-Conjugated Nickel Bisdithiolene Complex. Nanosheet

Transcription

1 Supporting Information -Conjugated Nickel Bisdithiolene Complex Nanosheet Tetsuya Kambe, Ryota Sakamoto, Ken Hoshiko, Kenji Takada, Mariko Miyachi, Ji-Heun Ryu, Sono Sasaki,, Jungeun Kim, Kazuo Nakazato, Masaki Takata,, and Hiroshi Nishihara*, Department of Chemistry, Graduate School of Science, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, Japan Department of Electrical Engineering and Computer Science, School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya , Japan. Department of Biobased Materials Science, Graduate School of Science and Technology, Kyoto Institute of Techonogy, Hashigami-cho, Matsugasaki, Sakyo-ku, Kyoto , Japan. Japan Synchrotron Radiation Research Institute / SPring-8, Kouto, Sayo-cho, Sayo-gun, Hyogo , Japan. SPring-8 Center, RIKEN, Kouto, Sayo-cho, Sayo-gun, Hyogo , Japan. nisihara@chem.s.u-tokyo.ac.jp S1

2 Contents A. Methods B. HR-TEM image and SAED of micro-1 (Figure S1) C. IR spectra of micro-1 (Figure S2) D. PXRD measurements and the simulations (Figure S3) E. XPS of micro-1 (Figure S4) F. Deconvolution of the S 2s peaks in the XPS of micro-1 and reduced micro-1 (Figure S5) G. S 2s peaks in the XPS of nickel bisdithiolene complexes (Bu 4 N) n [Ni(bdt) 2 ] (n = 0, 1, 2) (bdt = 1,2-benzenedithiolate) (Table S1) H. Electrical properties of micro-1 and reduced micro-1 (Figure S6) I. Analysis of the moiré structure of nano-1 on HOPG (Figure S7) J. XPS of nano-1 (Figure S8) K. Deconvolution of the S 2s peaks in the XPS of nano-1 and reduced nano-1 (Figure S9) L. Complete citation of reference 12 in the main text S2

3 A. Methods Materials. Ni(OAc) 2 4H 2 O was purchased from Kanto Chemical Co., Inc. NaBr was received from Wako Pure Chemical Industries, Ltd. Dichloromethane and ethyl acetate were distilled from NaH under a nitrogen atmosphere, and were stored with molecular sieves (4A, 1/16). Acetonitrile was purified with a Glass Contour Solvent Dispensing System (Nikko Hansen & Co., Ltd.). Water was purified using the Milli-Q purification system (Merck KGaA). Benzenehexathiol (BHT) 38 and NaTCNQ 39 was synthesized according to the method described previously. Substrate preparations. HOPG was purchased from Alliance Biosystems, Inc. (Grade SPI mm) and cleaved with adhesive tape just before use. Silicon wafers (P-doped with a concentration of cm 3 ) with thermally grown 100 nm-thick SiO 2 were purchased from Yamanaka Semiconductor, and cut into squares (12 12 mm). HMDS treatment was carried out in a petri dish. A silicon wafer was immersed in an ethanol solution (10 ml) of HMDS (100 L) for 1 day. After annealing at 130 C for 2 min, the wafer was rinsed with ethanol and dried in vacuo. Preparation of micro-1. Under an argon atmosphere, mg of BHT was added to degassed dichloromethane (10 ml) in a glass vial with a diameter of 40 mm, to prepare a saturated solution (0.24 mm). The dichloromethane solution was then covered with degassed pure water (10 ml) to form a double layer. A degassed aqueous solution (10 ml) containing Ni(OAc) 2 (5 mm) and NaBr (1 mm) was added to the water phase. After waiting for 1 day, micro-1 emerged at the interface as a black solid with a metallic luster. After the removal of the aqueous and organic phases, micro-1 was washed thoroughly with water, ethanol, and dichloromethane, and dried in vacuo at 150 C. Preparation of reduced micro-1. Under an Ar atmosphere, micro-1 (10.0 mg, 6.8 mol of bisdithiolene moieties) and NaTCNQ(154 mg, 0.68 mmol) were added to acetonitrile (50 ml). The solution was refluxed for 15 h. Then the mixture was filtered through a membrane filter. The resultant black solid was washed with boiling acetonitrile until the filtrate became colorless. After drying at 150 C in vacuo, reduced micro-1 (black-luster solid, 9.4 mg) was obtained. S3

4 Preparation of nano-1. An ethyl acetate solution of BHT ( M) was gently sparged to the surface of an aqueous solution of Ni(OAc) 2 (50 mm) and NaBr (10 mm). The amount of BHT was restricted, so that it covered 50% of the aqueous surface area. The area covered with BHT was calculated using the space-filling model. Two hours allowed the ethyl acetate to evaporate, which resulted in the formation of nano-1 on the air water interface. nano-1 was deposited on a HOPG substrate by bringing the substrate close to the interface in the horizontal direction (Langmuir Schaefer (LS) method 40 ). nano-1 on HOPG was annealed for 8 days at 300 K. The samples for SPM measurements were prepared using BHT covering 20% of the aqueous surface. Preparation of reduced nano-1. reduced nano-1 was fabricated using an ethyl acetate solution of BHT ( M) and NaTCNQ ( M). Under an argon atmosphere, this ethyl acetate solution was spread on the surface of an aqueous solution of Ni(OAc) 2 (50 mm) and NaBr (10 mm) in the same way as the synthesis of nano-1. After 19 hours, reduced nano-1 was transferred on a HMDS/Si wafer by the LS method, followed by rinse with degassed CH 2 Cl 2. Characterization. FE-SEM images were collected using a JEOL JSM-7400FNT equipped with an EDS analyzer (JEOL EX-2300). TEM images were recorded at 75 kv using a Hitachi HF-2000 equipped with an AMT-CCD camera. The TEM samples were prepared by depositing micro-1 on a carbon film supported by a copper grid, using ethanol suspension. IR(ATR) spectra were recorded using a Jasco FT/IR-6100 at room temperature under vacuum. PXRD data were obtained using synchrotron radiation (λ = 0.50 Å) at Beamline BL02B2 at Super Photon ring-8 GeV (SPring-8) in Japan. To prepare the samples, micro-1 was ground finely in an agate mortar and packed in 0.5 mm-diameter soda tubes. XPS data were obtained using PHI 5000 VersaProbe (ULVAC-PHI, INC.). Al Kα (15 kv, 25 W) was used as the X-ray source, and the beam was focused on a 100 μm 2 area. The spectra were analyzed with MultiPak Software, and standardized using a C(1s) peak at ev. AFM and STM were carried out using an Agilent Technologies 5500 Scanning Probe Microscope, under ambient conditions. AFM was performed in the high-amplitude mode (trapping mode), with a silicon cantilever PPP-NCL (Nano World). Probes for STM (Pt-Ir alloy, 4:1, 0.25 mm ) were cut from a wire using a nipper, to obtain a sharp edge. Electrochemical measurements were recorded using ALS 750A and 650B electrochemical analyzers (BAS. Co., Ltd.). micro-1 was deposited onto a 3mm glassy carbon disk electrode (Tokai Carbon Co., Ltd). nano-1 was S4

5 deposited to an HOPG substrate with 25 depositions. These modified carbon materials were used as working electrodes. A homemade Ag + /Ag reference electrode (0.01 M AgClO 4 in 0.1 M-Bu 4 NClO 4 /acetonitrile) and a Pt wire counter electrode were integrated to establish a three-electrode system. Bu 4 NClO 4 and Bu 4 NPF 6, acting as supporting electrolytes, were recrystallized from EtOH and held under vacuum for 24 h. Ferrocene was used as an internal standard. Electrical property. Electrical conductivity data were collected using the two-electrode setup. micro-1 (6.2 mg) and reduced micro-1 (6.0 mg) were pressed with a pressure of 500 kg/cm 2 to form self-standing films. These pelletized films were placed on fluoropolymer boards, and were attached to aluminum electrodes using silver paste (Fujikura Kasei Co., Ltd), respectively. The temperature was controlled using a cryostat (Unisoku Co., Ltd). I V data were collected using an ALS 750A electrochemical analyzer. S5

6 B. HR-TEM image and SAED of micro-1 Figure S1. (a) SAED pattern of micro-1. (b) TEM image which showed the SAED pattern (scale bar: 20 nm). (c) A hexagonal two-dimensional lattice that gives the SAED pattern. S6

7 C. IR spectra of micro-1 S-H C S micro-1 Absorbance / a.u. BHT Wavenumber / cm Figure S2. IR spectra using ATR method of micro-1 (red) and BHT (blue). S7

8 D. PXRD measurements and the simulations Two crystal structures were considered using Crystalmaker 2. To simplify the modeling, the composition of the model crystals was fixed to (NiC 4 S 4 Na) n. One structure is a staggered structure with a space group of P6 3 /mmc. The cell parameters of a = b = 1.41 nm were determined by the observed diffraction peak at 2.35, assuming that it corresponded to the (100) diffraction. Na + was put in the hexagonal cavity. The c cell parameter was determined to be 0.76 nm, which indicated that the interlayer distance was 0.38 nm. The diffractions (110) and (300) matched the observed data. The diffractions (111), (200), (210), and (001) were either forbidden or quasi-forbidden. We assigned the observed broad peaks to the (101) and (201) planes: we suppose the stacking of the nanosheet is likely to disorder compared to the in-plane periodicity. Another possibility of the crystal lattice is an eclipsed structure with a space group of P6/mmm (Figure S3b). However, the intensity of the simulated diffraction peaks did not match the observed data. Figure S3. (a) PXRD pattern (red). Simulating plots were calculated using staggered (black) and eclipsed (blue) patterns with a = b = 1.41 nm. The c cell parameter is 0.76 nm for the staggered pattern, and 0.38 nm for the eclipsed pattern. (b) Model structures of the staggered pattern (upper) and the eclipsed pattern (lower). S8

9 E. XPS of micro-1 Ni 2p S 2s Binding Energy / ev Binding Energy / ev Na 1s Binding Energy / ev Figure S4. XPS focusing on the Ni 2p, S 2s and Na 1s regions. S9

10 F. Deconvolution of the S 2s peaks in the XPS of micro-1 and reduced micro-1 micro-1 Intensity / a.u. Band Pos. / ev FWHM / ev Area / % Binding Energy / ev 220 reduced micro-1 Intensity / a.u. Band Pos. / ev FWHM / ev Binding Energy / ev 220 Figure S5. Deconvolution of the S 2s peaks in the XPS of as prepared micro-1 (up) and reduced micro-1 (down). The yellow and green Gauss curves are derived from the nickel bisdithiolene moieties with -1 and 0 oxidation states, respectively. The gray one is assigned to the shake-up peak, which is often observed in bisdithiolene complexes. 41,42 S10

11 G. S 2s peaks in the XPS of nickel bisdithiolene complexes (Bu 4 N) n [Ni(bdt) 2 ] (n = 0, 1, 2) (bdt = 1,2-benzenedithiolate) Table S1. Binding energies of the S 2s peaks in XPS. Binding Energy (S 2s) / ev [Ni(bdt) 2 ] [Ni(bdt) 2 ] [Ni(bdt) 2 ] (Bu 4 N) n [Ni(bdt) 2 ] (n = 0, 1, 2) were prepared according to the methods in the previous literatures. 34,43 S11

12 H. Electrical properties of micro-1 and reduced micro Temperature / K micro-1 ln( ) -3-4 reduced micro /T / K -1 Figure S6. Temperature (T / K) dependence of electric conductivity ( / Scm -1 ) of pelletized micro-1 and reduced micro-1. S12

13 I. Analysis of the moiré structure of nano-1 on HOPG a) b) d) nano-1 c) e) f) (m,n) (0,2) (0,3) (0,4) (1,2) (1,3) (2,2) (2,3) a 1 / nm Figure S7. (a) Observed moiré structure derived from layering single-layer nano-1 and HOPG. (b) FFT image of (a). (c) Highlighted moiré structure extracted by inverse FFT. The greater lattice is the moiré pattern, whereas the smaller one stems from the direct structure of HOPG. (d) Lattice vectors of single-layer nano-1 (a 1, a 2 ) and HOPG (b 1, b 2 ). (e) Proposed model for the moiré pattern. Single-layer nano-1 and HOPG stack with a relative angle of 1.4. (f) Possible pairs of lattice vectors a 1 and a 2 that give the observed moiré periodicity. Judging from the periodicity of nano-1 by SAED and XRD, the most probable pair is m = n = 2. S13

14 To analyze the moiré structure, we referred to a previous study. 44 A moiré structure with hexagonal periodicity of 4.9 nm is created by the two hexagonal lattices, single-layer nano-1 (unknown periodicity) and HOPG (0.246 nm). One of the moiré lattice vectors, M 1, can be represented as M 1 = ma 1 + na 2 = m 0 b 1 + n 0 b 2, (1) where m, n, m 0, and n 0 are integers; and a 1 and a 2 are the unit lattice vectors for the single-layer nano-1; and b 1 and b 2 are those for HOPG. The moiré and HOPG periodicities could be readily highlighted from the STM image by using an inverse FFT (Figure S7 (a) (c)). The moiré unit cell had 12 and 11 atoms of HOPG carbon along the unit vectors, and therefore M 1 = 12b b 2. It follows that the periodicity of the moiré pattern is 4.90 nm, because the periodicity of an HOPG substrate observed in STM is nm. The m, n, and a 1 (= a 2 ) that satisfy equation (1) were thus determined; Figure S7 (f) shows the result. Only m = n = 2 and a 1 = 1.41 nm agree with the SAED and XRD observations for micro-1. The relative angle between the monolayer, single-layer nano-1, and the HOPG, which is 1.4, can also be determined from equation (1). S14

15 J. XPS of nano-1 Figure S8. XPS focusing on the Ni 2p, S 2s and Na 1s regions. S15

16 K. Deconvolution of the S 2s peaks in the XPS of nano-1 and reduced nano-1 Band Pos. / ev FWHM / ev Area / % Binding Energy / ev Band Pos. / ev FWHM / ev Binding Energy / ev 220 Figure S9. Deconvolution of the S(2s) peaks in the XPS of nano-1 (up) and reduced nano-1 (down). The yellow and green Gauss curves are derived from the nickel bisdithiolene moieties with -1 and 0 oxidation states, respectively. The gray one is assigned to the shake-up peak, which is often observed in bisdithiolene complexes. 41,42 S16

17 L. Complete citation of reference 12 in the main text Coleman, J. N.; Lotya, M.; O Neill, A.; Bergin, S. D.; King, P. J.; Khan, U.; Young, K.; Gaucher, A.; De, S.; Smith, R. J.; Shvets, I. V.; Arora, S. K.; Stanton, G.; Kim, H.-Y.; Lee, K.; Kim, G. T.; Duesberg, G. S.; Hallam, T.; Boland, J. J.; Wang, J. J.; Donegan, J. F.; Grunlan, J. C.; Moriarty, G.; Shmeliov, A.; Nicholls, R. J.; Perkins, J. M.; Grieveson, E. M.; Theuwissen, K.; McComb, D. W.; Nellist, P. D.; Nicolosi, V. Science 2011, 331, S17

18 References for Supporting Information (38) Harnisch, J. A.; Angelici, R. J. Inorg. Chim. Acta 2000, 300, (39) Melby, L. R.; Harder, R. J.; Hertler, W. R.; Mahler, W.; Benson, R. E.; Mochel, W. E. J. Am. Chem. Soc. 1962, 84, (40) Langmuir, I.; Schaefer, V. J. J. Am. Chem. Soc. 1938, 60, (41) Zhou, S.; Ichimura, K.; Inokuchi, H. J. Mater. Chem. 1995, 5, (42) Liu, S-G.; Liu, Y-Q.; Zhu, D-B. Synth. Met.1997, 89, (43) Baker-Hawkes, M. J.; Billing, E.; Gray, H. B. J. Am. Chem. Soc. 1966, 88, (44) Tkatchenko, A. Phys. Rev. B. 2007, 75, S18