surfaces A, 2006, 289:47
[28]Fu W, Yang H, Li M, et al. Preparation and photocatalytic characteristics of core-shell structure TiO2/BaFe12O19nanoparticles[J].Mater. Lett., 2006, 60:2723
[29]Chung Y S, Park S B, Kang D W. Magnetically separable titaniacoalted nickel ferrite photocatalyst[J]. Mater. Chem. Phy. 2004,86:375
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[31]Abramson S, Srithammavanh L, Siaugue J-M, et al. Nanometric core-shell-shellγ-Fe2O3/SiO2/TiO2particle[J]. J. Nanopart. Res.2009, 11:459
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[33]Zhang Q, Meng G, Wu J, et al. Study on enhanced photocatalytic activity of magnetically recoverable Fe3O4@C@TiO2nanocomposites with core-shell nanostructure[J]. Opt. Mater. 2015, 46:52
[34]Cong R M, Luo Y J, Yu H Q. Effect of polymer templates on the preparation and photocatalytic activity of CdS quantum dots[J].Acta Chimica Sinica, 2010, 68:1971(丛日敏,罗运军,于怀清.高分子模板对CdS量子点制备及其光催化性能的影响[J].化学学报, 2010, 68(19):1971)
[35]Stefan M, Pana O, Leostean C, et al. Synthesis and characterization of Fe3O4-TiO2core-shell nanoparticles[J]. J. Appl. Phy. 2014,116:114312
[36]Kwiatkowski M, Chassagnon R, Heintz O, et al. Improvement of photocatalytic and photoelectrochemical activity of ZnO/TiO2core/shell system through additional calcination:Insight into the mechanism[J]. Appl. Catal. B-Environ., 2017, 204:200
[37]Ramirez-Ortega D, Melendez A M, Acevedo-Pena P, et al. Semiconducting properties of ZnO/TiO2composites by electrochemical measurements and their relationship with photocatalytic activity[J].Electrochim. Acta, 2014, 140:541
[38]Zheng X, Li D, Li X, et al. Construction of ZnO/TiO2photonic crystal heterostructures for enhanced photocatalytic properties[J].Appl. Catal., B 2015, 168:408
[39]Ramos P G, Flores E, Sanchez L A, et al. Enhanced photoelectrochemical performance and photocatalytic activity of ZnO/TiO2nanostructures fabricated by an electrostatically modified electrospinning[J]. Appl. Surf. Sci., 2017, 426:844
[2]Siuzdak K, Szkoda M, Sawczak M, et al. Novel nitrogen precursors for electrochemically driven doping of titania nanotubes exhibiting enhanced photoactivity[J]. New J. Chem. 2015, 39:2741
[3]Chen Y, Wang L, Wang W, Cao M. Synthesis of Se-doped ZnO nanoplates with enhanced photoelectrochemical and photocatalytic properties[J]. Mater. Chem. Phys. 2017, 199:416
[4]Gombac V, De-Rogatis L, Gasparotto A, et al. TiO2nanopowders dopedwith boron and nitrogen for photocatalytic applications[J].Chem. Phys. 2007, 339:111
[5]Bumajdad A, Madkour M. Understanding the superior photocatalytic activityof noble metals modified titania under UV and visible light irradiation[J]. Phys.Chem. Chem. Phys. 2014, 16:7146
[6]Zhang P, Shao C, Li X, et al. In situ assembly of well-dispersed Au nanoparticles on TiO2/ZnO nanofibers:a three-waysynergistic heterostructure with enhanced photocatalytic activity[J]. J. Hazard.Mater. 2012, 237:331
[7]Li L, Zhang X, Zhang W, et al. Microwave-assistedsynthesis of nanocomposite Ag/ZnO-TiO2and photocatalytic degradation Rhodamine B with different modes[J]. Colloid Surf. A. 2014, 457:134
[8]Zeng H, Liu P, Cai W, et al. Controllable Pt/ZnO porous nanocages with improved photocatalytic activity[J]. J. Phys. Chem. C, 2008,112:19620
[9]Gao X P, Guo Z L, Zhou Y N, et al. Catalytic Performance and characterization of anatase TiO2supported Pd catalysts for the selective hydrogenation of acetylene[J]. Acta Phys.-Chim. Sin. 2017, 33(3):602(高晓平,郭章龙,周亚男,敬方梨,储伟.锐钛矿型TiO2担载的Pd催化剂用于乙炔选择加氢的催化性能及其表征[J].物理化学学报, 2017, 33(3):602)
[10]Volokh M, Diab M, Magen O, et al. Coating and enhanced photocurrent of vertically aligned zinc oxide nanowire arrays with metal sulfide materials[J]. ACS Appl. Mater.Interfaces. 2014, 6:13594
[11]Luo J, Ma L, He T, et al. TiO2/(CdS, CdSe, CdSeS)nanorod heterostructures and photoelectrochemical properties[J]. J. Phys.Chem.C 2012, 16:11956
[12]Zhang C, Wu Z J, Liu J J, et al. Preparation of MoS2/TiO2composite catalyst and its photocatalytic hydrogen production activity under UV irradiation[J]. Acta Phys.-Chim. Sin. 2017, 33(7):1492(张驰,吴志娇,刘建军等. MoS2/TiO2复合催化剂的制备及其在紫外光下的光催化制氢活性[J].物理化学学报, 2017, 33(7):1492)
[13]Marschall R. Semiconductor composites:strategies for enhancing chargecarrier separation to improve photocatalytic activity[J].Adv. Funct. Mater. 2014, 24:2421
[14]Miller D R, Akbar S A, Morris P A. Nanoscale metal oxide-basedheterojunctions for gas sensing:a review[J]. Sensor. Actuator. B.2014, 204:250
[15]Chen Y, Wang L, Wang W, Cao M. Enhanced photoelectrochemical properties of ZnO/ZnSe/CdSe/Cu2-xSe core-shell nanowire arrays fabricated by ion-replacement method[J]. Appl. Catal. B-Environ. 2017, 209:110
[16]Xiao F X. Construction of highly ordered ZnO-TiO2nanotube arrays(ZnO/TNTs)heterostructure for photocatalytic application[J].ACS Appl. Mater.Interfaces, 2012, 4:7055
[17]Shaheen B S, Salem H G, El-Sayed M A, et al. Thermal/electrochemical growth and characterization of one-dimensional ZnO/TiO2hybrid nanoelectrodes for solar fuel production[J]. J. Phys.Chem. C, 2013, 117:18502
[18]Park J Y, Choi S W, Lee J W, et al. Synthesis and gas sensingproperties of TiO2-ZnO core-shell nanofibers[J]. J. Am. Ceram. Soc.2009, 92:2551
[19]Chang J, Kuga Y, Mora-Sero Y, et al. High reduction of interfacial charge recombination in colloidalquantum dot solar cells by metal oxide surface passivation[J]. Nanoscale, 2015, 7:5446
[20]Shao D, Sun H, Xin G, et al. High quality ZnO-TiO2core-shell nanowires for efficient ultraviolet sensing[J]. Appl. Surf. Sci.2014, 314:872
[21]Pan K, Dong Y, Zhou W, et al. Facilefabrication of hierarchical TiO2nanobelt/ZnO nanorod heterogeneous nanostructure:an efficient photoanode for water splitting[J]. ACS Appl. Mater.Interfaces, 2013, 5:8314
[22]Wang L, Liu S, Wang Z, et al. Piezotronic effect enhanced photocatalysis in strained anisotropic ZnO/TiO2nanoplatelets viathermal stress[J]. ACS Nano. 2016, 10:2636
[23]Kwiatkowski M, Bezverkhyy I, Skompska M. ZnO nanorods covered with aTiO2layer:simple sol-gel preparation, and optical, photocatalytic andphotoelectrochemical properties[J]. J. Mater. Chem A. 2015, 3:12748
[24]Watson S, Beydoun D, Amal R S. Synthesis of a novel magnetic photocatalyst by direct deposition of nanosized TiO2crystals onto a magnetic core[J]. J Photoch Photobio A:Chem, 2002, 148:303
[25]Gao Y, Chen B, Li H, et al. Preparation and characterization of a magnetically separated photocatalyst and its catalytic properties[J]. Mater Chem Phys, 2003, 80:348
[26]Fu W, Yang H, Li M, et al. Anatase TiO2nanolayer coating on cobalt ferrite nanoparticles for nagnetic photocatalyst[J]. Mater.Lett. 2005, 59:3530
[27]Fu W, Yang H, Chang L, et al. Anatase TiO2nanolayer coating on strontium ferrite nanoparticles for magnetic photocatalyst[J]. Colloid Surfaces A, 2006, 289:47
[28]Fu W, Yang H, Li M, et al. Preparation and photocatalytic characteristics of core-shell structure TiO2/BaFe12O19nanoparticles[J].Mater. Lett., 2006, 60:2723
[29]Chung Y S, Park S B, Kang D W. Magnetically separable titaniacoalted nickel ferrite photocatalyst[J]. Mater. Chem. Phy. 2004,86:375
[30]Ambashta R D, Sillanpaa M. Water purification using magnetic assistance:a review[J]. J. Hazard. Mater., 2010, 180:38
[31]Abramson S, Srithammavanh L, Siaugue J-M, et al. Nanometric core-shell-shellγ-Fe2O3/SiO2/TiO2particle[J]. J. Nanopart. Res.2009, 11:459
[32]Song X F, Gao L. Fabrication of bifunctional titania/silica-coated magnetic spheres and their photocatalytic activities[J]. J. Am. Ceram. Soc., 2007, 90:4015
[33]Zhang Q, Meng G, Wu J, et al. Study on enhanced photocatalytic activity of magnetically recoverable Fe3O4@C@TiO2nanocomposites with core-shell nanostructure[J]. Opt. Mater. 2015, 46:52
[34]Cong R M, Luo Y J, Yu H Q. Effect of polymer templates on the preparation and photocatalytic activity of CdS quantum dots[J].Acta Chimica Sinica, 2010, 68:1971(丛日敏,罗运军,于怀清.高分子模板对CdS量子点制备及其光催化性能的影响[J].化学学报, 2010, 68(19):1971)
[35]Stefan M, Pana O, Leostean C, et al. Synthesis and characterization of Fe3O4-TiO2core-shell nanoparticles[J]. J. Appl. Phy. 2014,116:114312
[36]Kwiatkowski M, Chassagnon R, Heintz O, et al. Improvement of photocatalytic and photoelectrochemical activity of ZnO/TiO2core/shell system through additional calcination:Insight into the mechanism[J]. Appl. Catal. B-Environ., 2017, 204:200
[37]Ramirez-Ortega D, Melendez A M, Acevedo-Pena P, et al. Semiconducting properties of ZnO/TiO2composites by electrochemical measurements and their relationship with photocatalytic activity[J].Electrochim. Acta, 2014, 140:541
[38]Zheng X, Li D, Li X, et al. Construction of ZnO/TiO2photonic crystal heterostructures for enhanced photocatalytic properties[J].Appl. Catal., B 2015, 168:408
[39]Ramos P G, Flores E, Sanchez L A, et al. Enhanced photoelectrochemical performance and photocatalytic activity of ZnO/TiO2nanostructures fabricated by an electrostatically modified electrospinning[J]. Appl. Surf. Sci., 2017, 426:844