SUPPLEMENTARY INFORMATION

Transcription

1 DOI: /NCHEM.2515 Fabrication of carbon nanorods and graphene nanoribbons from a metal organic framework Pradip Pachfule, 1 Dhanraj Shinde, 2 Mainak Majumder 2 and Qiang Xu* 1 1 National Institute of Advanced Industrial Science and Technology (AIST), Ikeda, Osaka , Japan. q.xu@aist.go.jp 2 Nanoscale Science and Engineering Laboratory (NSEL), Mechanical and Aerospace Engineering Department, Monash University, Clayton, VIC 3800, Australia. NATURE CHEMISTRY 1

2 Contents List Supplementary Section 1. Materials and instrumentation Supplementary Section 2. Characterization of MOF-74 Supplementary Section 3. Synthesis and characterization of MOF-74-Rod Supplementary Section 4. Synthesis and characterization of CNRod Supplementary Section 5. Synthesis and characterization of GNRib Supplementary Section 6. Synthesis and characterization of MPC Supplementary Section 7. Electrochemical measurements Supplementary Section 8. References NATURE CHEMISTRY 2

3 Supplementary Section 1. Materials and instrumentation Materials All the reagents and solvents used for the synthesis were commercially available and used without further purification. The anhydrous zinc acetate (98 %) and 2,5-dihydroxyterephtalic acid (> 98%) were purchased from Wako Pure Chemical Industries Ltd. and TCI Chemicals, respectively. General instrumentation and methods A bath sonicator (VELVO, VS-N100S, 100 W, 40 khz) was used for the experiments with ultrasonication. Thermo-gravimetric analyses (TGA) were carried out on a Rigaku Thermo plus EVO2/TG-DTA analyzer under argon atmosphere at a heating rate of 5 C min 1 within the temperature range of C. Powder X-ray diffraction (PXRD) measurements were performed on a Rigaku Ultima IV X-ray diffractometer with a Cu Kα source. Raman spectra were obtained using a Renishaw Confocal micro-raman Spectrometer equipped with a HeNe (632.8 nm) laser operating at 10% power. Conductivity was measured by an Agilent B2902A source measuring unit (SMU) with Agilent Quick IV software. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) analyses of MOF and carbon samples were analyzed by a FEI Nova NanoSEM 450 FE-SEM. To avoid charging during SEM analyses, we coated all MOF samples with a thin layer of gold prior to analyses. Transmission electron microscopy (TEM) and high-angle annular dark-field scanning TEM (HAADF-STEM) measurements for the detailed microstructure and composition information were executed on FEI TECNAI G 2 at an accelerating voltage of 200 kv. Atomic force microscopy (AFM) measurements (imaging) were made using a JPK Nanowizard 3 AFM equipped with capacitive sensors to ensure accurate reporting of height, z, and x y lateral distances. Imaging was performed in the tapping mode using Bruker NCHV model cantilevers, with nominal resonant frequencies of 340 spring constants of N/m. Images were NATURE CHEMISTRY 3

4 obtained with a set-point force of 1 nn. Elemental (CHNO) analyses were performed on EA1110 (CE instruments) and FLASH EA1112 (CE instruments), respectively. The metal contents of the CNRod and GNRib were analyzed using ICP-OES on Thermo Scientific icap6300. X-ray photoelectron spectroscopic (XPS) measurements were conducted on a Shimadzu ESCA-3400 X-ray photoelectron spectrometer using a Mg Kα source (10 kv, 10 ma). Fourier transform infrared spectroscopy (FTIR) analyses were carried on Bruker IFS 66v/S. N 2 sorption measurements were performed on a volumetric sorption instrument (BELSORP-Max). The H 2 (77 K) and CO 2 (273 and 298 K) sorption measurements were performed using BELSORP-MINI-II adsorption equipment. Prior to the gas sorption studies of MOF-74-Rod and MOF-74, the solvent exchanged samples were dried under a dynamic vacuum (<10-3 Torr) at room temperature (RT) followed by heating at 80 C for 12 h and 150 C for 12 h. The samples of CNRod, GNRib and MPC were evacuated at 150 C for 24 h prior to the gas sorption measurements. Using the N 2 adsorption isotherms, the surface areas were calculated using Brunauer-Emmett-Teller (BET) method and pore size distributions were calculated using the non-localized density functional theory (NLDFT) method. The heat of adsorption (Q st ) for CO 2 adsorption was calculated using the isotherms at 273 and 293 K. Electrochemical measurements All the electrochemical measurements were carried out using a two electrode capacitor cell with an aqueous solution of sulfuric acid (1.0 M) as electrolyte. Each electrode was constructed using 2.0 mg of carbon samples without adding any binder and conductive agents, where a glassy paper separator was sandwiched between two electrodes and platinum plates were used as electronic collectors. Two identical electrodes were adopted as the cathode and anode for the cell configuration. NATURE CHEMISTRY 4

5 The electrochemical experiments were accomplished under ambient conditions. Before the measurements, the capacitor cell was evacuated under vacuum for 3 h to allow the electrode material fully soaked in the electrolyte. Cyclic voltammograms at different sweep rates for the capacitor were carried out on a Solartron electrochemical workstation (SI1287). The specific capacitance is calculated according to the following equation (1): C = 2 ΔQ / (ΔV m).. (1) Where ΔQ is the charge integrated from the whole voltage range, ΔV is the whole voltage difference, and m is the mass of carbon on an electrode. Galvanostatic charge/discharge examinations at various current densities were performed on a Solartron electrochemical workstation (SI1287) and a voltage range of 0 to 1 V was set. Specific capacitance of each electrode was calculated according to the following equation (2): C = 2 I Δt / (ΔV m).. (2) Where I is the discharge current, Δt is the discharge time, ΔV is the voltage difference within the discharge time Δt, and m is the mass of carbon on an electrode. The factor of two in these equations comes from the fact that the total capacitance measured from the test cells is the sum of two equivalent single electrode capacitors in series. For the cyclic voltammetry and charge-discharge analyses using GNRib in ionic liquid, the voltage window was set from 0 3 V and 1-ethyl-3-methylimidazolium dicyanamide ionic liquid was used as electrolyte. NATURE CHEMISTRY 5

6 Supplementary Section 2. Characterization of MOF-74 Supplementary Figure 1 SEM analyses of MOF a, Low magnification SEM image of MOF- 74. b, c, SEM images of as-synthesized MOF-74 showing the formation of microcrystalline MOF without any specific morphology. NATURE CHEMISTRY 6

7 Supplementary Section 3. Synthesis and characterization of MOF-74-Rod Supplementary Figure 2 Synthesis and characterization of MOF-74-Rod. a, Modulator-assisted synthesis of MOF-74 in a rod-shaped morphology (MOF-74-Rod). b, Crystal structure of MOF-74 showing the coordination of 2,5-dihydroxyterephtalic acid with Zn-metal centers and oxo-bridged secondary building unit (SBU). c, SEM image of MOF-74-Rod showing the rod-shaped morphology. NATURE CHEMISTRY 7

8 Supplementary Figure 3 Thermo-gravimetric analyses of MOF-74-Rod and MOF-74 under an argon atmosphere showing the higher solvent loss for MOF-74-Rod below 150 C. The weight loss above 850 C corresponds to the removal of Zn-metal from the matrix. NATURE CHEMISTRY 8

9 Supplementary Table 1 Summary of dimensions and surface areas of MOF-74-Rod and MOF-74. Name Shape Width Dimensions Length Height/ thickness Surface area (m 2 g -1 ) MOF-74-Rod Rod nm nm nm 377 MOF-74 Microcrystals µm 411 NATURE CHEMISTRY 9

10 Supplementary Section 4. Synthesis and characterization of CNRod Supplementary Figure 4 Synthesis and characterization of CNRod. a, Scheme of synthesis of rod-shaped carbon nanostructures (CNRod) from MOF-74-Rod through the morphology-preserved thermal transformation. b-d, SEM (b, c) and low-magnification TEM (d) images of CNRod showing the rod-shaped morphology. NATURE CHEMISTRY 10

11 Supplementary Figure 5 TEM and AFM analyses of CNRod. a-f, TEM images of CNRod showing the formation of carbon nanorods of moderate aspect ratio. g, AFM image of CNRod conforming the formation of one-dimensional structures with moderate dimensions. The corresponding height profile shows the formation of rod-like nanostructures with a height of nm. NATURE CHEMISTRY 11

12 Supplementary Section 5. Synthesis and characterization of GNRib Supplementary Figure 6 Synthesis and characterization of GNRib. a, Scheme and probable mechanism of the synthesis of graphene nanoribbons (GNRib) from MOF-74-Rod through morphology-preserved thermal transformation followed by sonication and thermal activation. b-d, SEM (b, c) and low-magnification TEM (d) images of GNRib showing the ribbon-like morphology as a result of exfoliation of CNRod. NATURE CHEMISTRY 12

13 Supplementary Figure 7 TEM and AFM analyses of GNRib. a-c, Low magnification (a) and high magnification TEM (b, c) image of GNRib showing the distinct formation of graphene nanoribbons having moderate dimensions and excellent flexibility. d-f, High magnification TEM images of GNRib showing the graphitic nature of nanoribbons. g, AFM images of GNRib confirming the formation of two-dimensional graphene nanoribbons. The corresponding height profiles show the formation of sheet-like nanostructures with a height of nm, corresponding to 2-6 layers. NATURE CHEMISTRY 13

14 Supplementary Figure 8 XPS analyses of CNRod and GNRib. a, The XPS spectra of CNRod and GNRib showing the presence of C, low contents of N and O, and no signals from Zn. b, The XPS spectra of CNRod and GNRib in the Zn 2p region showing no signals for Zn in the samples. NATURE CHEMISTRY 14

15 Supplementary Figure 9 EDS analyses of MOF-74-Rod, CNRod, and GNRib. a-c, EDS spectra of MOF-74-Rod (a), CNRod (b), and GNRib (c). The absence of peaks for Zn and K in the EDS spectra of CNRod and GNRib confirms the removal of Zn and K from the samples. The silicon (Si) signals are from the sample holder. NATURE CHEMISTRY 15

16 Supplementary Figure 10 FTIR analysis for the product of thermal treatment of CNRod with KOH. a-c, FTIR spectra of CNRod (a), K 2 CO 3 (b), and the CNRod sample treated with KOH at 800 C for 2 h (c). c shows the peaks from K 2 CO 3, validating the mechanism of carbon activation following the reaction pathway 3 : 6KOH + 2C 2K + 3H 2 + 2K 2 CO 3. NATURE CHEMISTRY 16

17 Supplementary Section 6. Synthesis and characterization of MPC The activated sample of MOF-74 (0.5 g) was transferred into a ceramic boat and placed into a temperature-programmed furnace under an argon flow. The sample was heated slowly from room temperature to 1000 C in 5 h and then kept at 1000 C for 4 h under flowing argon gas. The furnace was allowed to cool down to room temperature naturally in argon atmosphere. The resultant black carbon material of MPC in quantitative yield was collected directly from the ceramic boat and used without further purification. Supplementary Figure 11 TEM analyses of MPC. a, Low-magnification TEM image of MPC. b, c, High-magnification TEM images showing the formation of microporous carbon through the morphology-preserved thermal transformation of MOF-74. NATURE CHEMISTRY 17

18 Supplementary Table 2 Summary of dimensions and surface areas of CNRod, GNRib and MPC. Name Shape Width Size Length Height/ thickness Surface area (m 2 g -1 ) CNRod Rod nm nm nm 1559 GNRib Ribbon nm nm nm 1492 MPC Non-specific µm 1286 Supplementary Table 3 Summary of elemental (CHNO) and ICP analyses of CNRod and GNRib. Name of Material CHNO Analyses (%) ICP Analyses (%) C H N O Zn K CNRod GNRib NATURE CHEMISTRY 18

19 Supplementary Figure 12 H 2 and CO 2 sorption analyses of CNRod, GNRib and MPC. a, H 2 adsorption (filled circles) and desorption (open circles) isotherms at 77 K. b, c, CO 2 adsorption (filled circles) and desorption (open circles) isotherms at 273 K (b) and 293 K (c). Inset of (c): heats of CO 2 adsorption (Q st ) calculated using isotherms at 273 and 293 K. NATURE CHEMISTRY 19

20 Supplementary Section 7. Electrochemical measurements Supplementary Figure 13 Electrochemical analyses of GNRib, CNRod and MPC. a, b, Galvanostatic charge discharge curves for GNRib at the current densities of 50, 100, 250 and 500 ma g -1 (a) and 1, 3, 5, 7 and 10 A g -1 (b). c, d, Galvanostatic charge discharge curves for CNRod at the current densities of 50, 100, 250 and 500 ma g -1 (c) and 1, 3, 5, 7 and 10 A g -1 (d). e, f, Galvanostatic charge discharge curves for MPC at the current densities of 50, 100, 250 and 500 ma g -1 (e) and 1, 3, 5, 7 and 10 A g -1 (f). NATURE CHEMISTRY 20

21 Supplementary Figure 14 Electrochemical analyses of GNRib, CNRod and MPC. a, Representation of specific capacitance as a function of current density for GNRib, CNRod and MPC calculated from charge-discharge curves. b, Cycling stability of GNRib, CNRod and MPC at 10 mv s - 1. NATURE CHEMISTRY 21

22 Supplementary Table 4 Summary of electrochemical results of GNRib, CNRod and MPC (Electrolyte: 1 M H 2 SO 4 ). Name of Material Specific Capacitance (F g -1 ) Cyclic Voltammetry (mv s -1 ) Charge-Discharge (A g -1 ) Electrical Conductivity (S cm -1 ) GNRib CNRod MPC NATURE CHEMISTRY 22

23 Supplementary Figure 15 Electrochemical analyses of GNRib using ionic liquid as electrolyte. a, Comparative cyclic voltammograms at different sweep rates using GNRib as an electrode material and ionic liquid (1-ethyl-3-methylimidazolium dicyanamide) as an electrolyte. Inset: structure of 1-ethyl- 3-methylimidazolium dicyanamide. b, Comparative galvanostatic charge discharge curves for GNRib at current densities of 50, 100, 250 and 500 ma g -1 using ionic liquid as electrolyte. c, Nyquist plot for GNRib in ionic liquid as an electrolyte, showing the imaginary part versus the real part of impedance. Inset: impedance data in the high-frequency range. d, Bode phase plots for GNRib showing the phase angle (theta) close to 77. Supplementary Table 5 Summary of supercapacitor performance of GNRib (Electrolyte: 1-ethyl-3-methylimidazolium dicyanamide). Name Specific Capacitance (F g -1 ) Cyclic Voltammetry (mv s -1 ) Charge-Discharge (ma g -1 ) GNRib NATURE CHEMISTRY 23

24 Supplementary Table 6 Comparative supercapacitor performance of GNRib, CNRod and MPC with literature reported materials. Name of material Type of material Precursor Specific Capacitance (F g -1 ) Sweep Rate/ Current Density Electrolyte Reference Carbon nanotubes Carbon nanotubes Acetylene mv s -1 1 M LiClO 4 4 Carbon aerogels RFaerogel Resorcinolformaldehy de aerogel 40* 5 ma cm -2 1 M H 2 SO 4 5 MWNTs Carbon nanotube MWNT Thin Films mv s -1 1 M H 2 SO butyl-3- a-mego Carbon Graphene oxide 166* 5.7 A g -1 methylimidazolium 7 tetrafluoro-borate ZTC Carbon FAU (Zeolite) 190* 1.0 A g M TEABF 4 8 NG Graphene Graphene 280* 1.0 A g -1 1 M TEABF 4 9 fg-3h Graphene Graphene oxide 276* 0.1 A g -1 1 M H 2 SO 4 10 Graphene Graphene GOC oxide and nano- oxide and nano- 143* 0.2 A g -1 1 M H 2 SO 4 11 diamond diamond AS-ZC- 800 Carbon ZIF-8 (ZIF) mv s -1 1 M H 2 SO 4 12 NATURE CHEMISTRY 24

25 Al-MIL- MIL-C-2 Carbon 101-NH mv s -1 1 M H 2 SO 4 13 (MOF) CNRod Carbon nanorods MOF-74- Rod (MOF) * 10 mv s ma g -1 1 M H 2 SO 4 This work GNRib Graphene nanoribbo ns MOF derived Carbon nanorods * 10 mv s ma g -1 1 M H 2 SO 4 This work MPC Carbon MOF- 74(Zn) (MOF) * 10 mv s ma g -1 1 M H 2 SO 4 This work * Specific capacitance values are calculated from charge-discharge curves. NATURE CHEMISTRY 25

26 Supplementary Table 7 Comparison of I D /I G ratio of GNRib, CNRod and MPC with literature reported materials. Name of the material Source material I D /I G ratio Reference Graphene nanoribbons Graphene oxide nanoribbons (GONR) Graphene nanoribbons Multiwalled carbon nanotubes (MWCNT) Multiwalled carbon nanotubes (MWCNT) Ferrocene and thiophene in ethanol > >1 15 > Graphene nanoribbons C-face 4H- and 6H-SiC wafers >1 17 Graphene nanoribbons (GNR) Graphene nanoribbons (GNRs) Graphene nanoribbons (GNR) Aligned graphene nanoribbon (GNR) Graphene nanoribbons (GNRs) Multiwalled carbon nanotubes (MWCNT) Multiwalled carbon nanotubes (MWCNT) Multiwalled carbon nanotubes (MWCNT) Single-walled and few-walled carbon nanotube (CNT) Multiwalled carbon nanotubes (MWCNT) Carbon nanorods (CNRod) Graphene nanoribbons (GNRib) MOF-74-Rod 1.01 This work MOF-derived carbon nanorods 1.09 This work NATURE CHEMISTRY 26

27 Supplementary Section 8. References 1. Rowsell, J. L. C. & Yaghi, O. M. Effects of functionalization, catenation, and variation of the metal oxide and organic linking units on the low-pressure hydrogen adsorption properties of metal organic frameworks. J. Am. Chem. Soc. 128, (2006). 2. Yue, Y. et al. Template-free synthesis of hierarchical porous metal organic frameworks. J. Am. Chem. Soc. 135, (2013). 3. Lillo-Ródenas, M. A., Cazorla-Amorós, D. & Linares-Solano, A. Understanding chemical reactions between carbons and NaOH and KOH: An insight into the chemical activation mechanism. Carbon 41, (2003). 4. Chen, J. H. et al. Electrochemical characterization of carbon nanotubes as electrode in electrochemical double-layer capacitors. Carbon 40, (2002). 5. Kim, S. J., Hwang, S. W. & Hyun, S. H. Preparation of carbon aerogel electrodes for supercapacitor and their electrochemical characteristics. J. Mater. Sci. 40, (2005). 6. Lee, S. W. et al. Layer-by-layer assembly of all carbon nanotube ultrathin films for electrochemical applications. J. Am. Chem. Soc. 131, (2009). 7. Zhu, Y. et al. Carbon-based supercapacitors produced by activation of graphene. Science 332, (2011). 8. Itai, H., Nishihara, H., Kogure, T. & Kyotani, T. Threedimensionally arrayed and mutually connected 1.2-nm nanopores for high-performance electric double layer capacitor. J. Am. Chem. Soc. 133, (2011). 9. Jeong, H. M. et al. J. W. Nitrogen-doped graphene for highperformance ultracapacitors and the importance of nitrogen-doped sites at basal planes. Nano Lett. 11, (2011). 10. Lin, Z. Y. et al. Superior capacitance of functionalized graphene. J. Phys. Chem. C 115, (2011). 11. Sun, Y. Q. et al. Highly conductive and flexible mesoporous graphitic films prepared by graphitizing the composites of graphene oxide and nanodiamond. J. Mater. Chem. 21, (2011). 12. Amali, A. J., Sun, J.-K. & Xu, Q. From assembled metal organic framework nanoparticles to hierarchically porous carbon for electrochemical energy storage. Chem. Commun. 50, (2014). 13. Sun, J.-K. & Xu, Q. From metal organic framework to carbon: toward controlled hierarchical pore structures via a double-template approach. Chem. Commun. 50, (2014). 14. Kosynkin, D. V. et al. Longitudinal unzipping of carbon nanotubes to form graphene nanoribbons. Nature 458, (2009). 15. Zhang, Z. et al. Transforming carbon nanotube devices into nanoribbon devices. J. Am. Chem. Soc. 131, (2009). NATURE CHEMISTRY 27

28 16. Campos-Delgado, J. et al. Bulk production of a new form of sp 2 carbon: Crystalline graphene nanoribbons. Nano Lett. 8, (2008). 17. Tongay, S. et al. Drawing graphene nanoribbons on SiC by ion implantation. Appl. Phys. Lett. 100, (2012). 18. Jiao, L. et al. Narrow graphene nanoribbons from carbon nanotubes. Nature 458, (2009). 19. Shinde, D. B. et al. Electrochemical unzipping of multi-walled carbon nanotubes for facile synthesis of high-quality graphene nanoribbons. J. Am. Chem. Soc. 133, (2011). 20. Jiao, L. et al. Facile synthesis of high quality graphene nanoribbons. Nat. Nanotech. 5, (2010). 21. Jiao L. Y. et al. Aligned graphene nanoribbons and crossbars from unzipped carbon nanotubes. Nano Res. 3, (2010). 22. Kosynkin, D. V. et al. Highly conductive graphene nanoribbons by longitudinal splitting of carbon nanotubes using potassium vapor. ACS Nano 5, (2011). NATURE CHEMISTRY 28