本文比较了由化学气相沉积法制备的不同直径(在100 nm以内)的多壁碳纳米管(CNT)的抗电化学氧化性.将CNT电极于1.2 V(vs.RHE)下电氧化120 h,记录氧化电流~时间变化曲线;X射线光电子能谱(XPS)分析氧化前后CNT的表面化学组成.结果表明,随着CNT直径的减小,其氧化电流降低,但其中以为10~20 nm的CNT电极氧化电流最小,表面氧的增量也最小,即被氧化的程度最低,抗电化学氧化性最强.根据不同直径CNT的缺陷位、不定型碳的丰度和碳原子的应力能,分析了其抗电化学氧化性差异的原因.
The resistance to electrochemical oxidation of multi-wall carbon nanotubes(CNT) with various diameters is investigated by applying a fixed potential of 1.2 V(RHE) for 120 h in 0.5 mol L~(-1) H_(2)SO_(4).The oxidation current of CNTs decreases with their diameters,but CNTs between 10~20 nm in diameter(D1020) shows the lowest oxidation current.XPS analysis shows that,after oxidation,the increase in surface oxygen for D1020 is the smallest,implying that the oxidation degree for D1020 is the lowest.The conclusion can be reached that CNTs between 10~20 nm in diameter are the most resistant to electrochemical oxidation.The difference in electrochemical stability of CNTs is attributed to the difference in CNT structure: the amount of defects and amorphous carbon and the carbon atom strain caused by the curvature.
[1]Iijim a S.Helicalm icrotubu les of graph itic carbon[J].Nature,1991,354(6348):56~58.
[2]L i N Q,W ang J X,L iM X.E lectrochem istry at carbonnanotube electrodes[J].Reviews in Analytical Chem is-try,2003,22(1):19~33.
[3]Chen J H,L iW Z,W ang D Z,et al.E lectrochem icalcharacterization of carbon nanotubes as electrode inelectrochem ical doub le-layer capac itors[J].Carbon,2002,40(8):1193~1197.
[4]Morris R S,D ixon B G,Gennett T,et al.H igh-ener-gy,rechargeab le L i-ion battery based on carbon nano-tube technology[J].Journal of Power Sources,2004,138(1~2):277~280.
[5]Tang Y W(唐亚文),Bao J C(包建春),Zhou Y M(周益明),et al.Preparation of Pt/carbon-nanotubescatalysts and the ir electrocatalytic activities for oxidationofm ethanol[J].Ch inese Journal of Inorgan ic Chem is-try(无机化学学报),2003,19(8):905~908.
[6]L iW Z,L iang C H,Q iu J S,et al.Carbon nanotubesas support for cathode catalyst of a d irect m ethanol fuelcell[J].Carbon,2002,40(5):791~794.
[7]Tang H,Chen J H,Huang Z P,et al.H igh d ispersionand electrocatalytic properties of p latinum on well-a-ligned carbon nanotube arrays[J].Carbon,2004,42(1):191~197.
[8]Yuan F L.Ryu H J.The synthesis,characterization,and perform ance of carbon nanotnbes and carbon nanofi-bres w ith controlled size and morphology as a catalystsupportm aterial for a polym er electrolyte m embrane fuelcell[J].Nanotechnology,2004,15(10):S596~S602.
[9]X ie J,W ood D L,W ayne D M,et al.Durab ility ofPEFCs at h igh hum id ity cond itions[J].Journal of theE lectrochem ical Soc iety,2005,152(1):A104~A113.
[10]Kangasn iem i K H,Cond it D A.Jarvi T D.Character-ization of vu lcan electrochem ically oxid ized under sim-u lated PEM fuel cell cond itions[J].Journal of theE lectrochem ical Soc iety,2004,151(4):E125~E132.
[11]S innott S B,Andrews R,Q ian D,et al.Model of car-bon nanotube growth through chem ical vapor deposition[J].Chem ical Physics Letters,1999,315(1~2):25~30.
[12]Lu X K,Ausm an K D,P iner R D,et al.Scann ing e-lectron m icroscopy study of carbon nanotubes heated ath igh temperatures in air[J].Journal ofApp lied Phys-ics,1999,86(1):186~189.
[13]Yao N,Lord i V,M a S X C,et al.Structure and oxi-dation patterns of carbon nanotubes[J].Journal ofM aterials Research,1998,13(9):2432~2437.
[14]Ito T,Sun L,Crooks R M.E lectrochem ical etch ing ofind ividual mu ltiwall carbon nanotubes[J].E lectro-chem ical and Solid-State Letters,2003,6(1):C4~C7.
[15]W ang C,W aje M,W ang X,et al.Proton exchangem embrane fuel cells w ith carbon nanotube based elec-trodes[J].Nano Letters,2004,4(2):345~348.
[16]Andrews R,Jacques D,Q ian D L,et al.Mu ltiwallcarbon nanotubes:Synthesis and app lication[J].Ac-counts of Chem ical Research,2002,35(12):1008~1017.
[17]Shao Y Y(邵玉艳),Y in G P(尹鸽平),Gao Y Z(高云智).E lectrochem ical surface area enhanced byd im ethyl-ether(DME)electrooxidation[J].Ch ineseJournal of Inorgan ic Chem istry(无机化学学报),2005,21(7):1060~1064.
[18]Kuo T C,M cCreery R L.Surface chem istry and elec-tron-transfer k inetics of hydrogen-mod ified glassy car-bon electrodes[J].Analytical Chem istry,1999,71:1553~1560.
[19]F igue iredo J L,Pere iraM F R,Fre itasM M A,et al.Mod ification of the surface chem istry of activated car-bons[J].Carbon,1999,37:1379~1389.
[20]Fang H T,L iu C G,Chang L,et al.Purification ofsingle-wall carbon nanotubes by electrochem ical oxida-tion[J].Chem istry of M aterials,2004,16(26):5744~5750.
[21]ChengH M(成会明).Carbon Nanotubes:Synthesis,M icrostructure,Properties and App lications(纳米碳管:制备、结构、物性及应用)[M].Be ijing:Chem icalIndustry Press,2002,181.
