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? 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim L ichun Y ang ,*S inong W ang ,J ianjiang M ao ,D eng ,Q ingsheng G ao ,*Y i T ang ,a nd O liver G. S chmidt H ierarchical MoS 2 /Polyaniline Nanowires with Excellent

D r. L. C. Yang,[+] J. W. Deng, Prof. O. G. Schmidt Institute for Integrative Nanosciences IFW Dresden, 01069 Dresden, Germany

E -mail: m slcyang@https://www.wendangku.net/doc/822247685.html,

S . N. Wang, J. J. Mao, Prof. Y . Tang Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials Fudan University

200433 Shanghai, China

P rof. Q. S. Gao Department of Chemistry Jinan University

510632 Guangzhou, China E-mail: tqsgao@https://www.wendangku.net/doc/822247685.html,

P rof. Q. S. Gao Department of Colloid Chemistry

Max Planck Institute of Colloids and Interfaces 14424 Potsdam, Germany

E-mail: qingsheng.gao@mpikg.mpg.de

P rof. O. G. Schmidt Material Systems for Nanoelectronics Chemnitz University of Technology 09107 Chemnitz, Germany [+] C urrent address: School of Materials Science and Engineering, South China University of Technology, 510640 Guangzhou, China

D OI: 10.1002/adma.201203999 I n recent years, global warming and the energy crisis have accelerated the development of electric vehicles and hybrid elec-tric vehicles, which has put forward an ever-growing demand for lithium-ion batteries (LIBs) with even higher power density

and longer cycle life. [ 1 ] The electrochemical performances of the

electrode materials are strongly dependent on their sizes, mor-phologies, and structures; therefore, to meet the requirements, many efforts have been devoted to designing novel nanostruc-tured electrode materials. Extensive research has proved that nanomaterials can achieve higher speci? c capacity and better cyclability compared with their bulky counterparts, due to the decreased diffusion lengths, enhanced kinetics and large ionic

contact area. [ 1a , 2 ] Owing to their high surface energy, nanoparti-cles however tend to self-aggregate, which reduces the effective

contact areas among the active materials, conductive reagent,

and electrolyte. [ 3 ] So it is crucial to retain the large contact to

fully ful? ll the advantage of active nanomaterials. Recently, hier-archical structures composed of various building blocks on the nanoscale have attracted great attention as a new class of elec-trode materials, which synergistically enhance the features of both micromaterials and nanomaterials. In such structures, the nanoscale dimension of building blocks promotes the kinetics

of Li +

-ion storage due to the shortened diffusion paths, while the primary architecture at the micrometer scale effectively

avoids aggregation of the active nanomaterials and facilitates

the transport of electrons and ions. [ 2a , 3b , 4 ]

A s a typical layered transition-metal sul? de, MoS 2 has a struc-ture analogous to that of graphite, in which S–Mo–S layers are

held together by van der Waals forces. [ 5 ] Such structure facili-tates reversible Li + intercalation/extraction, which enables MoS 2 to be a good electrode material for LIBs. [ 6 ] Strongly dependent

on their morphology and size, the reversible capacity of MoS 2 is obviously improved as nanoparticles or nanosheets are inte-grated on carbonaceous templates, [ 7 ] suggesting the importance

of hierarchical architectures. However, the poor electronic/ionic conductivity between two adjacent S–Mo–S sheets still

limits their further applications. [ 8 ] Constructing uniform hybrid

structures of MoS 2 with conductive and soft polymers, e.g., polyaniline (PANI), will effectively improve the conductivity

and stability of active materials. [ 9 ] In this way, the hierarchical

structure of MoS 2 /PANI, in which MoS 2 nanosheets are evenly embedded in the PANI matrix, is believed as a signi? cant inno-vation for developing novel electrode materials with improved

electrochemical performances. [ 1a , 10 ]

I n this communication, we propose a novel strategy to fab-ricate hierarchical MoS 2 /PANI nanowires in a mild condi-tion ( ≤ 200 ° C ), as shown in S cheme 1 . Starting from the 1D precursor of Mo 3O 1

0(C 6H 8N ) 2·H 2 O (anilinium trimolybdate (ATM); Figure S1 in the Supporting Information (SI)), MoO x /PANI nanwoires are received after polymerization (Figure S2,S3 in the SI), which are then converted to MoS 2

/PANI via hydro-thermal process with thiourea. The as-obtained products evenly integrate MoS 2 ultrathin nanosheets with PANI into the pri-mary 1D architecture, resulting in the novel hierarchical and polymer-hybrid nanowires. Meanwhile, the contents of MoS 2 and PANI in nanowires can be easily tuned by adding a varied amount of additional Mo-source, i.e., Mo 7O 24

(NH 4)6·4H 2O (ammonium heptamolybdate (AHM)), during polymeriza-tion. Such nanowires of MoS 2 /PANI are expected to exhibit enhanced conductivity, and ful? ll the advantage of both nano-composites and hierarchical architectures. When evaluated as an anode material for LIBs, they show remarkably improved electrochemical performances, compared with the bare MoS 2. A series of MoS 2 /PANI nanowires are denoted as MoS 2 /PANI-I, -II, and–III, respectively, and where the molar ratio of AHM to ATM ( R AHM/ATM ) is 0, 0.43, and 0.86, respectively. F igure 1 displays the scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images of MoS 2 /PANI-I, -II, and –III. Similar hierarchical nanostructures are well observed in all these samples. As con? rmed by SEM images (Figures 1 a –c), the nanowires are 200–500 nm in

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? 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim diameter and several micrometers in length. The nanowires are composed of ultrathin nanosheets, resulting in the apparent porous surface. It is worth noticing that the 2D MoS 2building

blocks are assembled into integrative nanowires, suggesting the combined features of both 1D and 2D nanostructures. Such hierarchical nanostructure can be further validated by TEM investigation. Taking MoS 2 /PANI-II nanowires for example, the ultrathin MoS 2 nanosheets with thickness about 10 nm are well observed in a single nanowire (Figures 1 d ,e). The characteristic lattice fringe corresponding to 0.61 nm should be attributed to the (002) lattice of MoS 2 (Figure

1 e ). Meanwhile, the uniform distributions of Mo, S, C, and N elements (Figure 1 d ) in MoS

2 /PANI-II, as well as their elemental mapping (Figure S4 in the SI), indicate the homogeneous combination of MoS 2 and PANI throughout the whole nanowire.

T he formation of the hierarchical structure has been found to be associated with the growth habit of MoS 2 and the hybrid fea-tures of the 1D precursor. In the controlled experiment, MoS 2 nano? akes were produced as molybdate reacts with thiourea (Figure S5a in the SI). This con? rms the anisotropic growth of MoS 2 into 2D nanostructures due to its layered structure held

by van der Waals interactions. [ 5a , b ] Meanwhile, the precursor of MoO x /PANI nanowires provides the 1D template for achieving hierarchical MoS 2

/PANI, in which the soft and ? exible chains of PANI can buffer the volume expansion and thus preserve

the wire-like morphology during the sul? dation of MoO x to

MoS 2 . In comparison, the 1D nanostructure collapses when bare MoO 3 nanowires are used as precursor, and only irregular nano?

akes are produced (Figure S5b in the SI). T he hybrid structure of MoS 2

/PANI nanowires with tunable composition is further demonstrated. The phase of hexagonal MoS 2 (Joint Committee on Diffraction Standards (JCPDS) No.: 37-1492) is clearly presented by the X-ray diffraction (XRD) patterns of the as-obtained nanowires ( F igure 2 a ). The obvious broadening of diffraction peaks is owed to the ultrathin dimension of MoS 2 nanosheets. Meanwhile, the PANI-hybrid composition is con? rmed by FT-IR spectra. As shown in Figure 2 b , the

bands at 1575 and 1491 cm ? 1 are associated

with the stretching vibration of quinonoid (Q)

and benzenoid (B) rings, respectively. [ 11 ]The

peaks at 1291 and 1220 cm

? 1 are assigned to ν C –N in Q–B–Q and B units, and those at 1130

and 815 cm ? 1

are attributed to δ C –H in Q and B rings. Furthermore, the elemental analysis results present the tunable composition of the nanowires (Figure S6 in the SI). The MoS 2 content is 59.6% as no extra Mo-source besides Mo 3O 1

0(C 6H 8N ) 2·H 2 O nanowires is added during polymerization, and it increases to 66.7 and 80.9% when R A HM/ATM is raised to 0.43 and 0.86, respectively. The tunability of the components in MoS 2/PANI nanowires indicates the signi? cance of our synthetic method for designing electrode materials with optimal performance.

D ue to the PANI-hybrid structure and hier-archical features, our MoS 2/PANI nanowires are expected to present good performance as anode materials for LIBs. F igure 3shows the initial three consecutive cyclic voltammograms (CVs) of MoS 2 /PANI-II nanowires and MoS 2 F igure 1. T ypical SEM images of the as-obtained hierarchical a) MoS 2 /PANI-I, b) MoS 2/PANI-II, and c) MoS 2

/PANI-III nanowires. d) TEM image with elemental (Mo, S, C, and N) distribu-tion. e) HR-TEM image of a MoS 2

/PANI-II nanowire obtained at R AHM/ATM of 0.43. S cheme 1. S cheme for the fabrication of hierarchical MoS 2/PANI nanowires through facile polymerization and hydrothermal-treatment of

Mo 3O 1

0(C 6H 8N ) 2·H 2O precursor. Adv. Mater. 2013, 25, 1180–1184

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? 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim of Li 2

S into S. [ 9b

, 14 ] After the ? rst cycle, the electrode is mainly composed of Mo and S instead of the initial MoS 2.Accordingly, in the following cycles, the reduction peak at around 2.0 V is

indicative of the lithiation process of S to form Li 2S , [ 14 ] ? [ 15 ]and

the peak corresponding to the conversion reaction (1) disappears. Moreover, during the anodic sweeps in the 2nd and 3rd cycles, the peaks attributed to the Mo oxidation to MoS 2 shift positively and their intensities decrease. At the same time, the intensities of the peaks associated with the oxidation of Li 2 S into S increase with cycling. It suggests more Li 2

S decomposes, which makes the major contribution to the reversible capacity. As for the com-mercial MoS 2 microparticles, the CV pro? le (Figure 3 b ) in the ? rst cycle is similar with that of MoS 2

/PANI-II. However, the oxi-dation peaks almost disappear in the following cycles, indicating poor cyclability. It is obvious that MoS 2

/PANI-II exhibits much enhanced activity and reversibility for Li + storage.

F igure 4 a displays the discharge/charge curves in the ? rst cycle of the commercial MoS 2 microparticles and the hierar-chical MoS 2 /PANI nanowires with various MoS 2contents,measured at a current density of 100 mA/g between 0.01 and 3.0 V. For all these materials, there are two plateaus located at around 1.2 and 0.6 V on the charge curves, suggesting

microparticles. There are three cathodic peaks located at 1.13,

0.68, and 0.48 V in the ? rst cycle of MoS 2/PANI-II (Figure 3a ). The sharp peak at 1.13 V corresponds to the phase transition from trigonal prismatic to octahedral resulting from the intercalation of Li + ions. [ 6b , 9b ] Before reaching the peak at 0.48 V , a broad shoulder appears at 0.68 V , which can be attributed to the formation of a gel-like solid electrolyte interface layer caused by the electro-chemically driven electrolyte decomposition. [ 12 ]The pronounced

peak located at 0.48 V is corresponding to the decomposition of MoS 2 into Mo nanoparticles embedded in a Li 2

S matrix, which is based on the conversion reaction: MoS 2 +4Li + +4e ? →M o +2Li 2

S (1). [ 13 ] In the anodic scan, the oxidation at 1.78 V can be attrib-uted to the partial oxidation of Mo to MoS 2

, and the following distinct peak located at 2.27 V is associated with the oxidation F igure 2. a ) XRD patterns, and b) IR spectra of MoS 2 /PANI nanowires syn-thesized with various R AHM/ATM values of: (I) 0, (II) 0.43, and (III) 0.86.

F igure 3.C V curves of a) MoS 2 /PANI-II, and b) MoS 2microparticles measured in the voltage range of 0–3.0 V with a scan rate of 0.1 mV/s.

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he high capacity, excellent cycle stability, and rate capability of MoS 2/PANI nanowires could be attributed to their hybrid structure with conductive PANI and the hierarchical features. Figure 4 d shows the Nyquist plots

of MoS 2 /PANI-II nanowires and the MoS 2

microparticles. The diameter of the semi-circle at high frequencies is remarkably reduced in the plot of MoS 2 /PANI-II, compared with that of bare MoS 2 microparticles, indicating the greatly decreased charge-transfer resistance at the electrode/electrolyte interface due to the combination with conductive PANI. The enhanced conductivity facilitates the electron

and Li + ion transfer in the electrode. More-over, the MoS 2

/PANI nanowires are hierarchi-cally built up with nanosheets, which avoid the aggregation and retain small dimensions and large surface area. Such ultrathin MoS 2

nanosheets shorten the diffusion paths of Li + ions, thus improving the dynamic perform-ance of Li + storage. The large contact area between the building blocks and the electro-lyte offers more active sites for Li + insertion/

distraction, resulting in high speci? c capacity.

Also the voids between the nanosheets and the soft PANI chains in the composite accommodate the volume change, which effec-tively mitigates the stress and protects active materials from

pulverization during the discharge/charge process. Therefore, the cycling performance of the MoS 2 /PANI nanowires is greatly improved. I n summary, we have successfully developed a facile strategy to synthesize hierarchical MoS 2 /PANI nanowires from the MoO x -based organic–inorganic hybrid nanowires. The as-obtained MoS 2

/PANI nanowires are signi? cant for their hierar-chical nanostructures integrated with 2D MoS 2 building blocks, in which MoS 2

-PANI composition is well-de? ned by initial ratios of the precursors. These unique MoS 2/PANI nanowires

exhibit greatly improved Li + -storage properties owing to the hierarchical textures and the PANI-hybrid structures. MoS 2 /PANI-II nanowires with the optimal composition (MoS 266.7%:

PANI 33.1%) display a high charge capacity of 1063.9 mAh/g at a current density of 100 mA/g, retaining 90.2% of the initial reversible capacity after 50 cycles. These results clearly demon-strate the advantage of the PANI-hybrid hierarchical structures, and further point out a new protocol for developing electrode-materials based on organic–inorganic nanohybrids. E xperimental Section T he precursor of Mo 3O 1

0(C 6H 5N H 3)2·2H 2 O nanowires was prepared according to our previous reports. [ 16 ] 2.48 g of (NH 4)6M o 7O 24 · 4H 2O and 3.34 g of aniline were dissolved in 40 mL of distilled water, and then aqueous HCl (1 M) was dropwise added until white precipitate appeared (pH 4–5). After stirring at 50 ° C for 2 hours, the white product of Mo 3O 10(C 6H 5N H 3)2·2H 2 O nanowires were obtained. MoO x /PANI nanowires were prepared using i n-situ polymerization method, in which

0.34 g of Mo 3O 10(C 6H 5N H 3)2·2H 2

O nanowires and a varied amount of

(NH 4)6M o 7O 24·4H 2 O were initiated by 0.57 g of (NH 4)2S 2O 8 in 40 mL of water for 6 hours, and the pH level was adjusted to ～ 2 by HCl (1 M).

the two-step lithiation process of MoS 2

; and the other two at around 1.7 and 2.2 V during discharge correspond to the reversible Li + extraction, which is in accordance with the CV pro? les. In the ? rst cycle, the MoS 2 microparticles exhibit a charge capacity of 684.9 mAh/g, while the nanowires of MoS 2 /PANI-I, -II, and -III deliver much improved capacities of 827.5, 1062.7, and 1015.3 mAh/g, respectively. Besides higher speci? c capacity in the initial cycle, the MoS 2/PANI nanowires show better cycling performance than that of MoS 2micropar-ticles (Figure 4 b ). The reversible capacity of MoS 2microparti-cles drops to around 184.9 mAh/g after 20 cycles. In contrast, MoS 2 /PANI-I, -II, and -III retain reversible higher capacities of 474.2, 952.6, and 748.8 mAh/g after 50 cycles, respectively. Among these hybrid nanowires, MoS 2

/PANI-II with 33.1% PANI presents the highest speci? c capacity and the best cycla-bility, implying the importance of PANI content in the com-posite. PANI can improve the conductivity of the composite; however, its speci? c capacity is lower than that of MoS 2.There-fore, only with the optimal weight ratio of MoS 2 to PANI, the hybrid nanowires can exhibit the best performance. T he high reversible capacity and good cycling behavior of MoS 2

/PANI-II are also exhibited in the rate capability. Figure 4 c shows the rate capability of MoS 2 /PANI-II and commercial MoS 2 . The hierarchical nanowires of MoS 2/PANI-II deliver

a reversible capacity of 1006.4 mAh/g at a current density of 200 mA/g in the ? rst cycle, and retain a capacity of around 320 mAh/g as the current density increases to 1000 mA/g. When the current density decreases to 200 mA/g after cycling under high current densities, MoS 2

/PANI-II can still regain a reversible capacity near 900 mAh/g. As for the MoS 2micropar-ticles, the reversible capacity fades to less than 50 mAh/g as the

current density is 1000 mA/g, and regains only around 40% of the initial capacity, i.e., 250 mAh/g, when the current density drops back to 200 mA/g. F igure 4. a ) Discharge/charge curves for the initial cycle, and b) cycling performance of the MoS 2 /PANI nanowires and the commercial MoS 2

microparticles tested in the range of 0.01–3.0 V vs Li +

/Li at the current density of 100 mA/g. c) Rate performances (charge capacity is presented), and d) Nyquist plots (100 kHz–10 mHz) of MoS 2 /PANI-II nanowires and MoS 2

microparticles. Adv. Mater. 2013, 25, 1180–1184

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? 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim T he hierarchical MoO x

/PANI nanowires were synthesized using above MoO x /PANI nanowires as precursors. 0.40 g of MoO x /PANI nanowires

were dispersed in 20 mL of H 2

O containing 0.30 g of thiourea, which were then transferred to a Te? on-lined stainless-steel autoclave and treated at 200 ° C for 2 days. After that, the product was collected by centrifugation, then three times thoroughly washed with water, and ? nally dried at 50 °C .

X RD measurements were performed on a D8 Diffractometer from Bruker instruments (Cu K α radiation, λ = 0.154 nm) equipped with a scintillation counter. TEM images were taken using a JEOL JEM-2010 operated at an acceleration voltage of 200 kV. EFTEM and EDS measurements were carried out on a TEM (FEI Tecnai F-20). The samples were dispersed in ethanol by sonication and then supported onto a holey carbon ? lm on a copper grid. SEM measurement was performed on a LEO 1550 Gemini instrument. The samples were loaded on carbon coated stubs and coated by sputtering an Au/Pd alloy prior to imaging. The IR spectra were collected with a BIORAD FTS 6000 FTIR spectrometer, equipped with an attenuated total re? ection (ATR) setup. CHNS elemental analysis was done using a Vario EL Elementar. T o evaluate the electrochemical performance of the MoS 2/PANI nanowires and the commercial MoS 2 microparticles (purchased from Sigma-Aldrich), Swaglok-type cells were assembled in an Argon-? lled glove box. For preparing the working electrodes, the active material, carbon black and poly(vinylidene di? uoride) (PVDF) were mixed in a weight ratio of 80:10:10, and then suspended in N -methylpyrrolidone to make a slurry that was spread uniformly on a copper foil. The coated copper foil was cut into round pieces with a diameter of 1 cm, dried under ambient condition and then at 120 ° C in a vacuum overnight. In a two-electrode Swaglok-type cell, a dried round piece was used as the working electrode, pure lithium foil was used as the counter and reference electrode, a glass ? ber ? lter (GF/D) from Whatman was used as the separator, and a solution of 1M LiPF 6 in ethylene carbonate/dimethyl carbonate/diethyl carbonate (1:1:1) purchased from Merck Chemicals with an additive of vinylene carbonate (2 vol%) was used as the electrolyte. The cyclic voltammetry and Nyquist plots were recorded using a Zahner IM6 electrochemical work station. Galvanostatic cycling was performed using an Arbin BT2000 system in

the voltage of 0.01–3.0 V (vs Li + /Li).

S upporting Information

upporting Information is available from the Wiley Online Library or from the author.

A cknowledgements W e are grateful for the ? nancial support from the Leibniz Pakt project “Nano-structured electrochemical energy storage for autonomous microsystems”, the Max-Planck Society, NSFC (21203075) and the 973

Program (2013CB934101). L.C.Y . thanks Dr. S. Oswald, Mr. S. L. Li, and Dr. L. B. Ma from IFW Dresden for the kind help and fruitful discussions. Q.S.G. thanks Dr. X. F. Liu and Ms. K. Otte from MPIKG for the kind

help in SEM measurement.

R eceived: September 24, 2012Published online: December 11, 2012

[ 1]a ) P . G. B ruce ,B . S crosati ,J . M. T arascon ,A ngew. Chem. Int. Ed.

2008,47,2930 ;b ) K . S. K ang ,Y . S. M eng ,J . B reger ,C . P. G rey ,G . C eder ,S cience 2006,311,977 ;c ) J . B. G oodenough ,Y . K im , C hem. Mater. 2010,22,587 ;d ) M . A rmand ,J . M. T arascon ,N ature

2008,451,652 .[ 2]a ) Y . G. G uo ,J . S. H u ,L . J. W an ,A dv. Mater. 2008,20,2878 ;b ) J . C hen ,F . Y . C heng ,A ccounts Chem. Res. 2009,42,713 ;c ) H . L i ,Z . X. W ang ,L . Q. C hen ,X . J. H uang ,A dv. Mater. 2009,21,4593 .[ 3]a ) Y . S. H u ,P . A delhelm ,B . M. S marsly ,S . H ore ,M . A ntonietti ,J . M aier ,A dv. Funct. Mater. 2007,17,1873 ;b ) A . M agasinski ,P .D ixon ,B .H ertzberg ,A .K vit ,J .A yala ,G .Y ushin ,N at. Mater. 2010,

9,353 .[ 4]a ) J . S. C hen ,Y . L. T an ,C . M. L i ,Y . L. C heah ,D . Y . L uan ,S . M adhavi ,F . Y . C. B oey ,L . A. A rcher ,X . W. L ou ,J . Am. Chem. Soc. 2010,132,6124 ;b ) X . L. W ang ,W . Q. H an ,H . Y . C hen ,J . M. B ai ,T . A. T yson ,X . Q. Y u ,X . J. W ang ,X . Q. Y ang ,J . Am. Chem. Soc. 2011,133,20692 ;c ) L . Q. M ai ,F . Y ang ,Y . L. Z hao ,X . X u ,L . X u ,Y . Z. L uo , N at. Commun. 2011,2,5;d ) J . P opovic ,R . D emir-Cakan ,J . T ornow ,M . M orcrette ,D . S. S u ,R . S chlogl ,M . A ntonietti ,M . M. T itirici , S mall 2011,7,1127 .[ 5]a ) J . N. C oleman ,M . L otya ,A . O ’Neill ,S . D. B ergin ,P . J. K ing ,U . K han ,K . Y oung ,A . G aucher ,S . D e ,R . J. S mith ,I . V. S hvets ,S . K. A rora ,G . S tanton ,H . Y . K im ,K . L ee ,G . T . K im ,G . S. D uesberg ,T . H allam ,J . J. B oland ,J . J. W ang ,J . F. D onegan ,J . C. G runlan ,G . M oriarty ,A . S hmeliov ,R . J. N icholls ,J . M. P erkins ,E . M. G rieveson ,K . T heuwissen ,D . W. M cComb ,P . D. N ellist ,V . N icolosi ,S cience 2011,331,568 ;b ) H . M atte ,A . G omathi ,A . K. M anna ,D . J. L ate ,R . D atta ,S . K. P ati ,C . N. R. R ao ,A ngew. Chem. Int. Ed. 2010,49,4059 ;c ) Q . S. G ao ,C . G iordano ,M . A ntonietti , A ngew. Chem. Int. Ed. 2012,51,11740 .[ 6]a ) A . V. M urugan , M . Q uintin , M . H. D elville , G . C ampet , C . S. G opinath ,K . V ijayamohanan ,J . Power Sources 2006,156,615 ;b ) Y . M iki ,D . N akazato ,H . I kuta ,T . U chida ,M . W akihara ,J . Power Sources 1995,54,508 ;c ) C . Q. F eng ,J . M a ,H . L i ,R . Z eng ,Z . P. G uo ,H . K. L iu ,M ater. Res. Bull. 2009,44,1811 .[ 7]a ) S . J. D ing ,J . S. C hen ,X . W. L ou ,C hem.-Eur. J. 2011,17,13142 ;b ) K . C hang ,W . X. C hen ,L . M a ,H . L i ,H . L i ,F . H. H uang ,Z . D. X u ,Q . B. Z hang ,J . Y . L ee ,J . Mater. Chem. 2011,21,6251 ;c ) K . C hang ,W . X. C hen ,A CS Nano 2011,5,4720 ;d ) H . H wang ,H . K im ,J . C ho , N ano Lett. 2011,11,4826 ;e ) C . F. Z hang ,Z . Y . W ang ,Z . P. G uo ,X . W. L ou ,A CS Appl. Mater. Interfaces 2012,4,3765 .[ 8]A . B. L aursen ,S . K egnaes ,S . D ahl ,I . C horkendorff ,E nergy Environ. Sci. 2012,5,5577 .[ 9]a ) J . X iao ,D . W. C hoi ,L . C osimbescu ,P . K oech ,J . L iu ,J . P. L emmon , C hem. Mater. 2010,22,4522 ;b ) J . X iao ,X . J. W ang ,X . Q. Y ang ,S . D. X un ,G . L iu ,P . K. K oech ,J . L iu ,J . P. L emmon ,A dv. Funct. Mater. 2011,21,2840 ;c ) F . L eroux ,B . E. K oene ,L . F. N azar ,J . Electro-chem. Soc. 1996,143,L 181 ;d ) Y . G. W ang ,W . W u ,L . C heng ,P . H e ,C . X. W ang ,Y . Y . X ia ,A dv. Mater. 2008,20,2166 ;e ) R . B issessur ,P . K. Y . L iu ,S olid State Ionics 2006,177,191 .[10 ]a ) L . Q. M ai ,X . X u ,C . H. H an ,Y . Z. L uo ,L . X u ,Y . M. A. W u ,Y . L. Z hao ,N ano Lett. 2011,11,4992 ;b ) C . K. C han ,H . L. P eng ,G . L iu ,K . M cIlwrath ,X . F. Z hang ,R . A. H uggins ,Y . C ui ,N at. Nanotechnol. 2008,3,31 .[11 ]a ) Q . S. G ao ,S . N. W ang ,Y . T ang ,C . G iordano ,C hem. Commun.

2012,48,260 ;b ) S . N. W ang ,Q . S. G ao ,Y . H. Z hang ,J . G ao ,X . H. S un ,Y . T ang ,C hem.-Eur. J. 2011,17,1465 .[12 ]Q . W ang ,J . H. L i ,J . Phys. Chem. C 2007,111,1675 .[13 ]X . P. F ang ,X . Q. Y u ,S . F. L iao ,Y . F. S hi ,Y . S. H u ,Z . X. W ang ,G . D. S tucky ,L . Q. C hen ,M icroporous Mesoporous Mater. 2012,151,418 .[14 ]X . P. F ang ,X . W. G uo ,Y . M ao ,C . X. H ua ,L . Y . S hen ,Y . S. H u ,Z . X. W ang ,F . W u ,L . Q. C hen ,C hem. Asian J. 2012,7,1013 .[15]a )S .E.C heon ,K .S.K o ,J .H.C ho ,S .W.K im ,E .Y .C hin ,H .T.K im ,J . Electrochem. Soc. 2003,150,A 800 ;b ) J . L. W ang ,J . Y ang ,C . R. W an ,K . D u ,J . Y . X ie ,N . X. X u ,A dv. Funct. Mater. 2003,13,487 .[16 ]a ) Q . S. G ao ,C . X. Z hang ,S . H. X ie ,W . M. H ua ,Y . H. Z hang ,N . R en ,H . L. X u ,Y . T ang ,C hem. Mater. 2009,21,5560 ;b ) Q . S. G ao ,S . N. W ang ,H . C. F ang ,J . W. W eng ,Y . H. Z hang ,J . J. M ao ,Y . T ang , J . Mater. Chem. 2012,2

2,4709; c) Q .S. G ao ,L .C. Yang ,X . C. Lu, J. J. Mao, Y . H. Zhang, Y . P. Wu, Y . T ang, J . Mater. Chem. 2010,20,2807.

Adv. Mater. 2013, 25, 1180–1184