水热法原位合成磁性BiFeO_3-石墨烯杂化材料及其光催化性能
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摘要
采用水热法在石墨烯表面原位合成了石墨烯含量不同的铁酸铋/石墨烯(BiFeO_3-石墨烯)杂化材料。采用X光射线衍射(XRD)、扫描电子显微镜(SEM)、傅里叶红外光谱(FTIR)等研究杂化材料的结构,紫外漫反射光谱(DRS)和荧光光谱(PL spectra)分析其光反应性。在卤钨灯光照条件下测试杂化材料催化降解亚甲基蓝(MB)和罗丹明B(RhB)染料的性能。结果表明,通过水热原位合成法,石墨烯均匀地穿插在BiFeO_3颗粒中并形成大小均一的球状结构。BiFeO_3-石墨烯杂化材料在可见光范围(400~800 nm)的吸收强度明显增加,禁带能隙明显降低。BiFeO_3-石墨烯杂化材料光催化降解有机污染物的速度较纯BiFeO_3显著提高,其中石墨烯质量含量为3%的杂化材料具有最高的降解速度,其光催化降解MB和RhB的速率常数为0.083和0.10,均为纯BiFeO_3降解染料速率的10倍以上,原因在于石墨烯有效地抑制并延后了激发电子和空穴的再结合。由于BiFeO_3具有铁磁性,BiFeO_3-石墨烯杂化材料可以用磁铁回收循环使用,且材料5次循环使用后染料降解效率仍可达到近100%。
The graphene-bismuth ferrite( Graphene-BiFeO_3) hybrids with different graphene contents were synthesized by a hydrothermal method. Their structure was characterized by XRD,SEM and FTIR. Their light reflection and absorption were investigated by UV-visible diffuse reflectance spectroscopy and photoluminescence spectroscopy,respectively. Their photocatalytic properties were evaluated by degrading methylene blue( MB) and rhodamine B(RhB) dyes under irradiation with tungsten light. Results showed that the hybrids had a sphere-like morphology,within which the graphene was uniformly dispersed between the BiFeO_3 spheres. The hybrids had lower band gaps and higher absorption intensities in the visible light region( 400-800 nm) than pure BiFeO_3,and achieved much higher degradation rates for both MB and RhB. The hybrid with a graphene content of 3. 0 wt% exhibited the best photocatalytic performance,and its degradation rate constants for MB and RhB reached to 0. 083 and 0. 10,respectively,which are about 10 times higher than pure BiFeO_3. The introduction of the graphene effectively inhibited the recombination rate of the excited electrons and the holes in BiFeO_3. Their magnetism made them easy to recover from the dye solutions and their photocatalytic activities remained unchanged after recycling 5 times.
The graphene-bismuth ferrite( Graphene-BiFeO_3) hybrids with different graphene contents were synthesized by a hydrothermal method. Their structure was characterized by XRD,SEM and FTIR. Their light reflection and absorption were investigated by UV-visible diffuse reflectance spectroscopy and photoluminescence spectroscopy,respectively. Their photocatalytic properties were evaluated by degrading methylene blue( MB) and rhodamine B(RhB) dyes under irradiation with tungsten light. Results showed that the hybrids had a sphere-like morphology,within which the graphene was uniformly dispersed between the BiFeO_3 spheres. The hybrids had lower band gaps and higher absorption intensities in the visible light region( 400-800 nm) than pure BiFeO_3,and achieved much higher degradation rates for both MB and RhB. The hybrid with a graphene content of 3. 0 wt% exhibited the best photocatalytic performance,and its degradation rate constants for MB and RhB reached to 0. 083 and 0. 10,respectively,which are about 10 times higher than pure BiFeO_3. The introduction of the graphene effectively inhibited the recombination rate of the excited electrons and the holes in BiFeO_3. Their magnetism made them easy to recover from the dye solutions and their photocatalytic activities remained unchanged after recycling 5 times.
引文
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[28]Sun A,Chen H,Song C,et al.Magnetic Bi Fe O3-graphene catalyst and its high visible-light photocatalytic performance[J].RSC Adv,2013,3(13):4332-4340.
[29]Ao Y,Xu L,Wang P,et al.Graphene and Ti O2co-modified flow er-like Bi2O2CO3:A novel multi-heterojunction photocatalyst w ith enhanced photocatalytic activity[J].Appl Surf Sci,2015,355:411-418.
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[31]Ao Y,Tang H,Wang P,et al.Synthesis,characterization and photocatalytic activity of Bi OBr-AC composite photocatalyst[J].Compos Part B-Eng,2014,59(0):96-100.
[32]Luo L,Yang Y,Zhang A,et al.Hydrothermal synthesis of fluorinated anatase Ti O2/reduced graphene oxide nanocomposites and their photocatalytic degradation of bisphenol A[J].Appl Surf Sci,2015,353:469-479.
[33]Saranya M,Ramachandran R,Kollu P,et al.A template-free facile approach for the synthesis of Cu S-r GO nanocomposites tow ards enhanced photocatalytic reduction of organic contaminants and textile effluents[J].RSC Adv,2015,5(21):15831-15840.
[2]Anjusree GS,Nair AS,Nair SV,et al.One-pot hydrothermal synthesis of Ti O2/graphene nanocomposites for enhanced visible light photocatalysis and photovoltaics[J].RSC Adv,2013,3(31):12933-12938.
[3]Lai Q,Luo XP,Zhu SF.Titania nanotube-graphene oxide hybrids w ith excellent photocatalytic activities[J].New Carbon M ater,2016,31(2):121-128.
[4]He T,Zhou Z,Xu W,et al.Visible-light photocatalytic activity of semiconductor composites supported by electrospun fiber[J].Compos Sci Technol,2010,70(10):1469-1475.
[5]Ko S,Banerjee CK,Sankar J.Photochemical synthesis and photocatalytic activity in simulated solar light of nanosized Ag doped Ti O2nanoparticle composite[J].Compos Part B-Eng,2011,42(3):579-583.
[6]Zhu L,Meng ZD,Cho KY,et al.Synthesis of Cd S/CNT-Ti O2w ith a high photocatalytic activity in photodegradation of methylene blue[J].New Carbon M ater,2012,27(3):166-174.
[7]Qiao X,Huang Y,Cheng H,et al.Surface properties,simultaneous photocatalytic and magnetic activities of Ni2Fe VO6nanoparticles[J].Appl Surf Sci,2015,359:259-265.
[8]Xu LJ,Chu W,Gan L.Environmental application of graphenebased Co Fe2O4as an activator of peroxymonosulfate for the degradation of a plasticizer[J].Chem Eng J,2015,263(0):435-443.
[9]Gan L,Shang SM,Yuen CWM,et al.Hydrothermal synthesis of magnetic Co Fe2O4/graphene nanocomposites w ith improved photocatalytic activity[J].Appl Surf Sci,2015,351:140-147.
[10]Yang YC,Liu Y,Wei JH,et al.Electrospun nanofibers of ptype Bi Fe O3/n-type Ti O2hetero-junctions w ith enhanced visible-light photocatalytic activity[J].RSC Adv,2014,4(60):31941-31947.
[11]Zaki MI,Ramadan W,Katrib A,et al.Surface chemical and photocatalytic consequences of Ca-doping of Bi Fe O3as probed by XPS and H2O2decomposition studies[J].Appl Surf Sci,2014,317:929-934.
[12]Upadhyay RK,Soin N,Roy SS.Role of graphene/metal oxide composites as photocatalysts,adsorbents and disinfectants in w ater treatment:a review[J].RSC Adv,2014,4(8):3823-3851.
[13]Gan L,Shang SM,Yuen CWM,et al.Graphene nanoribbon coated flexible and conductive cotton fabric[J].Compos Sci Technol,2015,117:208-214.
[14]Gan L,Shang SM,Yuen CWM,et al.Covalently functionalized graphene w ith d-glucose and its reinforcement to poly(vinyl alcohol)and poly(methyl methacrylate)[J].RSC Adv,2015,5(21):15954-15961.
[15]Gan L,Shang SM,Jiang SX.Impact of vinyl concentration of a silicone rubber on the properties of the graphene oxide filled silicone rubber composites[J].Compos Part B-Eng,2016,84:294-300.
[16]Gan L,Xu LJ,Shang SM,et al.Visible light induced methylene blue dye degradation photo-catalyzed by WO3/Graphene nanocomposites and the mechanism[J].Ceram Int,2016,42:15235-15241.
[17]Wang X-w,Zhou L,Li F.Zn O disks loaded with reduced graphene oxide for the photodegradation of methylene blue[J].New Carbon M ater,2013,28(6):408-413.
[18]Dai JF,Xian T,Di LJ,et al.Preparation of Bi Fe O3-hraphene nanocomposites and their enhanced photocatalytic activities[J].J Nanomater,2013,642897.
[19]Gan L,Shang SM,Hu EL,et al.Konjac glucomannan/graphene oxide hydrogel w ith enhanced dyes adsorption capability for methyl blue and methyl orange[J].Appl Surf Sci,2015,357,Part A:866-872.
[20]Hengky C,Moya X,Mathur ND,et al.Evidence of high rate visible light photochemical decolourisation of Rhodamine B w ith Bi Fe O3nanoparticles associated w ith Bi Fe O3photocorrosion[J].RSC Adv,2012,2(31):11843-11849.
[21]Li Z,Young RJ,Wilson NR,et al.Effect of the orientation of graphene-based nanoplatelets upon the Young's modulus of nanocomposites[J].Compos Sci Technol,2016,123:125-133.
[22]Tan L,Gan L,Hu J,et al.Functional shape memory composite nanofibers w ith graphene oxide filler[J].Compos Part AAppl S,2015,76 Part A:115-123.
[23]Kuila T,Bose S,Khanra P,et al.Characterization and properties of in situ emulsion polymerized poly(methyl methacrylate)/graphene nanocomposites[J].Compos Part A-Appl S,2011,42(11):1856-1861.
[24]Chauhan S,Kumar M,Chhoker S,et al.Substitution driven structural and magnetic transformation in Ca-doped Bi Fe O3nanoparticles[J].RSC Adv,2016,6(49):43080-43090.
[25]Peng L,Deng H,Tian J,et al.Influence of Co doping on structural,optical and magnetic properties of Bi Fe O3films deposited on quartz substrates by sol-gel method[J].Appl Surf Sci,2013,268:146-150.
[26]Li P,Chen Q,Lin Y,et al.Effects of crystallite structure and interface band alignment on the photocatalytic property of bismuth ferrite/(N-doped)graphene composites[J].J Alloy Compd,2016,672:497-504.
[27]Li ZX,Shen Y,Yang C,et al.Significant enhancement in the visible light photocatalytic properties of Bi Fe O3-graphene nanohybrids[J].J M ater Chem A,2013,1(3):823-829.
[28]Sun A,Chen H,Song C,et al.Magnetic Bi Fe O3-graphene catalyst and its high visible-light photocatalytic performance[J].RSC Adv,2013,3(13):4332-4340.
[29]Ao Y,Xu L,Wang P,et al.Graphene and Ti O2co-modified flow er-like Bi2O2CO3:A novel multi-heterojunction photocatalyst w ith enhanced photocatalytic activity[J].Appl Surf Sci,2015,355:411-418.
[30]An X,Jimmy CY.Graphene-based photocatalytic composites[J].RSC Adv,2011,1(8):1426-1434.
[31]Ao Y,Tang H,Wang P,et al.Synthesis,characterization and photocatalytic activity of Bi OBr-AC composite photocatalyst[J].Compos Part B-Eng,2014,59(0):96-100.
[32]Luo L,Yang Y,Zhang A,et al.Hydrothermal synthesis of fluorinated anatase Ti O2/reduced graphene oxide nanocomposites and their photocatalytic degradation of bisphenol A[J].Appl Surf Sci,2015,353:469-479.
[33]Saranya M,Ramachandran R,Kollu P,et al.A template-free facile approach for the synthesis of Cu S-r GO nanocomposites tow ards enhanced photocatalytic reduction of organic contaminants and textile effluents[J].RSC Adv,2015,5(21):15831-15840.