微波辅助的多元醇法合成CoNi纳米材料_英文_
ceo2 纳米粒子的合成
ceo2 纳米粒子的合成英文回答：Synthesis of CEO2 Nanoparticles.Cerium oxide nanoparticles (CEO2) are versatile materials with a wide range of applications, including in catalysis, sensors, and biomedicine. Their unique properties, such as their high oxygen storage capacity, redox activity, and low toxicity, make them particularly attractive for various applications.There are several methods for synthesizing CEO2 nanoparticles, including chemical precipitation, sol-gel, hydrothermal, and combustion synthesis. Each method has its own advantages and disadvantages, and the choice of method depends on the desired properties of the nanoparticles.Chemical Precipitation.Chemical precipitation is a simple and cost-effective method for synthesizing CEO2 nanoparticles. In this method, a cerium salt, such as cerium nitrate or cerium chloride,is dissolved in water and then precipitated by adding a base, such as sodium hydroxide or ammonium hydroxide. The precipitate is then washed and dried to obtain the CEO2 nanoparticles.The chemical precipitation method is versatile and allows for the control of the size, shape, andcrystallinity of the nanoparticles. However, this methodcan be sensitive to the reaction conditions, and it can be difficult to obtain nanoparticles with uniform properties.Sol-Gel.The sol-gel method involves the hydrolysis and condensation of a cerium precursor, such as cerium alkoxide, in a solvent. The resulting sol-gel is then heated to form the CEO2 nanoparticles.The sol-gel method offers good control over the sizeand shape of the nanoparticles. However, this method can be time-consuming and can require specialized equipment.Hydrothermal.Hydrothermal synthesis is a method for synthesizing CEO2 nanoparticles in a closed vessel under high temperature and pressure. In this method, a cerium precursor is dissolved in water and then heated in a sealed vessel. The high temperature and pressure promote the formation of CEO2 nanoparticles.The hydrothermal method is a versatile method that allows for the control of the size, shape, andcrystallinity of the nanoparticles. However, this method can be expensive and can require specialized equipment.Combustion Synthesis.Combustion synthesis is a method for synthesizing CEO2 nanoparticles by rapidly heating a mixture of ceriumnitrate and a fuel, such as glycine or urea. The rapidheating causes the fuel to combust, which provides the energy for the formation of CEO2 nanoparticles.Combustion synthesis is a simple and cost-effective method. However, this method can be difficult to control, and it can be difficult to obtain nanoparticles withuniform properties.中文回答：CEO2 纳米粒子的合成。
微波辅助离子液体合成球形纳米团簇2010年1月
/Langmuir©2010American Chemical SocietyIonic Liquid-Based Route to Spherical NaYF4Nanoclusters with the Assistance of Microwave Radiation and Their Multicolor UpconversionLuminescenceCheng Chen,†,‡Ling-Dong Sun,†Zhen-Xing Li,†Le-Le Li,†Jun Zhang,*,‡Ya-Wen Zhang,†and Chun-Hua Yan*,††Beijing National Laboratory for Molecular Sciences,State Key Lab of Rare Earth Materials Chemistry and Applications,PKU-HKU Joint Lab in Rare Earth Materials and Bioinorganic Chemistry,Peking University, Beijing100871,P.R.China,and‡College of Chemistry and Chemical Engineering,Inner Mongolia University,Hohhot010021,P.R.ChinaReceived December2,2009.Revised Manuscript Received January3,2010An ionic liquid(IL)(1-butyl-3-methylimidazolium tetrafluoroborate)-based route was introduced into the synthesis of novel spherical NaYF4nanoclusters with the assistance of a microwave-accelerated reaction system.X-ray diffraction (XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),high-resolution TEM (HRTEM),selected area electron diffraction(SAED),energy-dispersive X-ray spectroscopy(EDS)and upconversion (UC)luminescence spectroscopy were used to characterize the obtained products.Interestingly,these spherical NaYF4 nanoclusters with diameters ranging from200to430nm are formed by the self-assembly of small nanoparticles.The diameters of the nanoclusters could be easily tuned just by changing the amounts of the precursors.By conducting the control experiments with different ILs or precursors,it is proven that the ILs have played key roles,such as the solvents for the reaction,the absorbents of microwave irradiation,and the major fluorine sources for the formation of the NaYF4 nanocrystals.The UC luminescence properties of the Ln3þcodoped NaYF4were measured,and the results indicate that the nanoclusters obtained in BmimBF4exhibit excellent UC properties.Since this IL-based and microwave-accelerated procedure is efficient and environmentally benign,we believe that this method may have some potential applications in the synthesis of other nanomaterials.1.IntroductionIonic liquids(ILs)have recently attracted much attention since they have a variety of potential applications in organic synthesis, electrochemistry,catalysis,chemical separation,and so on.1ILs can be used as green solvents to replace conventional organic solvents in many chemical processes because of their unique properties,such as their negligible vapor pressure,good thermal and chemical stability,extremely high ionic conductivity,wide electrochemical windows,and so on.2,3In recent years,ILs have emerged as one of the most promising categories of medium for the fabrication of nanomaterials with various morphologies,since ILs possess tunable properties so that they can easily interact with various surfaces and chemical reaction environments.4-6 Smarsly et al.designed a low-temperature route to synthesize rutile nanorods just by the stabilization of an amorphous phase,which then converted to rutile by a simple extraction of the stabilizer (IL).7Chen et al.demonstrated a novel route for the prepara-tion of IL-stabilized ZnO nanocrystals with remarkably high photoluminescence quantum yields.8Moreover,because of their high polarity,ILs are also considered to be excellent microwave absorbents.9Microwave dielectric heating has aroused many interests in recent years because there are many advantages compared to conventional heating for chemical reactions,such as higher heating rate,uniform heating without thermal gradients, selective heating properties,and higher yields in shorter reaction time.10,11Because of these special properties,microwave irradia-tion is becoming an important pathway for the preparation of nanomaterials.It not only benefits the spontaneous nucleation of inorganic materials,12-14but also enables reactions to be per-formed at higher temperatures,which results from the super-heating phenomenon of the solvents caused by the microwave dielectric heating.15,16The exploration of the combination be-tween ILs and microwave radiation has just begun,which would facilitate the fabrication of novel nanomaterials with designed structures and functions.17-19*Corresponding author.Fax:þ86-10-6275-4179;e-mail:yan@(C.-H.Y.).Fax:þ86-471-499-2278;e-mail:cejzhang@(J.Z.).(1)Parvulescu,V.I.;Hardacre,C.Chem.Rev.2007,107,2615.(2)Antonietti,M.;Kuang,D.B.;Smarsly,B.;Zhou,Y.Angew.Chem.,Int.Ed. 2004,43,4988.(3)Gao,H.X.;Li,J.C.;Han,B.X.;Chen,W.N.;Zhang,J.L.;Zhang,R.;Yan,D.D.Phys.Chem.Chem.Phys.2004,6,2914.(4)Lodge,T.P.Science2008,321,50.(5)Kim,T.Y.;Kim,W.J.;Hong,S.H.;Kim,J.E.;Suh,K.S.Angew.Chem., Int.Ed.2009,48,3806.(6)Zhou,Y.;Antonietti,M.Adv.Mater.2003,15,1452.(7)Kaper,H.;Endres,F.;Djerdj,I.;Antonietti,M.;Smarsly,B.M.;Maier,J.; Hu,Y.S.Small2007,3,1753.(8)Liu,D.P.;Li,G.D.;Su,Y.;Chen,J.S.Angew.Chem.,Int.Ed.2006,45, 7370.(9)Ding,K.L.;Miao,Z.J.;Liu,Z.M.;Zhang,Z.F.;Han,B.X.;An,G.M.; Miao,S.D.;Xie,Y.J.Am.Chem.Soc.2007,129,6362.(10)Gabriel,C.;Gabriel,S.;Grant,E.H.;Halstead,B.S.J.;Mingos,D.M.P. Chem.Soc.Rev.1998,27,213.(11)Hu,X.L.;Yu,J.C.Adv.Funct.Mater.2008,18,880.(12)Gerbec,J.A.;Magana,D.;Washington,A.;Strouse,G.F.J.Am.Chem. Soc.2005,127,15791.(13)Kim,S.H.;Lee,S.Y.;Yi,G.R.;Pine,D.J.;Yang,S.M.J.Am.Chem.Soc. 2006,128,10897.(14)Hu,X.L.;Gong,J.M.;Zhang,L.Z.;Yu,J.C.Adv.Mater.2008,20,4845.(15)Baghurst,D.R.;Mingos,mun.1992,9, 674.(16)Saillard,R.;Poux,M.;Berlan,J.Tetrahedron1995,51,4033.(17)Yang,L.X.;Zhu,Y.J.;Wang,W.W.;Tong,H.;Ruan,M.L.J.Phys. Chem.B2006,110,6609.(18)Buhler,G.;Feldmann,C.Angew.Chem.,Int.Ed.2006,45,4864.(19)Lovingood,D.D.;Strouse,G.F.Nano.Lett.2008,8,3394.Article Chen et al.Recent decades have witnessed an explosion in research devoted to preparing upconversion(UC)nanocrystals because of their potential applications in solid-state lasers,optical sto-rage,flat-panel displays,optical fiber-based telecommunica-tions,low-intensity IR imaging,and so on.20,21As an impor-tant category of rare earth fluoride compounds,AREF4(A= alkali;RE=rare earth)is regarded as an excellent host matrix for UC phosphors.22,23Great efforts have been devoted to the synthesis of shape-controllable NaYF4nanocrystals via different routes and the study of their optical properties.24-26Zhao et al. reported the synthesis of NaYF4nanotubes via an in situ ion exchange procedure from the corresponding hydroxides.27van Veggel’s group developed an efficient route to prepare a UC nanoparticle-polymer composite.28A core/shell structure of NaYF4/silica was prepared by Zhang’s group,and multi-color UC fluorescence properties of the nanoparticles were measured.29,30Recently,IL was also applied to synthesize hexagonal-phase NaYF4UC nanophosphors through an ionothermal method.31However,the unique properties of ILs, such as their high polarity and the resulting excellent microwave absorbing ability,have not been reflected and emphasized. Additionally,the effects of different ILs on the formation process of the final nanostructures have not been investigated.In this work,we have introduced a microwave-accelerated reaction system into the synthesis of novel spherical NaYF4 nanoclusters in1-butyl-3-methylimidazolium tetrafluoroborate (BmimBF4),with which the reactions could be completed in a significantly short time and highly crystallized products could be obtained.Interestingly,these NaYF4nanoclusters are formed by the self-assembly of small nanoparticles and exhibit excellent UC luminescent property.By conducting control experiments,it is proven that ILs play key roles in the formation of the final nanostructure,since they act not only as the solvents and micro-wave absorbents in the synthetic process,but also as the major fluorine sources for the preparation of NaYF4nanocrystals.2.Experimental Section2.1.Materials.Trifluoroacetic acid(99%,Acros),Na-(CF3COO)(>97%,Acros),Na(CH3COO)(99.0%,Beijing Che-mical Plant),1-butyl-3-methylimidazolium tetrafluoroborate (BmimBF4,99%,Alpha),1-butyl-3-methylimidazolium hexa-fluorophosphate(BmimPF6,98%,Alpha),and1-butyl-3-methyl-imidazolium bromide(BmimBr,99%,Alpha)were used as received.RE(CF3COO)3(RE=Y,Yb,Er,Tm)and Y(CH3COO)3 were prepared from the corresponding lanthanide oxides follow-ing the literature method.322.2.Synthesis of NaYF4with Trifluoroacetate Salts in BmimBF4.For a typical synthesis,0.5mmol Na(CF3COO)and0.5mmol Y(CF3COO)3were taken as the precursors and added into5mL IL(BmimBF4)followed by vigorously magnetic stirring at room temperature for2h to obtain a transparent solution,which was then heated to200°C by microwave irradiation and maintained for5min.The temperature ramping process was accomplished by two steps(20°C/min from room temperature to100°C and then10°C/min from100to200°C)in a CEM microwave-accelerated system at400W.After the microwave reaction was completed,the temperature of the system was reduced to room temperature.Then after washing and centrifugation several times,white precipitates were collected and dried at65°C.2.3.Synthesis of NaYF4with Acetate Salts in BmimBF4. The synthetic procedure was the same as that used to synthesize cubic NaYF4in BmimBF4,except that0.5mmol Na(CH3COO) and0.5mmol Y(CH3COO)3were taken as the precursors instead of the trifluoroacetate salts.2.4.Reaction of Trifluoroacetate Salts in BmimBr.The synthetic procedure was the same as that used to synthesize cubic NaYF4by the reaction of Na(CF3COO)and Y(CF3COO)3, except that BmimBr was used as the solvent instead of BmimBF4.2.5.Synthesis of NaYF4with Trifluoroacetate Salts in BmimPF6.The synthetic procedure was the same as that used to synthesize cubic NaYF4by the reaction of Na(CF3COO)and Y(CF3COO)3,except that BmimPF6was used as the solvent instead of BmimBF4.2.6.Synthesis of NaYF4:Yb,Er and NaYF4:Yb,Tm with Trifluoroacetate Salts in BmimBF4.The synthetic procedure was the same as that used to synthesize cubic NaYF4in BmimBF4, except that0.5mmol Na(CF3COO)and stoichiometric amounts of Y(CF3COO)3,Yb(CF3COO)3,Er(CF3COO)3/Tm(CF3COO)3 were taken as the precursors.2.7.Synthesis of NaYF4:Yb,Er and NaYF4:Yb,Tm with Trifluoroacetate Salts in BmimPF6.The synthetic procedure was the same as that used to synthesize cubic NaYF4in BmimPF6, except that0.5mmol Na(CF3COO)and stoichiometric amounts of Y(CF3COO)3,Yb(CF3COO)3,Er(CF3COO)3/Tm(CF3COO)3 were taken as the precursors.2.8.Characterization.Powder X-ray diffraction(XRD) patterns of the dried powders were recorded on a Rigaku D/ MAX-2000diffractometer(Japan)with Cu K R radiation(λ= 1.5406A).Scanning electron microscopy(SEM)observations were carried out with DB-235focused ion beam(FIB)system operated at an acceleration voltage of15kV.Transmission electronic microscopy(TEM),and selected area electron diffrac-tion(SAED)were performed with a JEOL-2100transmission electron microscope(Japan)operated at200kV.High-resolution TEM(HRTEM)characterization and energy-dispersive X-ray spectroscopy(EDS)were taken on a JEOL-2100F transmission electron microscope(Japan)equipped with an EDS detector.The UC luminescence spectra were recorded on a Hitachi F-4500 fluorescence spectrophotometer equipped with an external tun-able2W980nm laser diode(P max=500mW at1000mA).3.Results and DiscussionThe combination of ILs and microwave dielectric heating could provide us with a facile and green route to fabricate nanomater-ials.The XRD pattern of the product synthesized with trifluor-oacetate salts(Na(CF3COO)and Y(CF3COO)3)in BmimBF4is shown in Figure1a.All the peaks can be well indexed as a cubic phase of NaYF4(JCPDS card No.39-0724).The well-resolved four peaks between20°and60°in2θvalue could be assigned to (111),(200),(220),and(311)planes of cubic NaYF4nanocrystals. The SEM image(Figure2a)indicates that NaYF4nanospheres with diameters ranging from200to430nm could be obtained. The TEM image(Figure2b)shows that these spherical nanoclus-ters have rough surfaces,and they are formed by the self-assembly of small nanoparticles.The inset of Figure2b is the SAED pattern(20)Zhang,F.;Wan,Y.;Yu,T.;Zhang,F.Q.;Shi,Y.F.;Xie,S.H.;Li,Y.G.; Xu,L.;Tu,B.;Zhao,D.Y.Angew.Chem.,Int.Ed.2007,46,7976.(21)Sivakumar,S.;van Veggel,F.C.J.M.;May,P.S.J.Am.Chem.Soc.2007, 129,620.(22)Boyer,J.C.;Cuccia,L.A.;Capobianco,J.A.Nano.Lett.2007,7,847.(23)Li,C.X.;Yang,J.;Yang,P.P.;Zhang,X.M.;Lian,H.Z.;Lin,J.Cryst. Growth Des.2008,8,923.(24)Mai,H.X.;Zhang,Y.W.;Si,R.;Yan,Z.G.;Sun,L.D.;You,L.P.;Yan,C.H.J.Am.Chem.Soc.2007,129,6362.(25)Wang,L.Y.;Li,Y.D.Chem.Mater.2007,19,727.(26)Wang,H.Q.;Nann,T.ACS Nano2009,3,3804.(27)Zhang,F.;Zhao,D.Y.ACS Nano2009,3,159.(28)Boyer,J.C.;Johnson,N.J.J.;van Veggel,F.C.J.M.Chem.Mater.2009, 21,2010.(29)Li,Z.Q.;Zhang,Y.;Jiang,S.Adv.Mater.2008,20,4765.(30)Qian,H.S.;Guo,H.C.;Ho,P.C.L.;Mahendran,R.;Zhang,Y.Small 2009,5,2285.(31)Liu,X.M.;Zhao,J.W.;Sun,Y.J.;Song,K.;Yu,Y.;Du,C.;Kong,X.G.; Zhang,mun.2009,43,6628.(32)Roberts,J.E.J.Am.Chem.Soc.1961,83,1087.Chen et al.Articletaken on a single sphere.The discontinuous rings again reveal that the cluster is formed by the aggregation of many small nanopar-ticles.Observation from the HRTEM image (Figure 2c)reveals that the size of the small nanoparticles in these nanoclusters is about 10to 15nm.Moreover,the nanoparticles are single crystals with an interplanar spacing of 0.31nm corresponding to the (111)facets of cubic NaYF 4,which confirms that the nanoparticles are highly crystallized.Scheme 1illustrates the formation process of the spherical NaYF 4nanoclusters.Since the ILs with high polarity have strong microwave absorbing ability,the whole reaction system could reach a high temperature rapidly under microwave irradiation,which results in spontaneous nucleation.9Followed by the rapid growth of these nuclei,large quantities of NaYF 4nanocrystals are formed within an extremely short time.Therefore,the size of the as-synthesized nanoparticles is very small.Because of their high surface energy,the freshly formed small nanoparticles tend to aggregate rapidly into spherical nanoclusters.14Furthermore,the size of the spherical NaYF 4nanoclusters could be tuned by changing the amounts of the trifluoroacetate precursors.As shown in Table 1,samples 1-3were prepared bychanging the amounts of the trifluoroacetate salts from 0.5to 0.1mmol.It could be observed from the TEM images in Figure 3a,c,e that the size of the NaYF 4nanoclusters decreases with the decrease of the precursors’amounts.By measuring 200nanoclusters for each sample,we could get the size distribu-tions of the nanoclusters (Figure 3b,d,f),and the average sizes of these three samples are 302,163,and 79nm,respectively.This size tunability could be resulted from the differences in crystal nuclei caused by varying additions of the precursors.33Because higher concentration of trifluoroacetate salts could accelerate the decom-position of Na(CF 3COO)and Y(CF 3COO)3,more nuclei would form in the solution,which leads to the formation of larger NaYF 4nanoclusters.The factors governing the formation of the spherical NaYF 4nanoclusters were studied,and it was found that the IL had played key roles in the self-assembly process of the final nano-structure.As is known,the existence of sodium,yttrium,and fluorine sources is indispensable for the formation of NaYF 4nanocrystals.In this method,both the precursors (trifluoroace-tate salts)and the solvent (BmimBF 4)might serve as the supplier of the fluoride ions.In order to investigate where the fluoride ions came from and the role that IL played on the synthetic procedure of NaYF 4,control experiments were carried out by changing the inorganic precursors or the ILs while keeping other synthetic parameters constant.Figure 1c shows the XRD pattern of the sample obtained by the reaction of acetate salts Na(CH 3COO)and Y(CH 3COO)3in BmimBF 4.It can be clearly observed that cubic NaYF 4could also be obtained without the existence of CF 3COO -.This indicates that the IL provided the fluorine source for the formation of NaYF 4by the decomposition of BmimBF 4,which compares well with the reported results that BF 4-ions are prone to thermal decomposition to produce F -at a certain temperature.34,35To further confirm it,another control experi-ment was carried out just by changing the molecular composition of the ILs.The XRD pattern (Figure 1d)shows that NaYF 4couldFigure 1.(a)XRD pattern of NaYF 4synthesized via the reaction of trifluoroacetate precursors in BmimBF 4.(b)XRD pattern of NaYF 4synthesized via the reaction of trifluoroacetate precursors in BmimPF 6.(c)XRD pattern of NaYF 4synthesized via the reaction of acetate precursors in BmimBF 4.(d)XRD pattern of the product synthesized via the reaction of trifluoroacetate pre-cursors inBmimBr.Figure 2.(a)SEM image of the NaYF 4nanoclusters obtained inBmimBF 4.(b)TEM image of two NaYF 4nanoclusters obtained in BmimBF 4and the ED pattern (inset).(c)HRTEM image taken on the edge of a NaYF 4nanocluster.Scheme 1.Schematic Representation of the Formation of NaYF 4Nanocrystals Obtained in DifferentILsTable 1.Average Diameters of the NaYF 4Nanoclusters Obtained via the Reaction of Different Amounts of Trifluoroacetate Precursorsin BmimBF 4sampleNa(CF 3COO)/mmolY(CF 3COO)3/mmolaverage diameters/nm 10.50.530220.250.2516330.10.179(33)Ge,J.P.;Hu,Y.X.;Biasini,M.;Beyermann,W.P.;Yin,Y.D.Angew.Chem.,Int.Ed.2007,46,4342.(34)Fox,D.;Gilman,J.;Long,H.D.;Trulove,P.J.Chem.Thermodyn.2005,37,900.(35)Koval’chuk, E.;Reshetnyak,O.;Kozlovs’ka,Z.;B z a’ejowski,J.;Gladyshevs’kyj,R.;Obushak,M.Thermochim.Acta 2006,444,1.Article Chen et al.not be synthesized under the same condition by the use of trifluoroacetate salts (Na(CF 3COO)and Y(CF 3COO)3)and IL bearing bromide (BmimBr),and no signal of fluorine was detected by EDS for the final product (Figure 4a,b),which also pointed out that CF 3COO -did not decompose during the micro-wave heating process and did not provide the indispensable F -for the preparation of NaYF 4.The results of the above experiments illuminated that BmimBF 4not only served as the solvent and microwave absorbent in the whole synthetic process,but also acted as the building block and the major fluorine source for the formation of NaYF 4nanoclusters.Based on the above analysis,it is reasonable to deduce that NaYF 4nanocrystals may also be synthesized in other ILs bearing fluorine.So we applied the same synthetic procedure to prepare NaYF 4nanocrystals in BmimPF 6.As we expected,the XRD pattern (Figure 1b)shows that cubic NaYF 4could be achieved,but a peak of NaF was observed at 38.4°in 2θvalue.This probably could be explained as follows:The thermal degradation of BmimPF 6is relatively easier than that of BmimBF 4,36because the bond energy of P -F is weaker compared with that of B -F.19Therefore,high concentration of fluoride ions could be presented in the system of BmimPF 6,which might lead to the formation of NaF.The TEM image in Figure 5a illustrates that spherical to ellipsoidal nanoparticles could be obtained in BmimPF 6.The interplanar spacing shown in the HRTEM image (Figure 5b)is about 0.31nm corresponding to the (111)facets of cubic NaYF 4,which confirms that the nanoparticles are single crystals with high crystallinity.By comparison of Figure 2b and Figure 5a,we caneasily see that the morphology of the NaYF 4nanocrystals obtained in BmimPF 6is different from that of the nanoclusters obtained in BmimBF 4.This may be caused by the different viscosities of these two ILs.As is reported by Afonso´s group,the viscosity of BmimPF 6is higher than that of BmimBF 4.37Thus the assembly and aggregation of the small nanoparticles might be prevented to some extent in BmimPF 6,thus affecting the final morphology.In order to elucidate the effect of microwave dielectric heating on the preparation of the NaYF 4nanoclusters,the comparison between the samples synthesized through the ionothermal method and the microwave method was investigated.The XRD pattern (Figure S1in the Supporting Information)indicates that the product of the ionothermal treatment is cubic NaYF 4.TEM images (Figure S2in the Supporting Information)show that the aggregates of NaYF 4nanoparticles could also be obtained.However,the shape of these aggregates is not as regular as the spherical nanoclusters obtained through the microwave method.At the same time,some rectangular structures could also be observed in the same sample.The existence of different structures in the product may have resulted from the thermal gradients in the ionothermal reaction system.The vessel for the ionothermal reaction serves as an intermediary in the whole process,through which the energy could transfer from the oven to the solvent and then to the reactants.This could result in thermal gradients throughout the bulk solution,which lead to the formation of nonuniform reaction conditions.12However,the effect of thermal gradients could be eliminated in the microwave-accelerated system,which leads to the uniform morphology of the NaYF 4nanocrystals.The UC emission can be realized by doping cubic NaYF 4with lanthanide ions.The morphologies of the UC nanocrystals are not affected by doping with Ln 3þ(Figure 6).Figure 7a,b shows the fluorescence spectra for a 1wt %colloidal solution of NaYF 4:20%Yb 3þ,2%Er 3þand NaYF 4:20%Yb 3þ,0.2%Tm 3þin these two different ILs (BmimBF 4and BmimPF 6)under the excitation of a 980nm laser diode.The spectra of NaYF 4:Yb 3þ,Er 3þnanocrystals exhibit two emission bands,which could be attributed to 2H 11/2f 4I 15/2,4S 3/2f 4I 15/2,and 4F 9/2f 4I 15/2transi-tions of Er 3þ.The emission bands of NaYF 4:Yb 3þ,Tm 3þnano-crystals at 450-500nm and 630-670nm could be assigned to the 1G 4f 3H 6and 1G 4f 3F 4transition of Tm 3þ.38Interestingly,the UC emission intensity of nanoclusters obtained in BmimBF 4was enhanced nearly eight times compared with that of the nanopar-ticles in BmimPF 6.It is well-known that the UC intensity may be influenced by the surface state of nanoparticles.As the ratio of the surface defects decreases,the nonradiative decay is reduced,which would cause the increase of the emission intensity.39In our work,the formation of the NaYF 4nanoclusters might result in the surface reduction of the primary nanoparticles,which is caused by the hard connection among the nanoparticles formed during the self-assembling process.Therefore,the nonradiative centers existing on the surface of the nanocrystals will be eliminated partially,which finally enhances the intensity of the NaYF 4nanoclusters.40,41Figure 7c shows the strong UC lumi-nescence photographs for the 1wt %colloidal solution of the NaYF 4:20%Yb 3þ,2%Er 3þand NaYF 4:20%Yb 3þ,0.2%Tm 3þFigure 3.TEM images and corresponding size distributions of samples 1(a,b),2(c,d),and 3(e,f).(36)Huddleston,J.G.;Visser,A.E.;Reichert,W.M.;Willauer,H.D.;Broker,G.A.;Rogers,R.D.Green Chem.2001,3,156.(37)Branco,L.C.;Rosa,J.N.;Ramos,J.J.M.;Afonso,C.A.M.Chem.;Eur.J.2002,8,3671.(38)Wang,F.;Liu,X.G.J.Am.Chem.Soc.2008,130,5642.(39)Vetrone,F.;Naccache,R.;Mahalingam,V.;Morgan,C.G.;Capobianco,J.A.Adv.Funct.Mater.2009,19,2924.(40)Bovero,E.;van Veggel,F.C.J.M.J.Phys.Chem.C 2007,111,4529.(41)Mai,H.X.;Zhang,Y.W.;Sun,L.D.;Yan,C.H.J.Phys.Chem.C 2007,111,13721.Chen et al.Articlenanoclusters in BmimBF 4,implying that these nanoclusters are excellent UC hosts.The emission intensity of UC nanomaterials could be easily tuned just by changing the doping amounts of the lanthanide ions (Figure 8).For the NaYF 4:Yb 3þ,Er 3þnanoclus-ters obtained in BmimBF 4,the UC emission intensity obviously decreases when the concentration of Er 3þincreases from 0.2%to 2%with the Yb 3þconcentration fixed at 20%.For the NaYF 4:Yb 3þ,Tm 3þnanoclusters obtained in BmimBF 4,the UC emis-sion intensity also decreases with the increase of the Tm 3þconcentration from 0.2%to 2%,while keeping the concentration of Yb 3þat 20%.According to these results,it could be concluded that higher concentrations of Er 3þor Tm 3þmay cause concen-tration quenching of the spherical UC nanoclusters.41Further-more,we investigated how the size distribution affected the UC properties of the spherical NaYF 4:Yb 3þ,Er 3þ/Tm 3þnanoclus-ters.As shown in Figure 9,the UC emission intensity of NaYF 4:20%Yb 3þ,2%Er 3þand NaYF 4:20%Yb 3þ,2%Tm 3þde-creased when the average size of the nanoclusters was reducedfrom 302to 79nm.Because of the higher surface area of the smaller nanoclusters,14the nonradiative centers existing on the surface of the nanoparticles increased with the decrease of the size of the nanoclusters.Therefore,the UC emission intensity of the large nanoclusters would be enhanced compared with that of the small nanoclusters.The influence of different thermal treatment methods (microwave irradiation and ionothermal)on the UC prop-erties of the NaYF 4:20%Yb 3þ,2%Er 3þand NaYF 4:20%Yb 3þ,2%Tm 3þnanocrystals was also studied.The results (Figure S3in the Supporting Information)illuminated that the emission intensity of the UC nanocrystals synthe-sized via the microwave dielectric heating was slightly increased compared with that of the nanocrystals synthe-sized via the ionothermal method.The reason isthatFigure 4.(a)TEM image and (b)corresponding EDS spectrum of the product obtained inBmimBr.Figure 5.(a)TEM image,(b)HRTEM image,and (c)size dis-tribution of NaYF 4nanoparticles obtained in BmimPF 6.Figure 6.TEM images of (a)R -NaYF 4:20%Yb 3þ,2%Er 3þand(b)R -NaYF 4:20%Yb 3þ,0.2%Tm 3þnanoclusters obtained in BmimBF 4.TEM images of (c)R -NaYF 4:20%Yb 3þ,2%Er 3þand (d)R -NaYF 4:20%Yb 3þ,0.2%Tm 3þnanoparticles obtained in BmimPF 6.Article Chen et al.relative higher crystallinity and uniformity of the nano-clusters could be achieved through the microwave irradia-tion,which resulted in the increase of the UC emission intensity.26,294.ConclusionIn summary,we have developed a rapid microwave-assisted process to synthesize cubic NaYF 4in fluorine-contained ILs.It shows that small nanoparticles could form spontaneously in BmimBF 4due to the microwave irradiation,and then spherical cubic NaYF 4nanoclusters could be obtained by the self-assembly of these primary nanoparticles.From the control experiments with different precursors or ILs,it can be concluded that ILs play key roles,such as the solvent for the reaction,the absorbent of microwave irradiation,and the source of fluoride ions for the formation of NaYF 4nanocrystals.By the investigation ofdifferent thermal treatment methods,it is also found that higher crystallinity and uniformity of the nanocrystals could be achieved in the microwave-accelerated system.The various experimental results of the UC properties indicate that the NaYF 4:Yb 3þ,Er 3þand NaYF 4:Yb 3þ,Tm 3þnanoclusters synthesized in BmimBF 4exhibit excellent luminescent properties.Therefore,the rare earth fluoride nanoclusters are expected to be applied in solid-state laser,three-dimensional flat-panel displays,light emitting diodes,and some other optics devices.Since this IL-based and micro-wave-accelerated procedure is efficient and environmentally be-nign,it may have some potential applications in the synthesis of other nanomaterials.Acknowledgment.Grants-in-aid from NSFC (20821091,20961005,and 20971005)and MOST of China (2006CB601104)are gratefullyacknowledged.Figure 7.(a)UC luminescence spectra of R -NaYF 4:20%Yb 3þ,2%Er 3þnanoclusters in BmimBF 4and R -NaYF 4:20%Yb 3þ,2%Er 3þnanoparticles in BmimPF 6.(b)UC luminescence spectra of R -NaYF 4:20%Yb 3þ,0.2%Tm 3þnanoclusters in BmimBF 4and R -NaYF 4:20%Yb 3þ,0.2%Tm 3þnanoparticles in BmimPF 6.(c)UC luminescence photographs for 1wt %colloidal solution of R -NaYF 4:20%Yb 3þ,2%Er 3þ(left)and R -NaYF 4:20%Yb 3þ,0.2%Tm 3þ(right)nanoclusters in BmimBF 4.Figure 8.(a)UC luminescence spectra of R -NaYF 4:Yb 3þ,Er 3þnanoclusters with different doping concentrations of Er 3þ.(b)UCluminescence spectra of R -NaYF 4:Yb 3þ,Tm 3þnanoclusters with different doping concentrations of Tm 3þ.Figure 9.(a)UC luminescence spectra of R -NaYF 4:20%Yb 3þ,2%Er 3þnanoclusters with different average diameters.(b)UC luminescencespectra of R -NaYF 4:20%Yb 3þ,2%Tm 3þnanoclusters with different average diameters.。
一种微波辅助尿素水解制备ceo2 纳米实心球的方法
一种微波辅助尿素水解制备ceo2 纳米实心球的
方法
利用微波辅助尿素水解制备ceo2 纳米实心球是一种高效、快捷、绿色化的合成方法。
这种方法利用微波辅助尿素在酸性环境中把乙醇氧化为乙酸乙酯，然后迅速通过水解反应生成乙酸，乙酸又经历接下来的氧化反应生成ceo2 纳米实心球。
ceo2 纳米实心球主要有两种尺寸：直径约为300 奈米和20 奈米。
在微波辅助尿素水解方法制备ceo2 纳米实心球的过程中，一般使用的酸性溶剂主要有硫酸和氢氟酸，两种酸性溶剂都可以提高ceo2 纳米实心球的结晶度并能有效进行ceo2 的氧化反应。
然而，在水解步骤中，尿素溶液的pH 值越高，ceo2 的结晶性越低；如果把pH 值调低过多，则可能会使ceo2 过度结晶，影响微米实心球的性能。
在实验过程中，通常使用水为提取剂，把ceo2 纳米实心球从溶液中提取出来，并经过洗涤、干燥等处理。
洗涤可以去除余留的酸性溶剂，减少杂质的干扰；干燥过程可以控制ceo2 纳米实心球的粒度。
总的来说，以上微波辅助尿素水。
多元醇法合成银纳米线 ppt课件
3. Synthesis of silver nanowires based on the polyol method
• 3.1 Introduction to the polyol method • 3.2 Mechanism • 3.3 Improvements of the polyol method • 3.4 Further research
3.3 Improvements
Several key factors
Formation of MTPs :
Requiring a low concentration of AgNO3
Etching of MTPs:
Requiring reducing the effct of oxygen on the activity of MTPs
Biomdeidcal and chemical sensor
Catalysts
……
Silver nanowires rafts for trace analysis
Optical negative refraction
ppt课件
5
Jie Yao, et al.Science,2008,321,930
2.Introduction to synthesis of silver nanowires
Approaches for synthesis of silver nanowires generally fall into one of two categories:
Template-directed
PVP
微波辅助多元醇法快速制备Ag纳米线的研究
成 Ａｇ纳米 线 。考 察 了控 制 剂 、 微 波 功 率 和 反 应 时 间等条 件对产 物 Ａｇ纳米线 的影 响 ， 并对 Ａｇ纳米 线
的形成机 理进行 探讨 。
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微波辅助 多元醇法快速制备 Ａｇ纳 米线的研究
郭 瑞 萍 ，郑 敏 ，章 海 霞
（ 太 原 理 Ｔ 大学 ａ ｔ ． 材 料科 学 七 ｊ Ｔ程 学 院 ； ｂ ． 信 息 化 管 理 与 建设 中心 ； Ｃ ． 新 材 料 界 面科 学 与 丁程 教 育 部 重 点 实 验 室 ， 太原 ０ ３ ０ ０ ２ ４ ）
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探 测范 围等 。 目前 ， 如 何 制备 得 到 高 质 量 的 Ａｇ纳
米 线成 为研究 人员关 注 的热 点 。 用 于制备 Ａｇ纳米 线 的方 法 有 多 种 ， 包 括 多 元
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Ｊ （ ） ＵＲＮＡＩ ＯＦ ＴＡ１ ＹＵＡＮ ＵＮＩ ＶＥＲＳ Ｉ ＴＹ ＯＦ ＴＥ （ ： ＨＮ（ ） Ｉ （ ） ＧＹ
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文章 编号 ： １ ００ ７ ９ ４３ ２（ ２ ０１ ３） ０１ － ０ ０７ ６ － ０ ５
摘 要 ： 采 用 微 波 辅 助 多元 醇 法 ， 以 乙二 醇 为 溶 剂 和 还 原 剂 ， ＰＶＰ 为 表 面 活 性 剂 ． Ｃｕ Ｃｌ ：为 控 制
多元醇法制备CoNi纳米粒子的形成机制_尺寸控制及磁性能
秦高梧1 ,裴文利1 ,姚骋1 ,任玉平1 , Y. M . L ee2(1 .东北大学材料各向异性与织构教育部重点实验室,辽宁沈阳110004 ;2. School of Nano and A dvanced Material s Engineering ,Changwo n Nati o n al U n iver s it y , G yeo n gnam 6412773 , K orea)摘要: 采用多元醇法在150 ～190 ℃合成了C o Ni 合金纳米粒子,利用S EM2ED X , XRD 和V SM 对所制备的C o Ni 纳米粒子形貌成分结构以及磁性能进行了研究,并进一步探讨了形核剂K2 Pt Cl4 对C o Ni 纳米粒子形貌及磁性能的影响。
结果表明, 在180 ℃用多元醇法制备的C o40 Ni60 (i n at %) 纳米粒子为F CC 结构, C o2 + 要易于Ni2 + 被还原,导致最初10 mi n 内合成的C o Ni 纳米粒子中含有约78 % ( 原子分数) C o ,表现为高饱和磁化强度和高矫顽力,随着反应时间的延长, C o Ni 纳米粒子的C o 含量饱和磁化强度及矫顽力逐步下降。
在150 ～190 ℃范围内, 随着反应温度的提高,Ni2 + 的被还原能力增强,高温下合成的C o Ni 纳米粒子具有较低的饱和磁化强度和较小的矫顽力。
形核剂K2 Pt Cl4 的加入,并不影响C o Ni 合金纳米粒子的成分和晶体结构。
但是, 随着形核剂浓度的增加, C o Ni 纳米粒子平均直径明显减小,其矫顽力有所增大。
通过设计形核剂的浓度, C o Ni 纳米粒子的直径可以在96～580 n m 范围内任意控制。
关键词: C o Ni 纳米粒子;多元醇法;形核剂;磁性能相应磁性能之间的关系,至今认识有限。
是故,本研究拟通过多元醇化学法制备不同粒径的C o Ni 合金纳米粒子,研究这些C o Ni 纳米粒子的磁性能与尺寸及成分之间的关系,以期对该类合金纳米粒子的形成机理有进一步的了解。
多元醇还原制备纳米Co粉及其磁性的研究
多元醇还原制备纳米Co粉及其磁性的研究刘飚;官建国;王琦;张清杰【期刊名称】《功能材料》【年(卷),期】2005(036)007【摘要】采用二价钴盐为前驱物,1,2-丙二醇为还原剂,用液相还原法制备了晶粒尺寸约为10～13nm、具有面心立方(β相)结构的纯度高、粒度均匀的纳米钴粉,运用XRD、TEM等分析方法对制备的纳米钴粉进行物相和结构形貌的表征,初步研究了多元醇法还原Co纳米粉的反应机理.采用VSM对纳米钴粉进行磁学性能的表征.结果表明,所制备的纳米Co粉在室温下具有铁磁性,并且矫顽力不高(6.282×103A/m).【总页数】4页(P1122-1125)【作者】刘飚;官建国;王琦;张清杰【作者单位】济南大学,材料科学与工程学院,山东,济南,250022;武汉理工大学,材料复合新技术国家重点实验室,湖北,武汉,430070;武汉理工大学,材料复合新技术国家重点实验室,湖北,武汉,430070;济南大学,材料科学与工程学院,山东,济南,250022;武汉理工大学,材料复合新技术国家重点实验室,湖北,武汉,430070;武汉理工大学,材料复合新技术国家重点实验室,湖北,武汉,430070【正文语种】中文【中图分类】O613.61;TB383【相关文献】1.多元醇法制备纳米Fe3O4及其静磁性能的研究 [J], 刘飚;官建国;张清杰2.利用还原共沉淀法制备纳米四氧化三铁磁性粉体 [J], 王缓;徐利华;邸云萍;张菡3.多元醇液相还原法制备纳米α-Fe_2O_3铁粉的研究 [J], 刘战伟4.纳米洋葱碳的制备及其微波吸收特性研究FeYO3/Y2O3∶ 1% Eu3 +,1% Tb3 +粉体的制备及其磁性研究 [J], 高泽宇;王佳玮;梁颖;张卫珂;杨艳青;张玉军5.多元醇还原法制备NiPd磁性纳米合金 [J], 艾凡荣;姚爱华;黄文旵;王德平;张欣因版权原因，仅展示原文概要，查看原文内容请购买。
微波辅助合成纳米材料的研究进展
微波辅助合成纳米材料的研究进展近年来，微波辅助合成纳米材料成为了研究的热点之一。
微波辅助的特殊合成方式可以有效地实现短时间内高效率的纳米材料制备，因此已经广泛应用于材料科学和纳米科技领域。
本文将介绍微波辅助合成纳米材料的相关技术和研究进展。
一、微波辅助合成纳米材料的基本原理微波辅助合成的核心是利用微波辐射对材料的物理和化学性质进行改变，以实现快速反应和高效率合成。
与传统合成方法相比，微波辅助合成具有以下特点：1.微波辐射可以快速加热样品，在短时间内使反应体系达到高温高压条件，促进反应物分子之间的碰撞和反应。
2.微波加热可以使反应体系实现均匀加热，进一步提高合成效率和产物纯度。
3.微波加热可以减少制备过程中的能量损失，避免产生废气、废水等二次污染。
二、微波辅助合成纳米材料的技术微波辅助合成纳米材料的技术主要包括微波水热法、微波辅助溶剂热法、微波辅助溶胶-凝胶法、微波辅助凝胶转化法等。
下面将简单介绍每种技术的优缺点及适用范围。
1.微波水热法微波水热法是一种高效率、低成本和易于控制的纳米材料制备方法，主要用于合成氧化物、羟基磷灰石等无机纳米材料。
由于水的高介电常数和低损耗，微波水热反应易于实现加热、溶解和离子交换等反应。
2.微波辅助溶剂热法微波辅助溶剂热法是一种新兴的纳米材料制备方法，主要用于合成金属氧化物、金属硫化物等纳米材料，其优点在于由于微波辐射可以提高反应速率，因此可以在低温下实现高效率合成。
然而，由于需要利用有机浸润剂来辅助反应，也会造成环境污染。
3.微波辅助溶胶-凝胶法微波辅助溶胶-凝胶法是一种有效且简便的氧化物、硅酸盐纳米材料制备方法。
该方法主要步骤包括：通过水解反应制备前驱体溶胶，然后通过微波辐射处理促进溶胶凝胶和固化成型。
此法存在高效、低成本等优点，且适合制备中等温度下的氧化物、硅酸盐体系。
4.微波辅助凝胶转化法微波辅助凝胶转化法是一种涉及凝胶制备和高温烧结的复杂计算机过程，主要用于合成金属氧化物、金属硫化物、金属氟化物等材料。
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Bimetallic CoNi nanoparticles have attracted increasing attention for their potential applications in ultra-high density magnetic recording, magnetic resonance imaging, and catalysis [1–3], where their performance strongly depend on the chemical composition, size, and morphology. Compared with conventional spherical particles, CoNi nanorods and nanowires exhibited enhanced activities due to the high shape anisotropy [4,5], which clearly demonstrated that the morphology of the bimetallic nanoparticles is an essential parameter determining the magnetic properties. Spherical CoNi nanoparticles were previously reported to be highly active for methane drying reforming [6] and for growing single-walled carbon nanotubes [7], but CoNi nanoparticles with anisotropic shapes as the catalyst has not been reported.
Microwave-Assisted Polyol-Synthesis of CoNi Nanomaterials
GUO Xiaohui, LI Yong, LIU Qiying, SHEN Wenjie*
State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China
lic nanostructures with very narrow size distributions [15,16]. CuNi [17], AuAg [18], PdPt [19], AuNi [20], and NiCo [21] spherical or core-shell nanoparticles with rather narrow size distributions have been obtained by the microwave heating technique. We have previously synthesized CoNi nanorods/nanowires by a conventional hydrothermal process, but the synthesis required up to 12 h [3]. In this work, we used a microwave-assisted polyol procedure to fabricate CoNi nanourchins and nanowires in a very short time and the morphology was effectively controlled by simply tuning the temperature and heating rate.
In contrast to conventional heating methods, microwave irradiation has been applied for the rapid synthesis of metal-
646
催化学报
Chin. J. Catal., 2012, 33: 645–650
1 Experimental
1.1 Materials synthesis
Microwave heating was carried out using a multimode 2.45 GHz microwave apparatus (MARS-5, CEM Corporation). The temperature of the reaction solution was measured by a fiber optic thermometer that was directly inserted into the solution. The CoNi nanoparticles with the molar ratio of 4:1 were prepared by a heterogeneous nucleation method in 1,2-propanediol described elsewhere [3]. In a typical synthesis, 0.8 g Co(OAc)2·4H2O, 0.2 g Ni(OAc)2·4H2O, and 0.2 g NaOH were dissolved into 50 ml 1,2-propanediol, followed by the addition of 0.27 g (0.95 mmol) stearic acid and 0.02 g (0.18 mmol) RuCl3·xH2O (35 wt% Ru) dissolved in 5 ml 1,2-propanediol. Subsequently, the mixture was transferred into a flask (100 ml) and heated to the desired temperatures (140–170 oC) at 10 oC/min and kept at that temperature for 2 h. The black powders obtained was centrifuged, thoroughly washed with ethanol, and dried at 50 oC for 5 h under vacuum. The key parameters of the temperature, heating rate, and synthesis time were studied.
Abstract: Co0.8Ni0.2 nanourchins and nanowires were fabricated by microwave-assisted polyol-synthesis. Their structural evolution was monitored by powder X-ray diffraction and transmission electron microscopy measurements. The nucleation and growth rates of the crystals in their formation mechanism were discussed. Their catalytic activity for glycerol hydrogenolysis depended on their anisotropic shape and particle size. Key words: microwave-heating; polyol-synthesis; cobalt; nickel; nanowire; nanourchin; glycerol hydrogenolysis
中国科学院大连化学物理研究所催化基础国家重点实验室, 辽宁大连 116023
摘要: 利用微波辅助的多元醇法合成出纳米线和海胆状结构 Co0.8Ni0.2, 采用 X 射线衍射和透射电镜技术对该材料合成过程中
的结构变化进行了详细的研究. 根据晶体的成核与生长速率阐述了 Co0.8Ni0.2 纳米结构的形成机理. 结果表明, Co0.8Ni0.2 纳米
2012
文章编号: 0253-9837(2012)04-0645-06
Chinese Journal of Catalysis
国际版 DOI: 10.1016/S1872-2067(11)60350-1
Vol. 33 No. 4
研究论文: 645~650
微波辅助的多元醇法合成 CoNi 纳米材料
郭小惠, 李 勇, 刘琪英, 申文杰*
The control of the size and morphology during the synthesis of CoNi nanostructures has emerged as one of the most popular topics in materials science because of their magnetic and cataห้องสมุดไป่ตู้ytic properties. CoNi nanorods [4], nanowires [5], nanochains [8], nanoneedles [9], nanotube arrays [10], nanodumbbells [11], nanorings [12], and nano/micro-flowers [13] have been fabricated in the liquid phase with the aid of soft and hard templates. These advanced but, in many cases, complicated preparative techniques have greatly facilitated the shape control of CoNi nanomaterials, but they usually use conventional heating and the unavoidable temperature gradient adversely affected the particle size distribution and product yield [14].