Preparation of a carbon nanotube,carbon fiber multiscale reinforcement onto the fibers

化学气相沉积法制备多壁碳纳米管第35卷第11期2007年11月化工新型材料NEWCHEMICALMATERIALSV ol.35No.1137?化学气相沉积法制备多壁碳纳米管张璐朱红林海燕曹旭东(1.北京交通大学理学院化学所,北京100044;2.渥太华大学化学工程学院,加拿大渥太华KIN6N5)摘要以带程序升温装置的管式电阻炉为实验装置,采用化学气相沉积法,在一定的工艺条件下裂解二茂铁与双鸭山精煤的混合物制备出多壁碳纳米管.采用透射电镜,Raman光谱以及X射线衍射技术对碳纳米管产物进行袁征,同时研究了碳纳米管的生长机理.关键词碳纳米管,煤,化学气相沉积Synthesisofmulti—walledcarbonnanotubesbychemicalvapordepositionmethodZhangLuZhuHongLinHaiyanCaoXudong(1.DepartmentofChemistry,SchoolofScience,BeijingJiaotongUniversity,Beiiing10004 4;2.DepartmentofChemicalEngineering,UniversityofOttawa,Ottawa,Ontario,Canada,KI N6N5)AbstractMulti-walledcarbonnanotubes(MWNTs)weresuccessfullypreparedbychemical vapordepositionmethodwiththemixtureofferroceneandShuangyashanfinecoalasreactants.Ahorizontaltu bereactorwithaprogram- mableheatingsysthemwasusedastheexperimentalinstrument.TheMWNTsproductswere characterizedbytransmissionelectronmicroscopy(TEM),RamanspectroscopyandX-raydiffractiontechniques.Thegro wthmechanismofMWNTswasstudied.Keywordscarbonnanotube,coal,chemicalvapordeposition自碳纳米管(CNTs)发现以来_I],就以其独特的性质和潜在的应用前景引起了人们的广泛关注.有关CNTs的制备以及表征已经有大量的报道.CNTs的制备方法包括电弧法_2],激光蒸发法_3],化学气相沉积法(C,厂D)]等.其中,前两种方法需要较高的温度条件,制备的CNTs质量好,然而产量低,不适合工业化生产.相反,人们已证明CVD法可以用来大规模制备CNTs,它所需要的温度也相对较低(550～IO00~C)E.本研究采用CVD法,以带程序升温装置的管式电阻炉为实验装置,在一定的工艺条件下裂解二茂铁与双鸭山精煤的混合物制备多壁碳纳米管(MWNTs),同时研究了CNTs的生长机理.1实验部分1.1煤样固定碳和挥发分是表征煤中主要成分有机质性质的主要工艺性指标,灰分是煤中矿物质含量多少的度量指标_8].一般认为煤中固定碳含量高,意味着在化学气相沉积法中参与纳米碳材料形成的活性碳离子浓度高,从总体上有利于碳纳米管的形成.本方法采用的双鸭山精煤的固定碳含量达8O以上.对煤样进行粉碎,过140目筛.1-2化学气相沉积制备MWNTs反应装置是带有程序升温装置的管式电阻炉.其结构如图1所示.石英管的内径为18ram,长度为ll0cm.管式炉的有效温度区为300ram,位于石英管的中间部位.图1煤制多壁碳纳米管的实验装置图oeouples取适量精煤,与二茂铁以质量比1:3均匀混合,将其装入瓷舟中,再将瓷舟放入石英管的中央部位(反应区),通Nz50mL/min约15min排空.设置好反应时间3h和反应温度1000~C,开始加热.整个实验过程在N2保护下进行.实验结束后,在石英管管壁上及瓷舟中收产物.1.3M的表征用透射电镜(TEM,JEM-2010)观察碳纳米管粗产物的形貌,尺寸和结构.用Raman光谱(RenishawRM2000,632.8基金项目:国家863项目(2006AA03Z226);北京自然科学基金(29051001);国际合作项目(2OO6DFA6124O)作者简介:张璐(1985一),女,在读硕士,主要从事碳纳米管的研究.38化工新型材料第35卷nlTlHe-Nelaser)对产物的结构进行表征.产物的物相组成通过x射线衍射(XRD,XD-D1)观察.2结果与讨论为了研究碳纳米管的生长机理,采用TEM对产物进行表征,如图2所示.从图2a可以看出,有大量碳纳米管生成,同时存在一些杂质如催化剂颗粒和无定形炭等;图2b是单根碳纳米管的透射电镜图.可以看出,管径分布较均匀,碳管的端部封闭,含有金属催化剂颗粒,碳管管体中也存在一些金属颗粒,说明金属颗粒的催化作用可以在两侧同时进行,在制备过程中这些颗粒受到来自两侧的推力,被包覆在管体中_g,并造成碳管在颗粒处拐弯和变形的现象,如图2c所示.从图2c也可以看出,生成的碳管为MWNTs,碳管的内径和外径分布范围分别在4~10nm,24~40nm之间.图2碳纳米管的TEM图图3是碳纳米管的Raman光谱图.Raman光谱在1593.8cm处的G峰表明,制备的碳纳米管为MWNTs,与透射电镜的结果一致,这是由两个E2拉曼活性振动模式产生.G峰指示的是有序的石墨层结构;而出现在1329.2cm1处的D峰,由拉曼非活性呼吸振动模式A1造成的.它指示石墨层结构上的缺陷(不封闭的端口,无定形炭等)l】.两峰的强度比Ig/Id~l,说明合成的MWNTs有较大的缺陷,含有无定性炭等杂质,与TEM结果一致(图2所示),在其它以Fe为催化剂采用CVD法制备碳纳米管的文献中也有类似的发现_】3_. 没有出现呼吸振动峰(RBM),说明产物中没有单壁碳纳米管生成,进而说明该方法的合成选择性高.鼍想魑图3碳纳米管的Raman光谱碳纳米管粗产物的XRD谱图见图4.在20—26.处,该峰是碳纳米管的特征峰(002),它对应于石墨层片的间距0.34nm,说明MWNTs的层间距约为0.34nm.在20~45.左右,还发现了很强的峰,它是Fe和Fe3C的重叠峰.此峰的强度比碳纳米管的特征峰的强度高很多,说明产物中金属杂质占很大的比例.为了研究碳纳米管的生长机理,在相同的温度和时间条件下分别对二茂铁与精煤做了空白实验.TEM表征结果发现,单独裂解精煤时,产物中几乎没有碳纳米管;而单独裂解二茂铁时,产物中有许多纳米碳管,与裂解二者的混合物相比,该碳管的管长较短,管径较粗,约为6O～100nm;产物中也含有更多无定性炭,金属催化剂颗粒等杂质.该结果说明,采图4碳纳米管的XRD图用CVD法裂解二者混合物制备碳纳米管过程中,二茂铁作为催化物前驱体,在高温下分解出纳米级Fe原子和C原子,这两种原子形成Fe-C的固溶体,然后C原子从过饱和的固溶体析出,长出碳管;同时,Fe原子的催化作用是在碳管两侧同时进行的,导致生成的MWNTs管壁上缺陷多,石墨结构不完整,如图2和图3所示.精煤是许多有机和无机化合物的混合物,这些物质的化学结构间存在弱键,在一定条件下可断键释放出一系列烃类活性组分如烷烃和芳香烃等l2].在金属催化剂Fe原子的作用下,活性组分为CNTs的生长提供碳源此外,煤中含有较高含量的灰分物质表明,它可以提高纳米碳管的石墨化程度并促进金属的催化作用以致提高碳管产率[1415].裂解精煤与二茂铁混合物所得碳管形貌比单独裂解二茂铁所得碳管形貌好,杂质含量少,说明精煤中含有的灰分物质对碳管生长也起促进作用.3结论采用化学气相沉积法,在反应时间为2h,温度为1000℃,精煤与二茂铁的质量比为1:3的条件下,裂解精煤与二茂铁的混合物制得MWNTs.研究MWNTs的生长机理结果表明,二茂铁作为催化剂前驱体同时为碳纳米管的生长提供碳源;精煤既作为碳源,同时煤中含有的灰分物质在碳纳米管的生长过程中起到了重要作用.第11期张璐等:化学气相沉积法制备多壁碳纳米管?39?参考文献[1]Iijimas.Helicalmicrotubulesofgraphiticcarbon[J].Nature, 1991,354(7):56.L1OJ[2]JieshanQiu,ZhiyuWang,ZongbinZhao,eta1.Synthesisofdouble-walledcarbonnanotubesfromcoalinhydrogen-freeat一[111 mosphere[J].Fuel,2007,86:282—286.[3]程大典,余荣清,刘朝阳,等.碳纳米管的激光溅射产生[J].高等学校化学,1995,16(6):948—949.[121[4]ChengHM,LiF,SuG,etaLLarge-scaleandlow-costsyn—thesisofsingle-walledcarbonnanotubesbythecatalyticpyroly—sisofhydrocarbons[J].ApplPhysLett,1998,72:3282—3284.L13] [5]陈萍,王培峰,林国栋,等.低温催化裂解烷烃法制备碳纳米管[J].高等学校化学,1995,16(11):1783—1784.[6]孙晓刚,曾效舒.化学气相沉积法制备多壁碳纳米管研究[J]. 中国粉体技术,2002,8(5):34—36.L14j[7]DasguptaK,RamaniV enugopalan,SathiyamoorthynThe productionofhighpuritycarbonnanotubeswithhighyieldu—singcobaltformatecatalystoncarbonblack[J].MateLett,Ll5J 2007.,[8]邱吉山,韩红梅,周颖,等.由两种烟煤制备碳纳米管的探索性研究[J].新型炭材料,2001,16(4):1-5.GiuseppeG,RicardoV,JulienA,eta1.C2H6asanactivecar—bonsourceforalargescalesynthesisofcarbonnanotubasby chemicalvapordeposition[J].ApplCatal,2005,279:89—97.田亚峻,谢克昌,攀友三.用煤合成碳纳米管新方法[J].高等学校化学,2001,22(9):1456—1458.BakerRTK,HarrisPS,ThomasRB,eta1.Forraationof filamentouscarbonfromiron,cobaltandchromiumcatalyzed decompositionofacetylen[J].Catal,1973,30:86—95. KasuyaA,SakakiY,SaitoY,eta1.Evidenceforsize-depend—entdiscretedispersionsinsingle-wallnanotubes.PhysRevLett,1997:78:4434.QiuJS,AnYL,ZhaoZB,eta1.Catalyticsynthesisofsingle-walledcarbonnanotubesfromcoalgasbychemicalvapordepo—sitionmethod[J].FuelProcessingTechnology,2004,85:913—920.SaitoY,NakahiraT,UemuraSGrowthconditionsofdouble- walledcarbonnanotubesinarcdischarge[J].JPhysChem,2003,107(B):931—934.LiHJ,GuanLh,ShiZJ,eta1.Directsynthesisofhighpurl—tysingle-walledcarbonnanotubesfibersbyarcdischarge[J].J PhysChem,2004,108(B):4573—4575.收稿日期:2007-06-29lllllllllllllllllllllllllllllllllllllll,llllllllllllllllllllllllllllllllllllllllllllllllllllllll (上接第36页)因此可以预测,用NHFePO4作为前驱体来制备LiFePO4可行的,而且将会很好地改善LiFePO4电池的电化学性能.邑{嘤波数/era图1样品的FTIR谱图20/(.)图2样品的XRD谱图一■a)最佳:I艺条件的样晶(b)正交宴验l的样品图3样品的SEM谱图图3是NH4FePO4的SEM谱图,样品(a)是最佳工艺条是件下制备的材料,样品(b)是按正交实验1的条件所制备的材料.从图中可以看出,样品(a)颗粒基本上是球形颗粒,平均粒径为1.6m,通过测试,其振实密度为1.73g/cm3.而样品(b)则是以不规则形状的颗粒为主,其振实密度也只有1.57g/cm3.3结论(1)用共沉淀法成功地合成出球形NH4FePO4.(2)用正交实验得到了共沉淀法合成NHFePO的最佳工艺条件:pH值为5.5,混合液流速为225mL/h,搅拌速度为120r/min,Fe浓度为1.0mol/L,反应体系温度为45.C,柠檬酸用量为混合液体积的6,NHs?HzO浓度为2.0mol/L.(3)在最佳工艺条件下,所得到NHFePO4的振实密度达到1.73g/cm3,为球形颗粒.参考文献[1]Y angSF,SongYN,NgalaK,eta1.PerformanceofLiFeP04 aslithiumbatterycathodeandcomparisonwithmanganeseand vanadiumoxides_J].PowerSources,003,119:239—246.[2]HuangH,YinSC,NazarLF.Approachingtheoreticalcapac—ityofLiFePO4atroomtemperatureathighrates[J].Electro—chemicalandSolid—Stateletters,2001,10(4):A170一A172. [3]ParkKS,SonJT,ChungHT,eta1.Surfacemodificationby silvercoatingforimprovingelectrochemicalpropertiesofLiFe—PO4_J].SolidStateCommunications,2004,129:311-314.[4]ProsiniPP,CarewskaM,ScacciaSLong—termcyclbilityof nanostructuralLiFePO4rJ_.ElectrochemicalActa,2003.48: 4205—4211.[5]卢俊彪,唐子龙,张中太,等.镁离子掺杂对LiFePO4/C材料电池性能的影响[J].物理化学,2005,21:319—323.[6]吴江,宋志方,罗新文,等.MH—Ni电池正极材料球形氢氧化镍的研究[J].江西化工,2005,3;75—78.收稿日期:2007-06-20《,。

图 1 帕洛诺怀琼合成路线Fig.1 The s ynthe s i s ronte of pa l onos e t i on盐 酸帕洛诺司琼的 合 成* 杜有国，胡 振，宗在伟（江苏奥赛康药业有限公司，江苏 南京 211112）摘要： 合成新型 5-HT 3 受体阻滞剂。

以（S ）-1，2，3，4- 四氢 -1- 萘甲酸为起始原料，经酰化、缩合、还原、环合、成盐等反应合成盐酸帕洛诺司琼，总收率达 36.2％。

该法工艺操作简便，反应条件温 和，适合工业化生产。

关 键 词： 抗肿瘤药；盐酸帕洛诺司琼；药物合成 中图分类号： TQ 463文献标识码： A文章编号： 1671-0460（2010）01-0014-03帕洛诺司琼（palono s etron ），由瑞士 Helsinn公司研发的化合物选择性 5- 轻色胺受体拮抗 剂，2003 年 7 月 25 日获美国 FDA 批准用于预防 中至高度致呕性化疗引发的急性和迟发性恶心 呕吐，2 个月后在美国首次上市。

本品在上市后 第二个季度就被卫生界人士和癌症患者广泛接 受，很快成为预防恶心和呕吐的首选药。

关于盐 酸帕洛诺司琼的合成目前已有一些文献报道，在专利方面国内外只有不多的报道[1-4]。

文献工艺各 有不足，文献[1] 氢解和加氢都比较难，氢解时萘 甲酸原料中含有的金属容易毒化催化剂，加氢时 条件难以控制，反应的选择性不高；此路线还要 用到丁基锂，这对于工业化生产也是一个障碍。

文献[2，3] 此路线也存在加氢时条件难以控制，反 应的选择性不高的缺点。

参考文献[3] 设计了一条 新的合成路线，其每步反应操作比较简单，不需 要特殊的反应装置，合成难度小，易于工业化生 产。

新路线以（S ）- 1，2，3，4- 四氢 - 1- 萘甲酸为 起始化合物，这是由于原先路线中由四氢萘合成 （S ）- 1，2，3，4- 四氢 - 1- 萘甲酸合成时间长，反 应条件苛刻，如要求低温，且反应试剂如正丁基 锂极易自燃，对操作要求较高，而且收率低。

外刊精读让马拉松变得更环保导读：似乎在世界各地，每个主要的大城小镇都会举办年度马拉松比赛。

成千上万的参赛运动员要经受艰难的体能考验，跑完42.1 公里的赛程。

和其它大型比赛一样，马拉松比赛也会产生大量的碳足迹。

数千人乘坐飞机前来参赛或观赛，观众和运动员留在赛道的食物垃圾、包装袋、礼品袋等等。

本期《外刊精读》讨论相关部门针对马拉松比赛所采取的各项环保措施。

一、语篇泛读Even if you’re a couch potato like me, you’ll know the benefits of running - pounding the pavements, working up a sweat, burning off some calories and generally keeping fit. But if you’re a real fitness junkie, the ultimate running challenge is to take part in a marathon.It seems every major city and town aro und the world hosts an annual marathon, with thousands of athletes running a gruelling 42.1 kilometers. Whilst many runners’ motivation is to beat their personal best and cross the finishing line without collapsing, they’re also doing it for a good cause– to generate funds for charity. But like other major events, the marathon also generates a massive carbon footprint. Thousands travel - some by plane - to the location, and waste from food packaging and goody bags gets left behind by spectators and runners. For example, during the London Marathon in 2018, 47,000plastic bottles were collected, although some were recycled.This is becoming a big issue for cities –how to host a worthwhile event, encouraging people to exercise and help charities, whilst protecting the environment? Several cities have developed formal plans to reduce their environmental impact and promote sustainable ideas. One event in Wales, for example, introduced recycling for old running kit and ethically sourced the race t-shirts.It’s something that this year’s London Marathon tried to tackle by reducing the number of drink stations on the running route, giving out water in paper cups and offering some drinks in edible seaweed capsules. They also trialed new bottle belts made from recycled plastic so 700 runners could carry water bottles with them during their run. London Marathon event director Hugh Brasner told the三、测试与练习阅读课文并回答问题。

DICP Course -Dalian, 2012Preparation of solid catalystsExercisesSupported by the Chinese Academy of Sciences Charles Kappenstein, Professor Emeritus, University of Poitiers, FranceEx.1. A transition alumina support has been prepared; the determination of the specific surface area (S BET ) and the porous volume (V p ) gave the following results:S BET = 200 m 2g -1V p = 1 mL g -1a) Calculate the size of the pores (hint: use the cylindrical pore model with constant diameter)b) Is this alumina microporous, mesoporous or macroporous?c) What is the accuracy of the experimental data? (hint: the accuracy can beexpressed as estimated relative standard deviation)Ex.2. A transition alumina support display a specific surface area S BET = 180 m 2g -1. It is used for the preparation of platinum supported catalysts Pt/Al 2O 3.The maximum loading of H 2PtCl 6precursor is: 1.6 µmol m -2.The number of surface hydroxyl groups is 8 OH nm -2.a) Compare the number of surface OH groups able to adsorb the precursor to the total number of surface OH groups (assumption: the adsorption need one OH group per precursor molecule).b) Describe the different steps of the preparation procedure.c) Determine the maximum platinum loading (in term of mass percentage) that can be reach at the end of the catalyst preparation.d) What would you suggest for the surface loading for 10 g of support? Calculate the initial pH for different surface loadings. Conclusion.Ex.3. We have prepared a catalyst Ir/Al 2O 3for the decomposition of hydrazine for space propulsion. The characteristics of the catalyst are:wt.-% Ir = 40 %Specific surface area of the support = 100 m 2g -1Porous volume = 0.7 mL g -1Ir crystallite size = 2 nma) Estimate the pore diameter of the supportb) Calcultate the distance x 1of Ir particles center to center on the surfacec) Calculate the distance x 2of Ir particles center to center in the porous volumeEx.4. Preparation of a copper catalyst on silica (200 m 2g -1)We prepare a solution containing the complex tetraamminecopper(II) [Cu(NH 3)4]2+by adding commercial concentrated ammonia (28 wt.-%, density 0.898 kg L -1)to 50 mL of an aqueous solution containing copper nitrate 0.2 mol L -1; the final pH is 12.The pK a of the acid-base couple NH 4+/NH 3is 9.25 at 25 °Ca) Concentration of the commercial ammonia solution?b) Concentration of ammonia in an aqueous solution of pH 12 at 25°C?c) Volume of the commercial ammonia solution to be to be added to reach pH 12?d) Final volume, concentration of copper and pH? ConclusionExercice4 (cont’d)Ex.4. Preparation of a copper catalyst on silica (200 m2g-1)We dip 8.5 g of silica into the solution at room temperature and maintain agitation for 2 h. Then we remove the impregnated support by filtration, wash with water, dried, then calcined under air at 300 °C. We observe that 57 % of initial copper remains on the support as CuO.e) How can we obtain experimentally this value?f) Describe the silica surface in ammonia solution? Compare with the aqueous solution.g) What happen in the presence of the copper complex; what is the best procedure to impregnate silica? What is the surface density of copper complex(in nm-2)?h) Determine the wt.-% of CuO and Cu in the sample. How can we obtain experimentally this value?A sample of 100 mg is followed by H2TPR. At 300 °C, the H2consumption is 1.44 cm3(20°C, 1 bar); at 500 °C, the H2consumption is 1.55 cm3(20 °C, 1 bar)i) Determine the reduction rate for copper at both temperatures. What is the final wt.-% of Cu in the sample?Ex.5. Study of a silica-supported copper catalyst Cu/SiO2Cu cubic cell, Bravais lattice F, a = 3.6147 Å= 1 wt.-% Cu Dispersion = 10 %Loading level xma) Determine: (i) the diameter of a copper atom, (ii) the atom surface density for the threefaces (100), (110) and (111), (iii) the mean density, and (iv) the average distance LCu between two Cu atoms.b) Determine: (i) the surface area of copper A(m2g-1), (ii) the size of the coppermparticles d (nm), (iii) the number of copper particles (g-1), the perimeter of the interface metal/support (hint: cubic particles with one face in contact with support, edge length d, surface density = mean density).c) Calculate: (i) the total number of copper atoms present in one particle; (ii) the number and percentage of Cu atoms on the free edges and corners; (iii) the number and percentage of Cu atoms on the free faces and (iv) the number and percentage of atoms in contact with the support.Ex.6. Characterization of a silica-supported copper catalyst Cu/SiO 2hydrogen is adsorbed on copper at 25 °C without dissociation; the adsorption enthalpy is close to -40 kJ mol -1.a) Can we use hydrogen to determine the number of surface Cu atoms?Nitrous oxide decomposes on copper between 25 and 80 °C following the reaction:N 2O(g) + 2 Cu(surface) Cu-O-Cu(surface) + N 2(g)Using 150 mg of the catalyst, we obtain 0.43 cm 3N 2(STP). Take data from Ex. 4.b) Determine the dispersion of copper and the metallic surface area.c) Calculate the size of the copper particles.d) We use electron microscopy; how many copper particles can we expect to see on a picture 200 nm x 200 nm?The copper atoms in contact with the support are more difficult to reduce. e) How ca we explain the TPR results?Ex.7. Preparation of a Rh/Al 2O 3catalystThe rhodium precursor is "RhCl 3⋅xH 2O" and contains 39.2 wt.-% Rh.50.00 g alumina are dip in 100 cm 3of aqueous HCl 0.100 mol L -1. Then, 1.00 g of precursor RhCl 3⋅xH 2O is added and the mixture is stirred for 1 h. After filtration, the impregnated alumina is dried at 120 °C for 6 h. The sample contains 1.10 wt.-% Cl.a) Determine the value of x in the precursor formula.b) With the assumption that all the precursor has been adsorbed onto the alumina, calculate the wt.-% for Cl and Rh. Explain why the experimental value for Cl is different. Explain why this precursor is able to be adsorbed quantitatively in acidic conditions.The dried catalyst is reduced (1 vol.-% H 2in Ar, 300 °C, 20 cm 3min -1, 1 h) and characterized by H-chemisorption at 20 °C. The hydrogen uptake is 0.62 cm 3g -1(STP)c) Determine the rhodium dispersion (hint: 1 surface Rh atom can adsorb 1 H atom)d) Calculate the metallic area (1 Rh atom, 7.9 Å2)and the average size of Rh particles (cubic model)Exercice 7 (cont'd)Ex.7. Preparation of a Rh/Al 2O 3catalyst。

小学上册英语第4单元真题试卷英语试题一、综合题(本题有100小题，每小题1分，共100分.每小题不选、错误，均不给分)1.The ______ can live a long time.2. A silverfish is a type of ________________ (昆虫).3.I have a _______ (surprise) for you.4.Catalysts can significantly speed up reaction rates without being _____ in the process.5.In a reversible reaction, reactants can form products and _____ can reform the reactants.6.In spring, the _____ blooms beautifully.7.What is the name of the ocean located on the east coast of the United States?A. Atlantic OceanB. Pacific OceanC. Indian OceanD. Arctic OceanA8.The Earth's core is primarily made up of ______ and nickel.9.I can ______ (展示) my talents.10.The chemical formula for copper(II) sulfate is _____.11.My dad teaches me to be __________ (负责任的) in my actions.12.What do you call a person who repairs cars?A. MechanicB. ElectricianC. PlumberD. PainterA13.My favorite ________ is pink.14.The antelope grazes on the _____ grass.15.The __________ is a famous landmark in Paris.16.My _____ (叔叔) works at a zoo and takes care of the animals. 我叔叔在动物园工作，照顾动物。

碳化硼的研究进展刘珅楠;孙帆;谭章娜;袁青;周凯静;马剑华【摘要】碳化硼是高性能陶瓷材料中的一种重要原料，包含诸多的优良性能，除了高硬度、低密度等性能外，它还具备高化学稳定性和中子吸收截面及热电性能等特性，在国防军事设备、功能陶瓷、热电元件等诸多领域具有十分广泛的应用。

本文重点介绍了碳化硼的相关性质、研究进展和应用现状。

详细地介绍了碳化硼的制备方法，如电弧炉碳热还原法、自蔓延高温法、化学气相沉积法、溶胶-凝胶法等方法，并分析了它们的优缺点。

%Boron carbide is a kind of important raw materials of high performanceceramic material, including many excellent performance. In addition to highhardness and low density properties, it also has high chemical stability andneutron absorption cross section and thermoelectric properties, which are widely used in national defense and military equipment, functional ceramics and thermoelectric element fields. The current research progress and application of relevant properties, boron carbide were introduced. The preparation methods of boron carbide, such as carbon arc furnace reduction method, self-propagating high temperature method, chemical vapor deposition, sol-gel method, were mainly introduced, and their advantages and disadvantages were analyzed.【期刊名称】《广州化工》【年(卷),期】2015(000)005【总页数】3页(P21-23)【关键词】碳化硼;特种陶瓷;自蔓延高温法;化学气相沉积法;溶胶-凝胶法;前驱体【作者】刘珅楠;孙帆;谭章娜;袁青;周凯静;马剑华【作者单位】温州大学化学与材料工程学院，浙江温州 325000;温州大学化学与材料工程学院，浙江温州 325000;温州大学化学与材料工程学院，浙江温州325000;温州大学化学与材料工程学院，浙江温州 325000;温州大学化学与材料工程学院，浙江温州 325000;温州大学化学与材料工程学院，浙江温州 325000【正文语种】中文【中图分类】TQ263.1材料是人类社会赖以生存和发展的物质基础。

Materials Chemistry and Physics99(2006)80–87Effective preparation of carbon nanotube-supportedPt–Ru electrocatalystsChun-Ching Chien∗,King-Tsai JengInstitute of Nuclear Energy Research(INER),P.O.Box3-19,1000Wenhua Road,Longtan,Taoyuan325,TaiwanReceived1June2005;received in revised form31August2005;accepted30September2005AbstractCarbon nanotube(CNT)-supported electrocatalysts,such as Pt/CNT and Pt–Ru/CNT,have been intensely studied recently for membrane fuel cell applications.These novel electrocatalysts were generally prepared by chemical reduction deposition using ethylene glycol(EG)as a reducing agent.However,due to different metal deposition conditions,CNT-supported binary and multi-component electrocatalysts cannot be prepared using EG alone with satisfactory results.In this study,an effective method for preparation of CNT-supported Pt–Ru alloy electrocatalysts has been developed.Suitable amounts of sodium hydrogen sulfite(NaHSO3)and calcium hydroxide aqueous solutions were employed as additives to EG forming a modified reducing agent.This new approach was based on the use of more suitable Pt–Ru deposition environments created by the modified EG near the isoelectric point(IEP)on the acid-oxidized CNT surfaces.It gave rise to enhanced formation of Pt–Ru/CNT with high metal deposition efficiency,excellent nanoparticle morphology and desired electrocatalyst composition.In addition,the prepared Pt–Ru/CNT exhibited high methanol electrooxidation activity in0.5M H2SO4aqueous solution better than that of a carbon black-supported commercial product.Overall, preparation of Pt–Ru/CNT using the modified EG resulted in much better electrocatalyst formations than those prepared using a variety of common reducing agents.©2005Elsevier B.V.All rights reserved.Keywords:Alloys;Nanostructures;Electrochemical properties;Adsorption1.IntroductionMembrane fuel cells,particularly direct methanol fuel cells (DMFCs),are regarded as potential mobile power sources due to high energy density,easy operation and simple fuel supply. However,DMFCs strongly depend on the use of Pt electrocat-alyst for effective oxygen reduction and Pt–Ru electrocatalyst for methanol fuel electrooxidation.The use of binary or multi-component electrocatalysts for methanol electrooxidation is to solve the catalyst poisoning problems caused by CO and other reaction intermediates under low temperature reaction condi-tions.Conventionally,highly conductive carbon blacks,such as Vulcan XC72(Cabot)and Shawinigan(Chevron),with high surface areas are used as supports for electrocatalysts to ensure large electro-reaction surfaces and good electronic conduction. Although such carbon black-supported electrocatalysts have exhibited moderate performances on DMFCs so far,new elec-∗Corresponding author.Tel.:+88634711400x5038;fax:+88634711410.E-mail address:ccchien@.tw(C.-C.Chien).trocatalyst carbon supports,such as carbon spheres[1],graphite nanofibers[2],carbon nanohorns[3]and carbon nanotubes [4–6],are actively being sought with attempts to significantly improving fuel cell performances.In particular,more and more carbon nanotubes(CNT)have been investigated[7–11]recently as advanced electrocatalyst supports due to their distinctive characteristics.Although several preparation methods are feasible,most CNT-supported electro-catalysts reported so far were prepared using chemical reduction deposition methods.A variety of common reducing agents,e.g. HCHO,HCOOH,NaBH4,NaH2PO2,N2H4,etc.,can be used to convert metal ions into metal particles and deposit onto CNT surfaces.However,Lordi et al.[12]were thefirst to report successful preparation of nanosized Pt particles supported on single-walled CNT as a heterogeneous catalyst using a polyol process.At present,reductive preparation of CNT-supported electro-catalysts using ethylene glycol(EG)as a reducing agent seems to be the most popular approach[4–7].In such a polyol process, CNTs were generallyfirst subjected to oxidation pre-treatment [12]using a strong acid,such as HNO3or mixture of HNO30254-0584/$–see front matter©2005Elsevier B.V.All rights reserved. doi:10.1016/j.matchemphys.2005.09.080C.-C.Chien,K.-T.Jeng/Materials Chemistry and Physics99(2006)80–8781and H2SO4,solution so as to remove impurities and generate sufficient amounts of functional groups,such as OH,COOH, C O,etc.,on the surfaces.These surface functional groups have stronger attraction forces toward metal ions than bare carbon nanotube surfaces and some even have ion exchange capabilities,such as carboxylic acid groups.Therefore,they are believed to work as metal-anchoring sites in order to facilitate metal nuclei formation and electrocatalysts deposition.In fact, this process is somewhat similar to electroless deposition that requires some imperfect sites on the substrate surfaces to anchor and hold the reduced metals.However,EG is only a mild reducing agent requiring a long reaction time for involved reduction reactions to go to comple-tion even for the preparation of Pt/CNT.Its reducing strength, or power,may be strong enough for reduction of Pt ions but a little bit too weak for the reduction of Ru ions.In addition,in the preparation of Pt–Ru/CNT difficulties arise that Pt and Ru ions cannot be reduced simultaneously at the same pH of the reac-tion solution with competitive reduction rates using EG alone. For example,a high pH value(pH>13)of the EG solution was reported to be favorable for Pt formation on CNT[4]but this is,in fact,not an acceptable condition for Ru formation.It was found in our experiments that once the pH of the EG solution is adjusted to a value higher then4undesirable precipitates,includ-ing Ru(OH)3,of Ru salts appear.The reduction reactions of such precipitates are difficult to proceed leading to large particle size formation,low metal deposition,non-uniform dispersion and undesirable electrocatalyst composition on CNT and,in turn, resulting in poor performance with respect to methanol elec-trooxidation.As a result,Pt–Ru/CNT cannot be readily prepared by the same polyol procedure as that of Pt/CNT with satisfactory results.The shortcoming of EG to have a poor reducing power may be overcome by the use of more active reducing agents,such as sodium borohydride and formaldehyde,to enhance reduction reactions.However,our experience indicated that Pt–Ru/CNT prepared by reduction with conventional active reducing agents tends to form large agglomerates and incorporate impurities,e.g. boron oxides,leading to poor catalytic activity on methanol elec-trooxidation.Other feasible approaches to prepare Pt–Ru/CNT include electrodeposition[5,13],wet impregnation followed by chemical reduction[14],metal vapor deposition[15],etc.,but large particle formation and poor catalyst morphology are com-mon drawbacks.Innovative approaches are urgently needed to solve these problems.In this study,an effective preparation method was sought using modified reducing agents.The strategy was to enhance the reducing strength of EG and modify the reaction environments so that ligand-complexed Pt and Ru ions can be simultaneously reduced at the same low pH range,e.g.pH2–4,with competitive specific rates and without preferences in the formation of any specific metal or undesirable precipitates,and at the same time to maintain those good characteristics of EG as a reducing agent in electrocatalyst formation on CNT.To realize this idea,the fea-sibility was resorted to the concept of potential of zero charge (PZC)for a double layer structure at a CNT/solution interface or,more precisely,the isoelectric point(IEP)for aflow system as in our case with reactions proceeding under high-speed stir-ring conditions.At such a specific point,no net charge occurs on the CNT surfaces and,therefore,Pt and Ru can be deposited at competitive specific rates due to similar specific adsorption rates for different ions.Thus,suitable additives were investigated as modification agents to EG in order to bring about the occur-rence of IEP under proper deposition conditions.In addition, microwave irradiation,with fast and even heating capability, and ultrasound sonication were employed to enhance reductive reactions so that the metal deposition process can be completed in a shorter time with significantly improved results in terms of electrocatalyst formation for preparation of Pt–Ru/CNT.The prepared Pt–Ru/CNT electrocatalysts were tested for methanol electrooxidation in0.5M H2SO4solution.Investigations on using a variety of reducing agents different from EG as well as using electrodeposition method for the preparation of CNT-supported Pt–Ru electrocatalysts were also carried out.The results were analyzed and compared.2.Experimental2.1.Preparation of CNT-supported Pt–Ru electrocatalystsMulti-walled carbon nanotubes were obtained from Advance Nanopower Inc.,Taiwan having diameters of8–15nm and a high surface area of233m2g−1. The as-received carbon nanotubes werefirst oxidized in a hot solution,composed of8M HNO3and2M H2SO4,for several hours under refluxing conditions to remove impurities and generate surface functional groups.Purification of CNT surfaces prevents self-poisoning by foreign impurities while functional group generation enhances electrocatalyst formation.Examination on surfaces of acid-oxidized carbon nanotubes was carried out using a Fourier transform infrared (FT-IR)spectrometer(Bio-Rad,FTS-40)to ensure formation of desired surface functional groups.Reagent grade reducing agents,i.e.ethylene glycol and NaHSO3solution, were obtained from Merck and electrocatalyst precursor salts,i.e.H2PtCl6·6H2O and RuCl3,were purchased from Alfa Aesar.They were used as received with-out further purification.The procedure employed for reduction deposition of Pt–Ru electrocatalysts on pre-treated CNT is illustrated in Fig.1.It is similar to those reported previously by other groups[9,16]using a microwave irradia-tion heating method to significantly shorten the reaction time.However,proper modification of the EG reducing agent has been conducted as a main focus to suit the reaction condition for Pt–Ru/CNT formation.As an example,in the preparation of20wt.%Pt–10wt.%Ru/CNT,1.65g of acid-oxidized CNT was added to50ml of EG.The above mixture was sonicated for10min followed by high-speed stirring,using a high-speed stirrer(Heidolph,Silent Crusher M),for 30min to form a homogeneous paste so that EG was able to completely cover the carbon nanotube surfaces.Then,1.264g of H2PtCl6·6H2O and0.506g of RuCl3as Pt–Ru electrocatalyst precursors were dissolved in10ml EG together with aqueous solution of1ml of1M NaHSO3and about0.1ml of1000ppm Ca(OH)2.Thefinal pH was adjusted to about2–4.After this,the solution was slowly added to the prepared CNT/EG paste and subjected to high-speed stirring for at least30min for complexed metal ions to adsorb onto the surfaces of car-bon nanotubes followed by formation of Pt–Ru electrocatalyst through chemical reduction reaction.The resultant mixture was then heated at70–140◦C using a microwave heater for10–120min for the reduction reaction to go to com-pletion.In the preparation of Pt–Ru/CNT,the amounts of precursor salts,i.e. H2PtCl6·6H2O and RuCl3,were used with an atomic ratio(Pt:Ru)of about1:1.After reduction reaction,the reacted mixture wasfiltered and the collected carbon nanotubes were washed and rinsed with a sufficient amount of Millipore water(resistivity>16.0M cm).Thefiltrate and wash wastewater were analyzed using an inductively coupled plasma–optical emission spectroscope(ICP–OES) (Jobin Yvon,Ultima-2)to determine the total amounts of un-reacted metal ions and washed out metal ions and particles.Then,the actual amounts of metals supported on CNTs were calculated.Finally,the electrocatalyst-loaded carbon82 C.-C.Chien,K.-T.Jeng/Materials Chemistry and Physics99(2006)80–87Fig.1.A schematicflowchart illustrates the procedure for preparation of CNT-supported Pt–Ru electrocatalysts using the modified EG.nanotubes were dried in an oven at100◦C under vacuum condition for sev-eral hours.Preparations of CNT-supported electrocatalysts using other reducing agents were conducted in a similar manner.2.2.Physical characterization and electrochemical investigationon methanol electrooxidationPhysical characterization of the prepared Pt–Ru/CNT electrocatlysts was conducted using a transmission electron microscope(TEM)(JEOL,JEM2010 operating at200kV)for morphology and particle size analyses and a scanning electron microscope(SEM)(JEOL,JSM-T330A operating at20kV)with energy dispersive spectrocopy(EDS)capability for elemental analyses.Electrochem-ical investigations on the prepared Pt–Ru/CNT electrocatalysts with respect to methanol electrooxidation were carried out using cyclic voltammetry.For all the electrochemical tests,the same amount of electrocatalyst(0.5mg)was used each time.Each sample was mounted on a glassy carbon electrode(0.196cm2) andfixed with0.1ml of5wt.%Nafion solution.A three-electrode system was employed with Pt as a counter electrode and Ag/AgCl as a reference electrode. Methanol electrooxidation experiments were performed at room temperature in 0.5M H2SO4aqueous solution containing1.0M CH3OH.3.Results and discussion3.1.Oxidative treatment of carbon nanotube surfaces usinga strong acid solutionThe carbon nanotubes used in this study were prepared by cat-alytic gas phase growth method having a three-dimensional,tan-gled structure with a tube diameter of about8–15nm as shown in Fig.2.The small tube diameter,in fact,favors electrocata-lyst nanoparticle formation when these metal nanoparticlesareFig.2.TEM image of as-received CNT.well dispersed.In addition,the surface area is surprisingly high (233m2g−1),comparable to that of Vulcan XC72at250m2g−1, very suitable for electrode fabrication.This carbon nanotube material is considered to have several advantages over conven-tional carbon blacks.These include:(i)having more defined crystalline structure with higher conductivity,(ii)containing lit-tle impurities,such as metals and sulfides,and thus eliminating potential poisoning effects to electrocatalysts,and(iii)possess-ing three-dimensional structure and thus favoring theflow of reactant and providing a large reaction zone when fabricated into electrodes.The carbon nanotubes are also chemically stable and resistant to thermal decomposition up to more than300◦C.Due to these distinctive characteristics,this carbon nanotube material is very suitable for use as a new electrocatalyst support.A recent report by Han et al.[17]indicated that a stronger nitric acid solution generates more functional groups on CNT surfaces than a weaker one and results in better electrocatalyst formation.Therefore,a concentrated nitric acid,with addition of sulfuric acid,solution was employed in this study for oxidation. The result on generation of surface functional groups obtained from FT-IR spectroscopy is shown in Fig.3.It is clear that several types of functional groups,particularly carbonyl and hydroxyl groups,have been generated on acid-oxidized carbon nanotube surfaces as expected.In addition,it can be seen that the longer the acid treatment time,the more amounts of surface functional groups were generated as evidenced by the FT-IR spectrographs. It was reported[12]that the dominant functional group is car-boxylic group generated by strong acid treatment.High density of surface functional groups indeed ensures that high loading of electrocatalyst can be supported on CNT surfaces,which is favorable for use in DMFCs.It was found[18]that the oxidized CNT also induced a zeta potential(ζ)in a solution,such as an ethanol solu-tion,more negative than that of a pristine one due to the presences of acidic functional groups.These functional groups on oxidized CNT dissociate in the solvent and con-sequently impart negative charges on the CNT surfaces, which should be favorable for adsorption of multicharged metal complexes,such as Pt(EG)a(Cl−)b(HSO3−)c(4−b−c)+andC.-C.Chien,K.-T.Jeng/Materials Chemistry and Physics99(2006)80–8783Fig.3.FT-IR spectrographs for generation of functional groups on strong acid-oxidized CNT surfaces with different treatment time:(a)1h,(b)3h,and(c) 6h.Ru(EG)l(Cl−)m(HSO3−)n(3−m−n)+with their chloride ligands partially denuded.The accompanying large electrical repulsive forces between nanotubes prevent them from tangling and form-ing agglomeration.But,in reality the negatively charged CNT surfaces are not ideal for formation of Pt–Ru electrocatalysts in an unmodified EG solution due to different specific adsorption rates of these two metal ions and,in turn,different specific depo-sition rates between Pt and Ru.Thus,proper adjustment of the CNT surface charges using the modified EG to provide a suitable reaction condition is necessary in order to prepare Pt–Ru/CNT with excellent formation and ideal electrocatalyst composition as will be discussed later.It should also be noted that the strong acid oxidation has partially changed the surface structures of carbon nanotubes in a way of“forced corrosion.”Although this oxidative surface treatment process is helpful for generations of surface functional groups and deposition of electrocatalyst metal,it may affect the conductivity and chemical stability of the carbon nanotubes if over-treated.Thus,cares should be taken in this respect.A treat-ment time of3–6h was found to be acceptable.No obvious increases in functional groups formation on oxidized CNT sur-faces using a longer treatment time.3.2.Preparations of Pt–Ru/CNT using a modified reducing agentThe main component of the modified reducing agent is still ethylene glycol.In general,the function of EG is twofold:(a) to work as a chelating agent for complexation of metal ions in the reduction process,and(b)to serve as a reducing agent to convert metal ions into metal or alloy nanoparticles.In the preparation of Pt–Ru/CNT,the EG solution(usually contains a small amount of water)was generally adjusted to a suitable pH value,which favors formation of EG(ligand)–Pt(ion)and EG (ligand)–Ru(ion)complexes.Under this condition,the coordi-nation mechanism of ethylene glycol to metal ions is through the non-participating electron pair on oxygen and does not involve acid dissociation of alcohol groups.The formation of such com-plexes prevents too many Pt and Ru ions from sticking together. Thus,this results in the formation of small nanosized electrocata-lyst particles with uniform distribution when reduction reactions are carried out at suitable temperatures.The TEM images of Pt–Ru/CNT electrocatalysts prepared using different EG reducing agents are compared.Fig.4(a) shows the one prepared using modified EG while Fig.4(b) reveals that in more magnified details.One can clearly see that the modified EG prepared Pt–Ru/CNT has uniform particle dis-persion and small particle sizes.On the other hand,the use of unmodified EG resulted in discrete and more aggregate parti-cles as shown in Fig.4(c).By comparing with the result obtained using NaBH4as a reducing agent as shown in Fig.4(d),it can be seen that a strong reducing agent may not result in good catalyst formation on CNT.When the reducing agent is too strong,reduc-tion of metal salt or ion proceeds rapidly and the metal tends to form locally with large agglomerates.Fig.5shows the particle size distribution of Pt–Ru/CNT prepared using the modified EG. It can be seen that the particle size is,indeed,very small and nar-rowly centered at about3nm with an average of about3.3nm. This is,in fact,just about the ideal size of Pt–Ru electrocatalyst for methanol electrooxidation[19].The best reaction temperature was found to be around 110–140◦C and the reaction time was dramatically reduced from6to8h to about30min using the modified EG with microwave irradiation heating.This heating method has advan-tages over conventional conductive heating in that it is more uniform and effective.Therefore,suitable reaction tempera-tures can be reached within a much shorter time.In general, microwave irradiation heating can increase the reaction kinetics by1–2orders of magnitude over conventional heating methods within a short reaction time improving electrocatalyst nanopar-ticle formation.The metal deposition efficiency(η),i.e.the percentage of the total amount of metal ions originally exist in the reaction solution that deposit onto the CNT support surfaces, was found to be more than90%for Pt–Ru/CNT.In general,a loading of10–50wt.%Pt–Ru in a form of alloy on CNT can be readily prepared without much difference in particle size distri-bution using the modified EG in conjunction with microwave irradiation heating.In addition to particle morphology,the composition of the prepared Pt–Ru electrocatalyst is also of vital importance to have excellent electrocatalytic activity and poison-resistance in methanol electrooxidation.The effectiveness of the modified EG on forming the right electrocatalyst composition in the prepara-tion of20wt.%Pt–10wt.%Ru/CNT(Pt:Ru=1:1)was examined by the elemental analyses using EDS and ICP.Fig.6(a)shows the EDS graph of the prepared Pt–Ru/CNT using the modified EG and Fig.6(b)shows the one using unmodified EG with much more pronounced Ru signal for the paring these two graphs to that of a standard taken using the same amount of a commercial20wt.%Pt–10wt.%Ru/C electrocatalyst(Johnson Matthey)as shown in Fig.6(c),it can be seen that the use of mod-ified EG gave rise to a much better electrocatalyst composition pattern close to that of the commercial product.The intensities of EDS signals of the prepared Pt–Ru/CNT relative to those of84 C.-C.Chien,K.-T.Jeng /Materials Chemistry and Physics 99(2006)80–87Fig.4.TEM images of prepared Pt/CNT using different reducing agents:(a)modified EG,(b)modified EG (with magnified details),(c)unmodified EG,and (d)NaBH 4.the commercial standard were used to estimate the amounts of Pt and Ru deposited on CNT surfaces.It turned out that these semi-quantitative results are comparable to those obtained from the more accurate ICP tests as shown in Table 1.It can be seen that from the ICP tests the Pt–Ru/CNT electrocatalyst prepared using the modified EG has an atomic ratio (Pt:Ru)of 1:0.93very close to the ideal ratio of 1:1.On the other hand,when using unmod-ified EG,the resultant electrocatalyst is overly rich in Pt and has a poor atomic ratio of 1:0.37.Thus,the use of modified EG indeed improved the reduction reaction of ruthenium ion and,in turn,enhanced the Pt–Ru formation on acid-treated CNT.It is believed that the main contributive factor in promot-ing formation of uniform Pt–Ru nanoparticles comes fromtheFig.5.Particle size distribution of CNT-supported Pt–Ru prepared at 110◦C using the modified EG.The average size is 3.3nm.synergic effect of EG with the modification agents,i.e.NaHSO 3and Ca(OH)2.Thus,it is necessary to explore the roles of NaHSO 3and Ca(OH)2in the modified reducing agent that lead to such enhanced performances.The former is commonly employed as a reducing agent in preparation of Pt–Ru electro-catalysts [20,21]using carbon black supports with fine particle formation and therefore it was adopted into this modified polyol process to prepare Pt–Ru/CNT electrocatalysts.In addition to enhancing the reducing power of EG,SO 3is a stronger ligand than Cl.Thus,it is able to form more stable complex ions with Pt 4+and Ru 3+leading to better dispersion and,in turn,narrower nanoparticle formation.In particular,the use of NaHSO 3sub-stantially promotes the conversion efficiency of Ru 3+to Ru metal 2–3times higher than before at a lower pH value of 2–4.This is indeed a significant improvement in reductive preparation of Pt–Ru electrocatalysts supported on CNT using sulfite species as a modification agent for EG.It should be mentioned that at such low pH values the capability of EG in the complexation of metal ions becomes relatively weak.The introduction of NaHSO 3as a modification agent into the reaction solution provides a timely assistance in this respect.Thus,the dual role of NaHSO 3as a second chelating agent and as an enhancing reduction agent is of special importance.However,the pH of the deposition solution,in fact,did play a key role in the proper formation of Pt–Ru/CNT.Zhao and Gao reported [22]that the zeta potential of multi-walled car-C.-C.Chien,K.-T.Jeng/Materials Chemistry and Physics99(2006)80–8785 Table1Comparison of elemental compositions of CNT-supported Pt–Ru prepared using modified and unmodified EGReducing agent Composition measured by EDS Composition measured by ICPWeight percent a(wt.%)Atomic ratio(Pt:Ru)Weight percent(wt.%)Atomic ratio(Pt:Ru) Modified EG Pt(18.97),Ru(8.63)1:0.88Pt(19.43),Ru(9.36)1:0.93Unmodified EG Pt(9.19),Ru(1.61)1:0.34Pt(10.07),Ru(2.05)1:0.37a Calculated from the EDS signal intensities relative to those of a20wt.%Pt–10wt.%Ru/Cstandard.parison of EDS graphs:(a)Pt–Ru/CNT prepared using modified EG,(b)Pt–Ru/CNT prepared using unmodified EG,and(c)Pt–Ru/C obtained from Johnson Matthey.The use of modified EG resulted in more pronounced Ru signal and better electrocatalyst composition close to that of the commercial product.bon nanotubes in an ethanol solution is a function of the pH and increases its negative magnitude as the pH value of ethanol solution increases.They also found that the adsorption of a copolymer-based dispersant on the CNT surfaces shifts the zeta potential toward a positive direction.As the zeta potential varies from a positive to a negative value over a pH range,there exists an IEP at a specific pH.Since there is no net surface charge at the IEP,the adsorption of different ligand-complexed ions on the CNT surfaces will occur at almost the same specific rates.Thus, the composition of thefinal electrocatalyst product will depend mainly on the composition of the starting reactant,which can be readily controlled as desired.We employed this unique char-acteristic of CNT/solution interfaces and were able to make the preparation of electrocatalysts,particularly Pt–Ru,more effec-tive.Thus,the calcium hydroxide aqueous solution was used as a mild pH adjuster or a solution conditioner in conjunction with the use of NaHSO3in the modification of EG.In this case,the dispersants were the EG and NaHSO3com-plexed Pt and Ru ions.By carefully adjusted the metal deposition solution with a suitable amount of Ca(OH)2aqueous solution to a pH value of about2–4,close to where the IEP takes place and precipitation of undesired Ru salts can be avoided,a suit-able Pt–Ru deposition environment on the CNT surfaces was created.This naturally resulted in significantly improved elec-trocatalyst formation.The use of a dilute NaOH aqueous solution to adjust the pH was also found to bring about similar results in electrocatalyst deposition.From the composition of the pre-pared Pt–Ru/CNT as shown in Table1,it evidences that the deposition of different metals on CNT can be properly regu-lated to almost the same specific rates using the modified EG. It also indicates that the pH value where the IEP occurs with adsorption of ligand-complexed Pt and Ru ions on CNT is close to2–4.Thus,with the novel concept of having competitive spe-cific adsorption rates of different complexed metal ions around the IEP,the modified EG is also expected to be applicable to preparations of a variety of multi-component electrocatalysts, e.g.Pt–Ru–Ir,Pt–Ru–Rh,Pt–Ru–Ir–Rh,etc.,with desired com-positions,which will have enhanced electrocatalytic activities and poisoning resistances for fuel cell applications.Using the modified reducing agent,the metal deposition effi-ciency for Pt–Ru/CNT was significantly improved from about 40to>90%.A loading of10–50wt.%Pt–Ru on CNT with an atomic ratio of close to1:1can be readily obtained.Finally, it should be mentioned that the introduction of water into the modified EG reducing agent through the addition of aqueous solutions of NaHSO3and Ca(OH)2also affected the formation of electrocatalysts.In an earlier study,Zhou et al.[8]found that the amount of water added to EG significantly affects the par-ticle sizes of CNT-supported electrocatalysts.Li et al.[4]also reported that the higher water content in EG,the larger Pt particle size on CNT.The presence of water in EG may favor the forma-tion of complex salts and buffer the Pt–Ru particle formation in a slower rate.Its existence in the EG solution is also helpful for pH adjustment.Therefore,water should be used as an integral part of the additive for the modified EG reducing agent.How-ever,the water content in the modified reducing agent should be properly controlled so as to obtain the best performance and prevent the catalyst particles from aggregation.In this study, a water content of1–2vol.%seemed to give quite satisfactory results with small particle formations.3.3.Electrocatalytic activity of prepared Pt–Ru/CNT on methanol electrooxidationIt is interesting to know if the prepared Pt–Ru/CNT exhibits better performance with respect to methanol electrooxidation as another evidence for better electrocatalyst formation using the modified reducing agent.Fig.7illustrates the methanol elec-trooxidation currents obtained from cyclic voltammograms with。

Unit 2 第2课时 Reading（2）& grammar and usage（分层练习）20232024学年高二英语上册同步精品课堂（译林版）（解析版）基础练一、根据汉语意思填写单词二、用单词的适当形式完成句子三、根据汉语完成句子11．No two leaves from the same tree are (相同的) .同一棵树上没有两片完全相同的树叶。

12．得知你已被任命为学生会主席，我真诚地祝贺你。

Learning that the Student Association，I sincerely congratulate you.13．我希望在未来的几年里他会反思他的决定。

I hope in years to e he will .14．宴会正在准备时，这时外面下起了雪。

The feast when it began to snow outside.15．他们离婚前，就爆发了几次剧烈的争吵。

Several violent quarrels before they got divorced.提升练四、选用适当的单词或短语补全句子拓展练五、完形填空Recently, I have begun to do rides with a group of guys who ride professionally．The first day, I finished thechanged in about a minute．After we started riding again, I noticed something 31 ．The guy at the front would ride 32 for a couple of minutes, then he would move over to the side, 33 his way to the end of the line, and the guy behind him would move into the lead position．The process would 34 every few minutes．It was a lot easier than riding alone to catch up with the first rider．This time I had a great time and I think it is the fastest I've ever 35 ．This made me realize how important teamwork is, and the 36 of having a great team．There's no need to worry about your falling behind others．The entire team 37 , and so do you．You get your time to shine, and so does everyone else．You cannot get anywhereor even make any worthwhile improvementwithout a 38 ．Who else will stop and help you to change your flat tire? 24．A．caution B．envy C．ease D．difficulty25．A．annoyance B．delight C．admiration D．surprise26．A．adjusted B．found C．missed D．measured27．A．instead B．therefore C．otherwise D．still28．A．route B．direction C．side D．queue29．A．cut in B．got through C．turned up D．ran out30．A．battery B．stomach C．shoes D．tire31．A．illegal B．reliable C．unusual D．absurd32．A．quickly B．slowly C．immediately D．hesitantly33．A．giving B．making C．losing D．keeping34．A．change B．respond C．repeat D．adapt35．A．gone B．walked C．conducted D．flown36．A．pleasure B．profit C．intention D．value37．A．conflicts B．improves C．approves D．increases38．A．leader B．practice C．team D．ride六、阅读理解In January, 2021, the icemaking work on the ”Ice Ribbon“, a landmark venue for the Beijing Winter Olympics, was pleted.In the Winter Olympics, where races can be won or lost by a small time gap, tiny imperfections in the ice can make all the differences. ”It’s not just a hunk of ice like you’d normally think of, like ice cubes sitting in yourfreezer,“ told Kenneth Golden, a U. S. mathematician who studies the structures of ice. ”It’s a much more fascinating and plex substance than people would normally think.“The first step for building any ice rink is to purify the water to remove dissolved solids like salts and minerals. Such impurities don’t fit in the regular hexagonal(六边形的)structure of ice that forms as water freezes. The purer the water, the more consistent the ice surface.In addition to the need for excellence in the raw materials of icemaking, technology is also very important, As one of the most advanced technologies for winter sports venues, a carbon dioxide cooling technology has been applied on a large scale for the Beijing Winter Olympic Games. CO2 , is not new when it es to icemaking. However, it has been gradually replaced by the manmade refrigerant, like Freon.With increasing attention toward climate change, the old refrigerant has e into use again. As an element of the atmosphere, CO2, doesn’t damage the ozone layer. Although CO2 is a greenhouse gas, its greenhouse effect is much lower than that of other synthetic refrigerants. The Winter Olympics venues adopted CO2instead of Freon as a refrigerant in icemaking, which will reduce carbon dioxide emissions greatly.”We believe these technological innovations will bring Beijing 2022 to spectators all over the world in a more impressive way.“ told Gao Bo from the Media Operations Department of the Beijing Organizing mittee for the 2022 Olympic and Paralympic Winter Games.39．What is the result of impurities in water for icemaking?A．The water isn’t able to freeze pletely.B．The quality of the ice will be affected.C．The ice surface will be more consistent.D．It’s likely for athletes to fall on the ice.40．Why has CO2 cooling technology been applied for the Winter Olympic Games?A．It’s the most advanced technology for icemaking.B．CO2 is more efficient than other refrigerants.C．CO2 is more environmentally friendly than Freon.D．CO2 has already existed in the atmosphere.41．What is Gao Bo’s attitude to CO2 being applied to icemaking?A．Unclear.B．Opposed.C．Doubtful.D．Favorable.42．Which of the following is a suitable title for the text?A．The Beijing Winter Olympic Games Are ing B．Beneath Olympic IceC．The Use of Refrigerants in Olympic Games D．The Structure of Ice。

大理“PEP”2024年11版小学英语第二单元寒假试卷[含答案]考试时间：90分钟（总分:110）A卷考试人：_________题号一二三四五总分得分一、综合题(共计100题共100分)1. 选择题：单项选择。

（）1. This _ my pencil box. A ruler and a crayon_ in it A. Is, is B. are , is is,se()2.--Look at the picture of my -Wow,your bed is so beautiful. A. bedroom B. classroom C. living room()3-_are his glasses? --They're on the desk. A. What B. How C. Where（）4. The room has a big TV. The TV is on the wall. Two sofas are in the room. A table is near the sofas. A phone is on the table. You can watch TV here.()5. Look at the room. It has many books. A big desk is in it,too. A computer, a book and a pencil box are on the desk. You can read a book here.2. 填空题：I like to help my mom ________ (准备食物).3. 听力题：A molecule that consists of a carbon backbone is called a ______.4. 选择题：What do we call the process of turning grapes into wine?A. DistillationB. FermentationC. PasteurizationD. Dehydration答案: BCarbon dioxide is produced during _______ respiration.6. 填空题：I love to watch ______ (动画片) that are funny and entertaining.7. 选择题：Which animal is known for its wisdom?A. FoxB. OwlC. CrowD. Parrot答案:B8. 填空题：The capital of Ireland is _____.9. 填空题：My dad encourages me to be __________ (积极向上).10. 听力题：The __________ is a famous area known for its vineyards.11. 选择题：What is the capital of Malawi?A. LilongweB. BlantyreC. MzuzuD. Zomba答案:A12. 选择题：Which of these is a fruit?A. CarrotB. BroccoliC. AppleD. Potato13. 选择题：What do you call the study of the Earth?A. GeographyB. GeologyC. EcologyD. Meteorology答案: BIn which country is the Eiffel Tower located?A. ItalyB. GermanyC. FranceD. Spain15. Wall of __________ (中国) was built to protect against invasions. 填空题：The Grea16. 选择题：What is the sound a dog makes?A. MeowB. RoarC. BarkD. Chirp答案: C17. 选择题：How many planets are in our solar system?a. Eightb. Ninec. Tend. Eleven答案:A18. 填空题：We can build a ________ out of sticks.19. 填空题：A butterfly's life begins as an ________________ (卵).20. 选择题：What is the name of the river that runs through Egypt?A. AmazonB. NileC. MississippiD. Yangtze答案:B21. 填空题：Learning about plants can inspire ______ (环保) efforts.22. 选择题：What do you call a person who studies history?A. HistorianB. ScientistC. GeographerD. Mathematician23. 听力题：A _______ is a mixture made of two or more liquids that do not mix.24. 选择题：What do we call a young female kangaroo?A. JoeyB. CalfC. KitD. Lamb答案：A25. 听力题：I like to ___ (listen/sing) to songs.26. 听力题：Parrots can ______ human speech.27. 选择题：How many rings does Saturn have?A. 1B. 3C. 7D. 928. 填空题：I love to _______ (旅行) during holidays.29. 听力题：The boiling point of a substance is the temperature at which it ______.30. 听力题：A saturated solution will not dissolve ______.31. 听力题：The chemical formula for sodium oxalate is __________.32. 听力题：My brother likes to ride his ____ (skateboard) in the park.33. 填空题：I enjoy going to the ________ (游乐场) during summer.A turtle can breathe through its ______ (鼻子).35. 选择题：Which fruit is known for having seeds on the outside?A. KiwiB. StrawberryC. BlueberryD. Pineapple答案:B36. 听力题：A saturated solution cannot dissolve any more ______.37. 选择题：What is the main language spoken in the USA?A. SpanishB. FrenchC. EnglishD. German38. 听力题：The main gas that causes global warming is ______.39. 听力题：The cat sleeps on a _____.40. 填空题：A _____ (水果) tree takes years to mature.41. 选择题：What is the term for a baby kangaroo?A. CubB. KitC. JoeyD. Calf答案: C42. 听力题：My brother is in ________ grade.43. 听力题：The __________ is a famous lake in North America.44. 填空题：My pet bird loves to take a ______ (洗澡).What do you call a young female goose?A. GoslingB. GosseC. HenD. Duckling答案: A46. 选择题：What is the opposite of soft?A. HardB. SmoothC. RoughD. Solid47. 选择题：What do we call the process of growing crops?A. HarvestingB. PlantingC. AgricultureD. Farming答案: C48. 听力题：We have a _____ (聚会) for New Year.49. 选择题：What do we call the hard outer covering of an egg?A. ShellB. YolkC. WhiteD. Albumen答案: A. Shell50. 填空题：My brother is a __________ (策划师).51. 听力题：He is ________ (smart) in math.52. 选择题：What is the capital of Cuba?A. HavanaB. SantiagoC. TrinidadD. CamagueyA __________ (反应过程) is the series of steps in a chemical reaction.54. 填空题：The ancient city of __________ (雅典) is known for its democracy.55. 填空题：In science class, we conducted an experiment to see how plants ______ (反应) to sunlight. It was very interesting!56. 填空题：My dad helps me fix my ____.57. 填空题：The ______ (老虎) is a powerful predator.58. 听力题：The dog is ___ at the door. (barking)59. 听力题：The chemical formula for potassium permanganate is _______.60. 填空题：I planted some ______ (种子) in my garden. I hope they grow into beautiful ______ (花).61. 填空题：My dad enjoys playing with ____.62. 选择题：What do we call the process of breaking down food in the body?A. DigestionB. AbsorptionC. AssimilationD. Ingestion答案: A63. 选择题：What do we call the process of a plant making its own food using sunlight?A. PhotosynthesisB. RespirationC. DigestionD. Fermentation答案: AHow many eyes does a bee have?A. 2B. 4C. 5D. 6答案: C65. 选择题：What is 40 ÷ 5?a. 6b. 7c. 8d. 9答案:c66. 听力题：The ______ helps fish to swim.67. 填空题：I like to watch my ________ (玩具名称) dance.68. 选择题：What do we call a young llama?A. CalfB. KidC. FoalD. Pup答案:A. Calf69. 填空题：The weather is _______ (很适合户外活动)。

Highpowerelectro...High power electrochemical capacitors based on carbon nanotube electrodesChunming Niu,a)Enid K.Sichel,Robert Hoch,David Moy,and Howard TennentHyperion Catalysis International,Inc.,Cambridge,Massachusetts02138Received21November1996;accepted for publication13January1997Carbon nanotube sheet electrodes have been prepared from catalytically grown carbon nanotubes ofhigh purity and narrow diameter distribution,centered around80?.Our study shows that theelectrodes are free-standing mats of entangled nanotubes with an open porous structure almostimpossible to obtain with activated carbon or carbon?ber.These properties are highly desirable forhigh power and long cycle life electrochemical capacitors.Speci?c capacitances of102and49F/gwere measured at1and100Hz,respectively,on a single cell device with38wt%H2SO4as theelectrolyte.The same cell had a power density of?8000W/kg.?1997American Institute ofPhysics.?S0003-6951?97?03011-8?Since the discovery of arc-grown carbon nanotubes,1 there has been considerable experimental and theoretical at-tention to their properties2–5and potential applications.6–10 To date,the arc-growth method has not yielded large quan-tities of nanotubes uncontaminated by other forms of carbon. Thus,the development of applications which require bulk quantities of nanotubes have not been possible.An alterna-tive method is catalytic decomposition of hydrocarbons.11,12 The catalytically grown nanotubes with their entangled struc-ture are ideal templates or scaffolding for the synthesis of new nanostructured materials.In previous work,13we pre-pared bulk quantities of high purity SiC nano?brils from a starting material of our catalytically grown carbon nano-tubes.Others14,15have reported that carbide nanorods can be prepared using catalytically grown carbon nanotubes as a precursor.In this letter,we report on the preparation of car-bon nanotube sheet electrodes and their performance as ac-tive materials in electrochemical capacitors.Electrochemical capacitors16–19?also called supercapaci-tors and ultracapacitors?are attractive for their potentially high power and long cycle life(?10000).Recent efforts have been focused on the development of electrochemical capacitors that have high power density and improved fre-quency response.The key factors determining the power and frequency response of an electrochemical capacitor are the resistivity of the electrode materials and the resistivity of the electrolyte within the porous structure of the electrode.Car-bon in its various forms has been the most widely studied electrode material for electrochemical capacitors.Unfortu-nately,available high surface area carbons,such as activated carbon and carbon?ber,al-ways have a wide pore size dis-tribution ranging from micropores(?20??to macropores (?500??.Most of the surface area resides in micropores which are incapable of supporting an electrical double layer. The remaining surface area can be accessed as the ions mi-grate into the pores,accompanied by an increasing electro-lyte resistance.Hence,the energy stored can be withdrawn only at low frequencies or by dc.We report here a carbon nanotube electrode that has a narrow distribution of pore sizes,highly accessible surface area,low resistivity,and high stability.The catalytically grown carbon nanotubes11,12used in this work were produced commercially by Hyperion Cataly-sis International?trade name:Graphite Fibrils??.Transmis-sion electron microscopy?TEM?revealed that the carbon nanotubes have a morphology very similar to arc-grown buckytubes,i.e.,a hollow core and multiple layers of gra-phitic carbon arranged concentrically around the tube axis. The diameters of the nanotubes are remarkably uniform with an average of?80??Fig.1? a??.More signi?cantly,the nanotubes are uncontaminated by other forms of carbon or other residues except for small amounts of catalyst residue that can be easily removed.Scanning electron microscopy ?SEM?revealed that the carbon nanotubes are formed as bundles?Fig.1?b??with individual nanotubes arranged semi-parallel to each other.The diameter of the bundles is?2?m with length of?20?m.Steps involved in the preparation of carbon nanotube sheet electrodes include:?1?disassemble the nanotube aggre-gates and introduce chemical functional groups on the sur-face of the nanotubes;?2?disperse the functionalized hydro-philic nanotubes in water;?3?reassemble the individualized carbon nanotubes into an interconnected,entangled,free-standing structure.Chemical modi?cation of activated car-bons and carbon?bers is a well-studied subject.There are several methods of introducing oxygenate groups onto the surface of carbon.20–22In this study,we treated as-prepared carbon nanotubes with nitric acid,followed by?ltration, washing,and drying to yield the functionalized nanotubes. We found that the nitric acid treatment very effectively dis-assembled nanotube aggregates.As revealed by XPS analy-sis,about10%of the surfacecarbons were bound to oxygen. The functional groups introduced on the surface include:–COOH,–OH,and?C?O.Ash analysis indicated that more than90%of the catalyst residue was removed by nitric acid treatment.To prepare the nanotube electrodes,0.2g of functionalized carbon nanotubes were dispersed in200cc water,followed by?ltration,yielding a carbon nanotube sheet with diameter3.5in.After drying and thermally cross linking,a rigid carbon nanotube electrode was formed.The thickness of the electrode was?0.001in.It is important to note that the functionalized carbon nanotubes are self-a?Author to whom correspondence should be addressed.Electronic mail:hci1@/doc/bb270e09dd36a32d737581c4.htmladhesive;therefore,the solid sheet electrodes can be madewithout using binding materials which always bring impuri-ties into the structure and can degrade capacitor perfor-mance.The electrodes have smooth surfaces,uniform thick-nesses,and acceptable mechanical strength.They are ?exibleand can be easily bent,rolled,and cut to different shapes andsizes.They have shown consistent properties from batch tobatch.The measured density of the electrode is 0.8g/cc.Wefound that the density of our electrodes can be controlled byvarying the conditions of the nitric acid oxidation.Figure 2shows a SEM micrograph of a nanotube elec-trode.The electrode consists of randomly entangled andcross-linked carbon nanotubes which have diameters of80.Because of this unique architecture,we have real-ized several properties which are unobtainable with othercarbon materials.These are:a pore structure determined bythe open space between entangled ?brils,high accessible sur-face area,controllable electrode density,and high thermaland chemical stability.Unlike other types of carbon elec-trodes which contain micropores,slit pores,and dead end pores,the pores in the nanotube electrode ?Fig.2?are spaces in the entangled nanotube network,thus they are all con-nected.A pore size distribution analysis of particles made by grinding up a thick mat revealed that the nanotube electrodes are essentially free of micropores.Total pore volume is 0.79cc/g.The micropore (?20??volume is a negligible 0.0016cc/g.The average pore diameter is 92?,which is 12?larger than the average diameter of our nanotubes.The BET surface area of as-produced nanotubes is ?250m 2/g.The surface area of our nanotube electrodes is 430m 2/g.The increase is due to the nitric acid oxidation of the nanotube surfaces.Since the measured micropore volume is negligible,the surface area of the nanotube electrode resides in volumes and crevices greater than 20? in size;thus,accessible to the electrolyte.16–19In contrast,in an activated carbon with a surface area of ?1000m 2/g,less than 1/3of the surface area is available for the formation of an ionic double layer.A single-cell test device was fabricated with two carbon nanotube electrodes having diameters of 0.5in.,thickness of 0.001in.,and separated by a 0.001in.thick polymer sepa-rator ?Celgard ?using 38wt %H 2SO 4as the electrolyte.The resistivity of the electrode sheets was measured using the van der Pauw method.It was 1.6?10?2?cm.The speci?c ca-pacitance measured for this cell by a dc constant current charging method was 104F/g.The equivalent series resis-tance for this cell was 0.094?.Figure 3?a ?shows a complex-plane plot of the impedance of this capacitor.The measurements were made at a dc bias of 0V with a 10mV amplitude sinusoidal signal using a Solartron model 1250frequency response analyzer driving an EG&G PAR model 273potentiostat/galvanostat.The impedance curve intersects the real axis at a 45°angle,which is consistent with the porous nature of the electrodes when saturated with electro-lyte.Note that the frequency ‘‘knee’’in the plot is about 100Hz,which suggests that most of its stored energy is acces-sible at frequencies below 100Hz.This is unprecedented for this type of device.In comparison,the highest reported knee frequency in other capacitors is 6Hz.23The kneefrequency FIG.1.?a ?TEM micrograph of highly dispersed catalytically grown carbonnanotubes.The average diameter is ?80?;and ?b ?SEM micrograph ofas-made catalytically grown carbon nanotubes.The carbon nanotubes areformed as bundles with individual nanotubes arranged semiparallel to eachother.The diameter of the bundles is ?2?m with length of ?20?m.FIG.2.SEM micrograph of a nanotube electrode.The electrode consists ofrandomly entangled and cross-linked carbon nanotubes which have uniformdiameters of ?80?.for most commercially available electrochemical capacitors,including those specially designed for high power applica-tions,is ?1Hz.23Figure 3?b ?shows a Bode angle plot.For frequencies up to 1Hz,the phase angle is very close to ?90°,which suggests that the device functions like an ideal capacitor.The dependence of the speci?c capacitance on fre-quency is summarized in Table I.Note that the speci?c ca-pacitances are as high as 102and 49F/g at frequencies of 1and100Hz,respectively.A better frequency response means a better power performance.Figure 4shows a Ragone plot of the cell.The results were obtained using constant current discharges,?rst from 1.0to 0.5V,then from 1to 0V.The power plotted in the ?gure is the average power over the 0.5or 1V window.The data were based on the cell weight ?including two electrodes,separator,electrolyte and current collector ?.They indicate that a power density of ?8K W/kg is easily obtainable with our nanotube electrodes.The authors thank Dr.John Miller of JME,Inc.,Shaker Heights,OH for the impedance analysis and for many useful discussions,and Y.-Z.Lu of Harvard University for his as-sistance in electron microscopic work.This work has been supported by BMDO under Contract No.DASG60-96-C-0129.1S.Iijima,Nature ?London ?354,56?1991?.2J.-P.Lu,Phys.Rev.Lett.74,1123?1995?.3S.-N.Song,X.-K.Wang,R.P.H.Chang,and J.B.Ketterson,Phys.Rev.Lett.72,697?1994?.4H.-J.Dai,E.W.Wang,and C.M.Lieber,Science 272,523?1996?.5M.M.J.Treacy,T.W.Ebbesen,and J.M.Gibson,Nature ?London ?381,678?1996?.6W.A.De.Heer,A.Chatelain,andD.Ugarte,Science 270,1179?1995?.7J.M.Planeix,N.Coustel,B.Cog,V.Brotons,P.S.Kumbhar,R.Dutartre,P.Geneste,P.Bernier,andP.M.Ajayan,J.Am.Chem.Soc.116,7935?1994?.8P.M.Ajayan and S.Iijima,Nature ?London ?361,333?1993?.9A.G.Rinzler,J.H.Hafner,P.Nikolaev,L.Lou,S.G.Kim,D.Tomanek,P.Nordlander,D.C.Colbert,and R.E.Smalley,Science 269,1550?1995?.10P.M.Ajayan,O.Stephan,C.Colliex,and D.Truth,Science 265,1212?1994?.11H.G.Tennent,U.S.Patent No.4,663,230?1987?.12C.E.Snyder,H.W.Mandeville,and H.G.Tennent,International Patent WO 89/07163?1989?.13C.-M.Niu and D.Moy,Mater.Res.Soc.Symp.Proc.410,179?1996?.14H.-J.Dai,E.W.Wong,Y.-Z.Lu,S.Fan,and C.M.Lieber,Nature ?London 375,7691995.15C.M.Lieber,E.W.Wong,H.-J.Dai,B.W.Maynor,and L.D.Burns,Mater.Res.Soc.Symp.Proc.410,103 1996?.16E.Conway,in Symposium Proceedings on New Sealed Rechargeable Bat-teries and Supercapacitors ,edited by B.M.Barnett,E.Dowgiallo,G.Halpert,Y.Matsuda,and Z.Takehara ?The Electrochemical Society,Pen-nington,NJ,1993?,p.15.17R.A.Huggins,Philos.Trans.R.Soc.London,Ser.A 354,1555?1996?.18S.T.Mayer,R.W.Pekala,and J.L.Kaschmitter,J.Electrochem.Soc.140,446?1993?.19F.Burke and T.C.Murphy,Mater.Res.Soc.Symp.Proc.393,375? 1995?.20H.P.Boehm,Carbon 32,759?1994?.21T.Nakajima and Y.Matsuo,Carbon 32,469?1994?.22K.Esumi,M.Ishigami,A.Nakajima,K.Sawada,and H.Honda,Carbon 34,279?1996?/doc/bb270e09dd36a32d737581c4.html ler,in ECS Symposium Proceedings,edited by F.Delnick and M.Tomkiewicz,p.246,1996.TABLE I.Speci?c capacitance dependence on frequency.fHzC ?F/g ?0.0011130.0101100.1001081.00010210.0081100.0491000.013FIG.3.?a ?Complex-plane impedance;and ?b ?Bode angle plot of a single cell capacitor fabricated with carbon nanotube sheetelectrodes.FIG.4.Ragone plot of a single cell capacitor.It is based on the cell weight.The power is average power over the 0.5or 1V window.。