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1 Thin Soli Films 544 (2013) Contnts lists vill t SinDirt Thin Soli Films journl hompg: Mn(OH) 2 /multi-wll ron nnotu omposit thin ilms prpr y spry oting or lxil suprpitiv vis Jiun-Shing Liu,YiHu,, To-Ling Chung, Chin-Lung Hung Dprtmnt o Mtrils Enginring, Ttung Univrsity, 40 Zhongshn North Ro, 3r Stion, Tipi 104, Tiwn, ROC Mtl Inustris Rsrh n Dvlopmnt Cntr, Kohsiung, 1001 Konn Highwy, Kohsiung 81160, Tiwn, ROC rtil ino strt Avill onlin 9 April 2013 Kywors: Mngns hyroxi Multi-wll ron nnotus (MWCNTs) Nnoomposit Suprpitor Mn(OH) 2 /multi-wll ron nnotu (MWCNT) omposit thin ilms wr otin y spry oting on lxil inium tin oxi/polythyln trphthlt sustrt. Th prursors or thin ilm position wr prpr y ompltly mixing MWCNTs n KMnO 4 in ioniz wtr. Th morphologil hrtristis o th ilms wr xmin y il mission snning ltroni mirosopy n trnsmission ltron mirosopy. Phs volution o th thin ilms ws hrtriz y X-ry irtion n X-ry photoltron sptrosopy. As rsult o th position pross, Mn(OH) 2 i not only ovr th sur o MWCNTs uniormly ut lso m in MWCNTs. Th pitiv proprtis o th thin ilms wr invstigt y ltrohmil msurmnts n th pitn inrs s th wight rtio o KMnO 4 /MWCNTs inrs up to 1.6. Th highst spii pitn otin t sn rt o 20 mv s 1 ws F/g or th omposit thin ilm with th wight rtio o KMnO 4 /MWCNTs o Elsvir B.V. All rights rsrv. 1. Introution 2. Exprimntl tils Mngns oxis r wily us in nrgy storg vis u to low ost, high nrgy nsity, nvironmnt pollution r n nturl unn [1 3]. Mngns oxis hv n wily invstigt, inluing thir nnorystllin n morphous phss [4 6]. Mngns ioxi (MnO 2 ) is th min phs to hv goo storg hvior. Mny rsrhrs hv m signiint progrsss in th rition o in MnO 2 powrs with lrg sur r [7 9]. ThinMnO 2 ilms or suprpitiv ltros rportly xhiit high spii pitn o 700 F/g [10,11]. Howvr, th spii pitn o MnO 2 thin ilm rss with inrsing ilm thiknss u to th poor onutivity o MnO 2 ( Sm 1 ) n limits th hrg/ishrg rt or high-powr pplitions [12]. On th othr hn, mny orts hv n m to improv th ltroni onutivity y riting omposit mtrils using ron nnotus n othr onutiv itivs [13 15]. Du to thir xllnt ltril onutivity n high spii sur r, ron nnotus r now intnsivly us with MnO 2 to mk nnoomposits [16 20]. Suh nnoomposit ltros hv n rit using hmil vpor position thnology [18] or ltroposition [19] to posit th mngns oxis on th sur o th ron nnotus. In this stuy, multi-wll ron nnotus (MWCNTs) wr us to mk nnoomposits to improv th onutivity o mngns oxi ilms y spry oting thnology. Corrsponing uthor. Tl.: ; x: E-mil rss: huyi@ttu.u.tw (Y. Hu). Th MWCNTs prpr y hmil vpor position r rom Hnwh Nnoth Corp. In this stuy, MWCNTs wr immrs in th 3 M (HNO 3 +H 2 SO 4 ) solution n ultrsonilly virt or 5 h to rmov th mtl tlyst rom th MWCNTs. Th solution ws urthr stirr or 24 h without ultrsoni virtion. Atr stirring, th MWCNTs wr wsh with ioniz wtr until th ph vlu o solution rh 7 n ri in n ovn t 100 C or 24 h. Atr rying, g MWCNTs wr into 20 ml ioniz wtr n ultrsonilly virt to uniormly isprs in wtr. Thn potssium prmngnt (KMnO 4 ) ws into th solution with irnt wight rtio o KMnO 4 /MWCNTs n th solution ws ompltly mix y plntry ntriugl mixr or 10 min (rvolution sp is 900 rpm, rottion sp is 675 rpm). Susquntly, th prursors wr ultrsonilly virt or 2 h n thn wr pl in room tmprtur or 24 h. Th thin ilms wr otin y spry oting th solution on inium tin oxi/polythyln trphthlt (ITO/PET) sustrt with r o 1 1 m 2.Thsilms wr ri in th ovn t 60 C or 48 h n thn wr sok into ioniz wtr or 24 h to rmov th potssium ions. Th rystllogrphi struturs o th smpls wr xmin y X-ry irtion (XRD, PANlytil X'Prt PRO MPD) in Brgg Bntno onigurtion with CuKα irrition unr 45 kv n 40 ma. Ths msurmnts wr onut rom 20 to 80 with sn rt o Th hmil omposition n oning stts o th smpls wr msur y X-ry photoltron sptrosopy (XPS, VG ESCA Sintii Tht Pro). Th prssur insi th nlytil hmr ws o th orr 10 8 P. Unmonohromt Al Kα rition /$ s ront mttr 2013 Elsvir B.V. All rights rsrv.

2 J.-S. Liu t l. / Thin Soli Films 544 (2013) V ws us t 3 kv n 6.7 μa. Th pss nrgy o th photoltron ttor ws kpt t 50 V. Th nrgy lvls wr rrn to th N1s lin t V with th nitrogn gss. Th smpls wr not sujt to ion omrmnt prior to th XPSmsurmnts.Thtkonglothtstis53 nth X-ry spot siz is 15 μm. Th morphology o th thin ilm ws invstigt using il mission snning ltroni mirosop (FESEM, Hithi 4800) oprt t 15 kv. Trnsmission Eltron Mirosopy (TEM) nlyss wr prorm using JEOL JEM- 1200EX ltron mirosop oprt t 200 kv. Th ltrohmistry hvior o th ll ws xmin y th yli voltmmtry (CV) with onvntionl thr-ltro tsting systm (Eltrohmil sttion 5000 Jihn). This msurmnt ws rri out in srt 0.1 M KNO 3 ltrolyt t room tmprtur tr stning th ltro. Th ountr ltro ws pltinum n th rrn ltro ws stnr loml rrn ltro. Th msurmnt o CV ws onut rom 0 to 1 V with sn rt o 20 mvs Rsults n isussion Fig. 1 shows th ross-stion n sur SEM imgs o th smpls with irnt wight rtios o KMnO 4 /MWCNTs. It ws oun tht ll th ilms wr porous n th MWCNTs ntngl in ntwork strutur on th ITO sustrt. Th rius o th MWCNTs is out nm. Th ilm is mor porous without ition o KMnO 4. Th intrvls or sps twn MWCNTs wr ill with nnoprtils whn KMnO 4 ws s shown in Fig. 1() n (). Th siz o ths nnoprtils r in th rng o nm. Th ovrg o th nnoprtils m mor pprnt s th wight rtio o KMnO 4 /MWCNTs inrs s shown in Fig. 1(). In ition, it ws oun tht th ilm h ttr hsion to th sustrt s KMnO 4 ws in th prursor. Th XRD pttrns o th smpls r shown in Fig. 2. Th rystllogrphy phs o th mngns oxis in th smpls ws intii s Mn(OH) 2 o hxgonl pyrohroit strutur rom th JCPDS Crs ( ). Th prtil siz o Mn(OH) 2 lult rom th Fig. 1. Typil ross stion n sur SEM imgs o MWCNT/mngns oxi thin ilms prpr with KMnO 4 /MWCNT () & () 1:0, () & () 1:0.4 n () & () 1: 0.8 wight rtios.

3 188 J.-S. Liu t l. / Thin Soli Films 544 (2013) (100) (011) (012) (111) Tl 1 Atomi rtion o th spis lssii in th smpls vrsus irnt wight rtios o KMnO 4 /MWCNTs. KMnO4/MWCNTs Funtionl group C1s 64% 61% 64.5% 57.5% 53.7% 44.5% C\OR 36% 39% 34.2% 38.5% 36.3% 48.7% COOR 0% 0% 1.3% 4% 10% 6.8% Atom rtio o Mn/C % 2.88% 4.28% 6.67% 5.93% Intnsity (r. units) rtion o h spis ws lult rom th XPS sptr tht wr list in Tl 1. It hs n rport tht th C π on o th MWCNTs woul rokn n orm C\OR on y rting with KMnO 4 [21]. Suh rkg o C π on ws lso isovr in this work. Th molr rtion o C\OR n COOR spis inrs s th mount o KMnO 4 inrs s in Tl 1. This inits tht th ormtion o C\OR n COOR ons is sri to th rkg o C π on in MWCNTs. Th rtion twn th KMnO 4,MWCNT,nwtrn xprss s ollowing qution: Two tht (gr) Fig. 2. Th XRD pttrns o MWCNT/mngns oxi thin ilms prpr with KMnO 4 /MWCNT w () 1:0, () 1:0.2, () 1:0.4, () 1: 0.8, () 1:1.2, () 1:1.6 wight rtios. ( : Mn(OH) 2 ). Dy Shrrr qution is out 31.2 nm irrsptiv to th hng o th KMnO 4 /MWCNTs wight rtio. This is in wll grmnt to th osrvtion rom SEM imgs. Fig. 3 shows th XPS sptr o th smpl vrsus th wight rtio o th KMnO 4 /MWCNTs. Th intnsity o th C\C on, whih oms rom th MWCNTs, rs pprntly s th rtio o KMnO 4 /MWCNTs inrs. Th tomi rtion o Mn/C o th smpl lult rom th pk-itting o XPS (s in th insrt igur in Fig. 3)sptrwsshown in Tl 1.Thpkst285V,285.4V,n288.9Vwrlssii s th ining nrgy o C1s, C\OR, n C\OOR, rsptivly. Th molr Intnsity (ounts/s) Intnsity(ounts/s) C1S itting C-OR Bining Enrgy (V) C-OOR Bining Enrgy (V) Fig. 3. XPS sptr o C1s with MWCNT/mngns oxi thin ilms prpr with KMnO 4 /MWCNT w () 1:0, () 1:0.2, () 1:0.4, () 1: 0.8, () 1:1.2, () 1:1.6 wight rtios. KMnO 4 þ 3H 2 O þ C π ðcntþ MnðOHÞ 2 þ KOH þ 2C π ðcntþ OH þ C π ðcntþ OOH: Th phs hng rom KMnO 4 to Mn(OH) 2 is kin o hyrolysis rtion. In ition, th strong oxiizing proprty o KMnO 4 woul us th rkg o C π on in th MWCNTs [22]. Th rkg o C π on woul urthr rt with (OH)-spis. Fig. 4 shows th TEM mirogrphs o th omposits vrsus irnt wight rtios o KMnO 4 /MWCNTs. Th lightr prtils wr intii s Mn(OH) 2 whrs th rkr prtils wr intii s MnO x n som K lmnt ws tt in th mtrix rom EDS sptrum nlysis. It ws lso oun tht th Mn(OH) 2 i not only ovr th MWCNTs ut lso m into th nnotu s point y rrows in Fig. 4() n () or smll mount o th KMnO 4, rsptivly. Th prtil siz o Mn(OH) 2 nnoprtils is out 35 nm, whih grs wll with th rsults rom XRD nlysis. Fig. 5 shows th CV urvs o th smpl ltro vrsus irnt rtios o KMnO 4 /MWCNTs onut in 0.1 M KNO 3 solution t th room tmprtur with potntil sn rt o 20 mvs 1.Thrtngulr shp n mirror-img hrtristi o th CV urv rvl n il ltril oul lyr pitn hvior or th smpl with smll mount ition o KMnO 4.ThisisttriuttothommonCVhrtristis o ron nnotus. On th othr hn, th CV urv ron with highr urrnt lvl s th mount o KMnO 4 inrs. With th wight rtio o th KMnO 4 /MWCNTs = 0.4, 0.8, 1.2, th CV urvs xhiit ro noi n thoi pks ntr t out 0.9 V n 0.75 V, rsptivly. This is sri to th psuopitn hvior o Mn(OH) 2 with tion intrltion upon oxition n tion intrltion upon rution. In ition, it is oun tht th nlos r o th CV urv, orrsponing to hrg storg pility is muh lrgr thn othrs, or th smpl with wight rtio o th KMnO 4 /MWCNTs = 1.2. Th spii pitn rom th CV urv n otin oring to th ollowing qution [23]: C sp ¼ i=smðf=gþ ð1þ whr i is th vrg thoi urrnt, s is th potntil swp rt, n m is th totl mss o ltro (inluing positiv n ngtiv ltros). Fig. 6 shows th pitn o th smpl s untion o th wight rtio o KMnO 4 /MWCNTs. Th pitn o th smpl inrs s th wight rtio o KMnO 4 /MWCNTs inrs up to 1.6 n thn th pitn o th smpl rs. Th highst spii pitn o ths smpls ws F/g or MWCNT/KMnO 4 =1.2. Th hsion o th thin ilms on th sustrt ws xmin with thstnrtptstmtho(astmd mthob).thrsults o th tst show tht th thin ilms n gt th rnk o B4, whih is

4 J.-S. Liu t l. / Thin Soli Films 544 (2013) Fig. 4. TEM imgs o MWCNT/mngns oxi thin ilms prpr with CNT/KMnO 4 () 1:0, () & () 1:0.4 n () 1:0.8 wight rtios. orrsponing to th prntg o th thin ilm strip o th sustrt lss thn 5%. Suh goo hsion hvior o th thin ilms on th ITO/ PET sustrt is though u to th hmil oning twn th symmtri OH group o Mn(OH) 2 nhyrognonoito/petsur.th Currnt Dnsity (A/g) Voltg (V) Fig. 5. Cyli voltmmtry msurmnt o th smpl s untion o MWCNT/mngns oxi thin ilms prpr with KMnO 4 /MWCNT w () 1:0, () 1:0.2, () 1:0.4, () 1: 0.8, () 1:1.2, () 1:1.6 wight rtios (sn sp = 20 mv/s, sn rng = V vs. SCE). polriz proprty o OH group o Mn(OH) 2 woul mk it sy to on on th sur o MWCNT. Furthrmor, th porous ntwork mirostrutur o MWCNTs ilitt th ss o Mn(OH) 2 on n twn th MWCNTs uring spry oting. Morovr, th porous mirostrutur o th Mn(OH) 2 /MWCNT nnoomposits ws niil or th ltrolyt ss to th tiv mtril uring tsting o th Spii Cpitn (F/g) Wight rtio o KMnO 4 /MWCNTs Fig. 6. Th spii pitn with th wight rtio o KMnO 4 /MWCNTs.

5 190 J.-S. Liu t l. / Thin Soli Films 544 (2013) nnoomposits s ltrohmil suprpitors ltros in th KNO 3 solutions. As rsult, th Mn(OH) 2 /MWCNT nnoomposits show goo pitiv hvior, with th highst spii pitn o F/g t sn rt o 20 mvs Conlusions Th rsults prsnt in this ppr init tht MWCNT-Mn(OH) 2 nnoomposits on lxil ITO/PET sustrt hv n prpr y simpl spry oting thniqus. From th XRD nlysis, th prominnt phs o mngns ompoun o th ilms ws Mn(OH) 2.Thmngns hyroxi uniormly ovrs th sur o MWCNTs n som o MWCNTs wr m with mngns ompoun s osrv rom SEM n TEM. Th pitn o th smpl inrs s th wight rtio o KMnO 4 /MWCNTs inrs up to 1.6 n thn th pitn o th smpl rs. Th MWCNTs-Mn(OH) 2 nnoomposits show goo pitiv hvior, with th highst spii pitn o F/g t sn rt o 20 mvs 1. Th hsion o th thin ilms n gt th rnk o B4 o ASTM stnr mtho. Aknowlgmnt Finnil support o this rsrh y Ntionl Sin Counil, Tiwn, ROC, unr th grnt NSC E is grtully knowlg. Rrns [1] S. Kom, A. Ogt, T. Tsuhikw, Eltrohm. Commun. 10 (2008) [2] R.N. Ry, R.G. Ry, J. Powr Sours 124 (2003) 330. [3] M. Toupin, T. Brouss, D. Blngr, Chm. Mtr. 16 (2004) [4] C.C. Hu, T.W. Tsou, Eltrohm. Commun. 4 (2002) 105. [5] E. Burout, A. L Gl L Sll, D. Guyomr, Eltrohim. At 54 (2009) [6] M.S. Wu, P.C.J. Ching, Eltrohm. Soli-Stt Ltt. 7 (2004) A123. [7] R.N. Ry, R.G. Ry, J. Powr Sours 132 (2004) 315. [8] T. Brouss, M. Toupin, R. Dugs, L. Athoul, O. Crosnir, D. Blngr, J. Eltrohm. So. 153 (2006) A2171. [9] G.X. Wng, B.L. Zhng, Z.L. Yu, M.Z. Qu, Soli Stt Ionis 176 (2005) [10] S.C. Png, M.A. Anrson, T.W. Chpmn, J. Eltrohm. So. 147 (2000) 444. [11] S.C. Png, M.A. Anrson, J. Mtr. Rs. 15 (2000) [12] X. Lng, A. Hirt, T. Fujit, M. Chn, Nt. Nnothnol. 6 (2011) 232. [13] V. Surmnin, H. Zhu, B. Wi, Eltrohm. Commun. 8 (2006) 827. [14] J. Zhou, J. Chitz, R. Li, F. Wng, X. Zhou, T.-K. Shm, X. Sun, Z. Ding, Cron 47 (2009) 829. [15] S.I.A. Rzk, A.L. Ahm, S.H.S. Zin, A.R. Boini, Sr. Mtr. 61 (2009) 592. [16] L. Dmronny, E. Rymuno-Pinro, F. Bguin, J. Powr Sours 196 (2011) 580. [17] T. Brouss, P.L. Trn, O. Crosnir, R. Dugs, P. Guillmt, Y. Sullr, Y. Zhou, F. Fvir, D. Bélngr, P. Simon, J. Powr Sours 173 (2007) 633. [18] A.L.M. Ry, M.M. Shijumon, S.R. Gow, P.M. Ajyn, J. Phys. Chm. C114 (2010) 658. [19] Y. Wng, H. Liu, X. Sun, I. Zhitomirsky, Sr. Mtr. 61 (2009) [20] S.L. Chou, J.Z. Wng, S.Y. Chw, H.K. Liu, S.X. Dou, Eltrohm. Commun. 10 (2008) [21] D.V. Kosynkin, A.L. Higginothm, A. Sinitskii, J.R. Lom, A. Dimiv, B.K. Pri, J.M. Tour, Ntur 458 (2009) 872. [22] H.Y. Chu, Q.Y. Li, L. Wng, J.F. Lu, Y. Zho, Ionis 16 (2010) 233. [23] B.E. Conwy, Eltrohmil Suprpitors Sintii Funmntls n Thnologil Applitions, Kluwr Ami/Plnum Pulishrs, 1999.