溶剂热合成多级ZnO微球及其光催化降解苯酚
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摘要
以乙二醇为溶剂,KAc为助剂,采用溶剂热法合成多级ZnO微球。通过改变反应温度来调控ZnO微球形貌,并对合成的ZnO微球进行XRD、SEM、PL和UV-Vis DRS等表征分析。结果表明,合成的ZnO为六方纤锌矿晶体结构,由短纳米棒自组装成多级微球。在紫外-可见光照射下,ZnO表现出优异的光催化降解苯酚活性,180℃合成的ZnO样品光催化活性明显优于其他温度合成的样品。用0.1 g的ZnO降解100 mL浓度为5 mg·L~(-1)的苯酚溶液,光照150 min降解率达94.5%。多级ZnO微球光催化性能的提高可推测为较窄的禁带宽度(3.08 eV)有利于吸收光子,较小的晶粒尺寸(25.38 nm)、粗糙的表面以及中空结构有利于反应液与催化剂表面的充分接触。此外,由捕获实验证实光催化降解苯酚的机理是羟基(·OH)为主要的活性自由基,在苯酚降解过程中起主要作用。
Hierarchical ZnO microspheres were synthesized via solvothermal method using ethylene glycol as solvent and potassium acetate as assistant.The morphology of ZnO microspheres was controlled by changing reaction temperature.As-synthesized ZnO microspheres were characterized by XRD,SEM,PL and UV-Vis DRS.The result showed that the synthesized hierarchical ZnO microspheres were composed of short nanorods with wurtzite crystal structure.Under UV-Vis light irradiation,all ZnO samples exhibited excellent photocatalytic activity of phenol degradation.ZnO synthesized at 180 ℃ displayed best photocatlytic activity.In the case of using 0.1 g the ZnO sample in 100 mL 5 mg·L~(-1) phenol solution,degradation conversion was 94.5% after irradiation for 150 min.The enhanced photocatalytic performance of hierarchical ZnO microspheres can be supposed to narrow band gap(3.08 eV) being beneficial for absorption of photons,small paiticle size(25.38 nm),rough surface and hollow structure in favor of sufficient contact between phenol molecules and surface of the catalyst.In addition,a photocatalytic mechanism is proved by carrying out trapping experiments that ·OH is the main active radical and plays important role in the phenol degradation process.
Hierarchical ZnO microspheres were synthesized via solvothermal method using ethylene glycol as solvent and potassium acetate as assistant.The morphology of ZnO microspheres was controlled by changing reaction temperature.As-synthesized ZnO microspheres were characterized by XRD,SEM,PL and UV-Vis DRS.The result showed that the synthesized hierarchical ZnO microspheres were composed of short nanorods with wurtzite crystal structure.Under UV-Vis light irradiation,all ZnO samples exhibited excellent photocatalytic activity of phenol degradation.ZnO synthesized at 180 ℃ displayed best photocatlytic activity.In the case of using 0.1 g the ZnO sample in 100 mL 5 mg·L~(-1) phenol solution,degradation conversion was 94.5% after irradiation for 150 min.The enhanced photocatalytic performance of hierarchical ZnO microspheres can be supposed to narrow band gap(3.08 eV) being beneficial for absorption of photons,small paiticle size(25.38 nm),rough surface and hollow structure in favor of sufficient contact between phenol molecules and surface of the catalyst.In addition,a photocatalytic mechanism is proved by carrying out trapping experiments that ·OH is the main active radical and plays important role in the phenol degradation process.
引文
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[26]Wang D,Sun Y,Shang Q,et al.Effects of the conjugated structure of Fe-bipyridyl complexes on photoinduced electron transfer in TiO2 photocatalytic systems[J].Journal of Catalysis,2017,356:32-42.
[27]Lu J,Meng Q,Lv H,et al.Synthesis of visible-light-driven BiOBrxI1-x solid solution nanoplates by ultrasound-assisted hydrolysis method with tunable bandgap and superior photocatalytic activity[J].Journal of Alloys and Compounds,2018,732:167-177.
[2]Liu B,Zeng H C.Hollow ZnO microspheres with complex nanobuilding units[J].Chemistry of Materials,2007,19(24):5824-5826.
[3]Lepot N,Van Bael M K,Van den Rul H,et al.Synthesis of ZnO nanorods from aqueous solution[J].Materials Letters,2007,61(13):2624-2627.
[4]Li X Y,Liang P,Wang L,et al.Preparation and characterization of high uniformity zinc oxide nanosheets[J].Frontiers of Optoelectronics,2014,7(4):509-512.
[5]Bie X F,Wang C Z,Ehrenberg H,et al.Room-temperature ferromagnetism in pure ZnO nanoflowers[J].Solid State Sciences,2010,12(8):1364-1367.
[6]Wang Y M,Li J H,Hong R Y.Large scale synthesis of ZnO nanoparticles via homogeneous precipitation[J].Jurnal of Central South University of Technology,2012,19(4):863-868.
[7]Liu B,Zeng H C.Hydrothermal synthesis of ZnO nanorods in the diameter regime of 50 nm[J].Journal of the American Chemical Society,2003,125(15):4430-4431.
[8]Shi J X,Liu Y X,Peng Q,et al.ZnO hierarchical aggregates:Solvothermal synthesis and application in dye-sensitized solar cells[J].Nano Research,2013,6(6):441-448.
[9]Wu H Q,Wei X W,Shao M W,et al.Synthesis of zinc oxide nanorods using carbon nanotubes as templates[J].Journal of Crystal Growth,2004,265(1):184-189.
[10]Hasnidawani J N,Azlina H N,Norita H,et al.Synthesis of ZnO nanostructures using sol-gel method[J].Procedia Chemistry,2016,19:211-216.
[11]Xiao S S,Liu L,Lian J S.Solvothermal synthesis of nanocrystalline ZnO with excellent photocatalytic performance[J].Journal of Materials Science:Materials in Electronics,2014,25(12):5518-5523.
[12]Yin Y T,Wu S H,Chen C H,et al.Fabrication of ZnO nanorods in one pot via solvothermal method[J].Journal of the Chinese Chemical Society,2011,58(6):749-755.
[13]Becker J,Raghupathi K R,Zhao D,et al.Tuning of the crystallite and particle sizes of ZnO nanocrystalline materials in solvothermal synthesis and their photocatalytic activity for dye degradation[J].The Journal of Physical Chemistry C,2011,115(28):13844-13850.
[14]褚亚洲,孙亚平,柴梅俊,等.ZnO纳米棒阵列的改进水热方法制备、银修饰及光催化活性研究[J].工业催化,2014,22(12):928-931. Chu Yazhou,Sun Yaping,Cai Meijun,et al.Preparation of ZnO nanorod arrays through modified hydrothermal process,Ag deposition and their photocatalytic activity[J].Industrial Catalysis,2014,22(12):928-931.
[15]Benhebal H,Chaib M,Salmon T,et al.Photocatalytic degradation of phenol and benzoic acid using zinc oxide powders prepared by the sol-gel process[J].Alexandria Engineering Journal,2013,52(3):517-523.
[16]Xie M,Meng Q,Luan P,et al.Synthesis of mesoporous TiO2-coupled Fe2O3 as efficient visible nano-photocatalysts for degrading colorless pollutants[J].RSC Advances,2014,4:52053-52059.
[17]王英连,孙汪典,任思雨,等.ZnO薄膜的制备及光催化性能研究[J].工业催化,2005,13(1):37-41.Wang Yinglian,Sun Wangdian,Ren Siyu,et al.Preparation and photocatalytic properties of zinc oxide thin film[J].Industrial Catalysis,2005,13(1):37-41.
[18]Duo S,Zhang L,Zhong R,et al.Controllable tartaric acid modified ZnO crystals and their modification-determinedoptical, superhydrophilic/hydrophilic and photocatalytic properties[J].Journal of Alloys and Compounds,2018,768:214-229.
[19]Yan W,Jiang W,Zhang Q,et al.Structure and magnetic properties of nickel-zinc ferrite microspheres synthesized by solvothermal method[J].Materials Science and Engineering B,2010,171:144-148.
[20]Shen G Z,Bando Y,Lee C J,et al.Synthesis and evolution of novel hollow ZnO urchins by a simple thermal evaporation process[J].The Journal of Physical Chemistry B,2005,109(21):10578-10583.
[21]Zeng H B,Duan G T,Li Y,et al.Blue luminescence of ZnO nanoparticles based on non-equilibrium processes:defect origins and emission controls[J].Advanced Functional Materials,2010,20(4),561-572.
[22]Lin B X,Fu Z X.Green luminescent center in undoped zinc oxide films deposited on silicon substrates[J].Applied Physics Letters,2001,79(7):943-945.
[23]Yuan Z L,Fu M X,Ren Y J,et al.Synthesis of zinc oxide colloidal nanorods for inorganic-organic hybrid photodiode application[J].Journal of Materials Science:Materials in Electronics,2015,26(10):8212-8216.
[24]Wang J P,Wang Z Y,Huang B B,et al.Oxygen vacancy induced band-gap narrowing and enhanced visible light photocatalytic activity of ZnO[J].ACS Applied Materials &Interfaces,2012,4(8):4024-4030.
[25]Pardeshi S K,Patil A B.A simple route for photocatalytic degradation of phenol in aqueous zinc oxide suspension using solar energy[J].Solar Energy,2008,82(8):700-705.
[26]Wang D,Sun Y,Shang Q,et al.Effects of the conjugated structure of Fe-bipyridyl complexes on photoinduced electron transfer in TiO2 photocatalytic systems[J].Journal of Catalysis,2017,356:32-42.
[27]Lu J,Meng Q,Lv H,et al.Synthesis of visible-light-driven BiOBrxI1-x solid solution nanoplates by ultrasound-assisted hydrolysis method with tunable bandgap and superior photocatalytic activity[J].Journal of Alloys and Compounds,2018,732:167-177.