Electrochemical Synthesis of Various Archetypical Zn 2+, Cu 2+ and Al 3+ Metal Organic Frameworks

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1 - Suplementary information file- Electrochemical Synthesis of Various Archetypical Zn 2+, Cu 2+ and Al 3+ Metal Organic Frameworks A. Martinez Joaristi, J. Juan- Alcañiz, P. Serra- Crespo, F. Kapteijn and J. Gascon* Catalysis Engineering, Chemical Engineering Department, Delft University of Technology, Julianalaan 136, 2628 BL, Delft, The Netherlands * j.gascon@tudelft.nl S1

2 1.- Experimental details The electrodes were metal plates with purities of 99.5% for aluminium, 99.9% for copper and 99.9% for zinc and they were provided by Salomons Metalen (Groningen). The electrodes were inserted between 2 PTFE plates which only allowed a circular opening with a diameter of 25 mm to be in contact with the synthesis solution (4.9 cm2). The potentiostat used was a AUTOLAB PGSTAT302N. Two different views of the electrochemical setup used for the synthesis of MOFs: a) potentiostat AUTOLAB PGSTAT302N and small cell (100 cm3); b) 200 cm3 detailed view of the electrodes. All the chemicals were obtained from Sigma Aldrich and they were used without further purification. The cathode materials were preferably inter alia, i.e., zinc- zinc, copper- copper, aluminum- aluminum. Other materials that can be used are graphite and steel. Scanning Electron Microscopy (SEM) was measured in a JEOL JSM 6500F setup coupled to an Energy Dispersive Spectrometer (EDS) for micro- analysis. N2 sorption analysis was carried out in a Quantachrome Autosorb- 6B. The BET surface area was calculated over the range of relative pressures between and The pore volume was calculated as the uptake (cm3(stp)/g) at a relative pressure of 0.5. The sample was pretreated before measurement, it was outgassed under vacuum at a temperature of 473 K for 16 hrs. S2

3 DRIFT spectra were recorded in a Bruker model IFS66 spectrometer, equipped with a high- temperature cell with CaF 2 windows and a 633 nm laser. The spectra were recorded after 128 scans had been accumulated at a resolution of 4 cm 1. A flow of helium of 10 ml/min was maintained during the measurements. Before collecting the spectra, the different samples were pretreated in a helium flow at 473 K for 30 min. KBr was used as the background. Faraday efficiency Faraday efficiency is calculated as follows: Faraday efficiency = mol metal incorporated MOF mol metal dissolved = MOF obtained g mol metal x g mol MOF MW MOF mol MOF Intensity A time s F C s n e metal S3

4 2.- Electrochemical synthesis of HKUST- 1 A solution with 15 mmol (3.15g) of 1,3,5- benzenetricarboxylic acid (trimesic acid, BTC) and 33 mmol (1.038 g) MTBS in 100 ml 96 vol% ethanol (78.5g) was used. The mixture was heated up to the synthesis temperature in the electrochemical cell with 2 copper electrodes spaced at least 3 cm apart. The material produced was filtered off and cleaned with ethanol at room temperature overnight, then filtered again and dried at 100 C. Figure S 1. Cyclic amperometry for the system HKUST at 40 C, 5-100mA, 10mA/s V is the maximum voltage achieved by the system. Solution conductivity: 530 µs cm - 1. S4

5 Ratio EtOH:H 2O 50:50 75:25 96:4 Figure S 2. SEM micrographs (2 per sample) of electrochemically synthesized HKUST- 1 at room temperature for different EtOH:H 2O volume ratios. 40 C 60 C 80 C Figure S 3. Influence of the synthesis temperature on the morphology and size of HKUST- 1. Each scale bar in different SEM micrographs corresponds to 5 µm. S5

6 Sorption data from electrochemical HKUST a) Influence of the solvent EtOH:H 2 O [v/v] Temperature [ C] Current [ma] Conductivity [ms/cm] a S A [m 2 /g] V p/p 0 =0.5 [cm 3 /g] 50: : : a) conductivity was measured at room temperature before starting the experiments b) Influence of temperature EtOH:H 2 O [v/v] Temperature [ C] Current [ma] Conductivity [ms/cm] a S A [m 2 /g] V p/p 0 =0.5 [cm 3 /g] 96: : : b a) conductivity was measured at room temperature before starting the experiments p/p 0 =0.98 c) Influence of conductivity EtOH:H 2 O [v/v] Temperature [ C] Current [ma] Conductivity [ms/cm] a S A [m 2 /g] V p/p 0 =0.5 [cm 3 /g] 96: : : a) conductivity was measured at room temperature before starting the experiments S6

7 3.- Electrochemical synthesis of ZIF- 8 A solution of 15 mmol (1.232g) of 2- methylimidazole (MeIM) was prepared in 100 ml of solvent which was DMF, MeOH, EtOH or H 2O. If an organic solvent is used, 100 mmol (3.15g) MTBS is used as an electrolyte. If H 2O is used for the synthesis then a 0.1M solution of different electrolytes was used. The mixture was heated up or cooled down to the synthesis temperature in an electrochemical cell with 2 zinc electrodes spaced at least 3 cm apart. The material produced was filtered and cleaned with methanol at room temperature over night, then filtered again and dried at 100 C. 35 Productivity / mg ZIF- 8 h Temp / C Figure S4. Productivity of ZIF- 8 (mg/h) recovered at different temperatures. Experiments done at different temperatures in a H 2O:AcN 70:30 v:v mixture with KCl as the electrolyte and a current of 10 ma with an exposed electrode surface of 4.9 cm 2. S7

8 120 Production / mg ZIF tim e / h Figure S5. The amount of ZIF- 8 produced as a function of time. Experiments performed in a H 2O:AcN 70:30 mixture with KCl as the electrolyte at 0 C ( ) and 5 C ( ) at 10 ma. The exposed electrode surface used was 4.9 cm 2. N 2 sorption ZIF- 8 electrochemical synthesis a) Influence of solvent Solvent/ electrolyte system Temperature [ C] Current [ma] Conductivity a [ms/cm] S A [m 2 /g] V p/p 0 =0.5 [cm 3 /g] DMF/MTBS H 2 O-AcN/KCl MeOH/MTBS H 2 O/MTBS H 2 O-MeOH/ KCl b a) conductivity was measured at room temperature before starting the experiments p/p 0 =0.98 S8

9 4.- Electrochemical synthesis of MIL- 100(Al) A solution of 11.9 mmol (2.5g) BTC in 100 ml of 75 vol% ethanol/25vol% water was used. The mixture was heated up to 60 C in the electrochemical cell with 2 aluminum electrodes spaced at least 3 cm apart. The resulting material is filtered off and cleaned with ethanol at room temperature overnight, then filtered again and dried at 100 C. 10 µm Figure S6. Top: XRD pattern of MIL- 100 (Al) synthesized at 60 o C by the electrochemical method compared with the simulated pattern for MIL- 100(Al). Middle: SEM micrograph of MIL- 100 (Al). Bottom: N 2 adsorption isotherm (blue: adsorption, pink: desorption) (BET = 969 m 2 /g, Pore volume = 0.54 cm 3 /g). S9

10 5.- Electrochemical synthesis of MIL- 53(Al) 9.1 mmol (1.5g) of terephthalic acid (BDC) was dissolved in a solution of 0.1M KCl in 10 vol% DMF in water. The mixture was heated up to 90 C in an electrochemical cell with 2 aluminum electrodes spaced at least 3 co apart. After the synthesis, the solution was filtered, and the filtrate was mixed with DMF and heated up to 150 C to dissolve any remaining BDC for 24 hrs. The powder obtained is then dried at 100 C overnight MIL - 53 np Intensity / a.u. Hydrothermal synthesis Electrochemical synthesis MIL - 53 lp θ / o Figure S7. XRD pattern of MIL- 53 (Al) synthesized electrochemically, resulting in stable open structures; and MIL- 53 (Al) synthesized hydrothermally, resulting in stable closed structure. H 2 O:DMF [v/v] Temperature [ C] Current [ma] Conductivity a [ms/cm] S A [m 2 /g] V p/p 0 =0.5 [cm 3 /g] 90: : : b a) conductivity was measured at room temperature before starting the experiments p/p 0 =0.98 S10

11 Volume / cm 3 g - 1 S TP m 2 /g cm 3 /g P/P 0 Figure S 8. N 2 adsorption isotherm at 77 K for MIL- 53 (Al) synthesized electrochemically. Closed symbols for the adsorption branch, open symbols for the desorption branch. S A= 1243 m 2 /g (BET calculated between p/p 0); V p =0.525 cm 3 /g (calculated at p/p 0=0.5). S11

12 6.- Electrochemical synthesis of NH 2- MIL- 53(Al) The solution consisted of 8.2 mmol (1.5g) of 2- amino terephthalic acid in 0.1M KCl in 10vol% DMF in water. The mixture was heated up to 90 C in an electrochemical cell with 2 aluminum electrodes spaced at least 3 cm apart. After the synthesis, the solution was filtered, and the filtrate was mixed with DMF and heated up to 150 C for 24hrs to dissolve any remaining BDC. The powder obtained was then dried at 100 C overnight Volume / cm 3 g - 1 S TP H 2 O:DMF 0:100 H 2 O:DMF 10:90 H 2 O:DMF 90:10 H 2 O:DMF 100: P/P 0 Figure S 9. N 2 adsorption isotherms at 77 K for NH 2- MIL- 53 synthesized electrochemically in solutions with different H 2O:DMF ratios at 90 o C. Closed symbols for the adsorption branch, open symbols for the desorption branch. H 2 O:DMF [v/v] Temperature [ C] Current [ma] Conductivity a [ms/cm] S A [m 2 /g] V p/p 0 =0.5 [cm 3 /g] 0: b 10: b 90: : a) conductivity was measured at room temperature before starting the experiments p/p 0 =0.98 S12

13 H 2O:DMF 100:0 H 2O:DMF 90:10 H 2O:DMF 10:90 H 2O:DMF 0:100 Figure S 10. SEM micrographs of synthesized NH 2- MIL- 53(Al) samples at varying solvent volume ratios at 90 o C. Scale bar left column at 10 µm, right column at 2 µm. S13

14 Figure S 11. N 2 adsorption isotherms at 77 K for NH 2- MIL- 53 (Al) synthesized electrochemically at different temperatures. Closed symbols for the adsorption branch, open symbols for the desorption branch. H 2 O:DMF [v/v] Temperature [ C] Current [ma] Conductivity a [ms/cm] S A [m 2 /g] V p/p 0 =0.5 [cm 3 /g] 90: b 90: b 90: b 90: a) conductivity was measured at room temperature before starting the experiments p/p 0 =0.98 S14