Electronic Supplementary Material (ESI) for Materials Chemistry Frontiers. This journal is © the Partner Organisations 2018 Aqueous Immiscible Layered Double Hydroxides – AIM-LDHs Kanittika Ruengkajorn, Christopher M. R. Wright. Nicholas H. Rees, Jean-Charles Buffet and Dermot O’Hare* Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, OX3 1TA, Oxford. E-mail: [email protected] Table of contents 1. General experimental details S2 1.1. Analytical techniques for LDH characterisation S2 1.2. Synthesis of Conventional, AMO- and AIM-LDHs S4 2. Supplementary experimental data S6 2.1 Figures S6 2.2 Tables S36 3 References S47 S1 1. General experimental details 1.1 Analytical techniques for LDH characterisation 1.1.1. X-ray powder diffraction (XRD) X-ray powder diffraction (XRD) results were investigated by using a PANalytical X’Pert Pro diffractometer in reflection mode operating at a voltage of 40 kV and a current intensity of 40 mA with Cu-Kα radiation (λ = 1.5406 Å). LDHs and LDOs powder were placed into stainless steel sample holders. A 1° slit was used. Bragg reflections due to sample holder were observed at 2θ = 43-44° and 50° and from silicon wafer were located at 2θ = 33°, 62° and 69°. The Scherrer’s equation was used to estimate the mean crystallite domain length (CDL) of the LDHs; CDL = Kλ(βcosθ)-1, where CDL = the mean crystallite domain length, K = Scherrer constant, λ = the wavelength of the radiation, and β = the full-width at half-maximum height (FWHM) values of a reflection located at 2θ. Thus, the CDL along c- axis (CDL003) can be calculated from the full-width at half-maximum height values of the (003) Bragg reflection, which is assumed to be the total crystal thickness along the c-axis. Moreover, a layer thickness of LDHs from the d003 spacing using the Bragg’s law; nλ = 2d(sinθ), n is assumed to be one. Therefore, by application of the Bragg’s law and the Scherrer equation, the number of LDH layers can be estimated. Equation 1. Scherrer equation to determine the mean crystalline domain length (CDL).22 퐶퐷퐿 = 퐾휆(훽푐표푠휃)−1 퐾 = 푆푐ℎ푒푟푟푒푟 푐표푛푠푡푎푛푡 휆 = 푡ℎ푒 푤푎푣푒푙푒푛푔푡ℎ 표푓 푡ℎ푒 푟푎푑푎푡표푛 훽 = 푡ℎ푒 푓푢푙푙-푤푑푡ℎ 푎푡 ℎ푎푙푓-푚푎푥푚푢푚 (퐹푊퐻푀) 푣푎푙푢푒 표푓 푎 푟푒푓푙푒푐푡표푛 푎푡 2휃 1.1.2. Fourier transform infrared spectroscopy (FTIR) Fourier transform infrared (FTIR) spectra of samples were recorded on Thermo Scientific Nicolet iS5 FTIR spectrometer in attenuated total reflectance (ATR) mode. Spectra were obtained in the range of 600-4000 cm−1; 50 scans with 4 cm−1 resolution. 1.1.3. Transmission electron microscopy (TEM) Transmission electron microscopy (TEM) was conducted at the Research Complex at Harwell on Jeol JEM-2100 TEM equipped with LaB6 filament at an accelerlating voltage of 200 kV. Prior to analysis, samples were diluted with deionised water and sonicated in deionised water for 15 minutes. A few droplets of the resulting suspension were left to dry on a copper grid covered with a carbon film (300 mesh, Agar scientific). S2 1.1.4. Scanning electron microscopy (SEM) Scanning electron microscopy (SEM) was carried out at the Research Complex at Harwell on a JSM-6610LV low vacuum fitted with EDX spectrometer at an accelerating voltage of 20 kV. Samples were mounted on adhesive carbon tape attached to aluminium stubs then sputter-coated with a 10 nm layer of platinum using a Quorum Q150T ES Sputter Coater to facilitate image. 1.1.5. Zeta potential and Dynamic light scattering (DLS) measurements Zeta potential measurements and DLS analysis were carried out at the Begbroke Science Park, Department of Materials, University of Oxford. LDH Samples were dispersed and sonicated in deionised water at 0.1 wt% for 15 minutes before measurement. The resulting suspension samples were filled in a folded capillary cell and directly measured by using a using a Malvern Zetasizer Nano ZS. 1.1.6. Specific surface area and pore size analysis Specific surface areas and pore size were analysed using the Brunauer–Emmett–Teller (BET) method. The samples were measured from the N2 adsorption and desorption isotherms at 77 K collected from a Micromeritics TriStar II plus. Before each measurement, LDH samples were first degassed overnight at 110 °C. 1.1.7 Thermogravimetric analysis Thermogravimetric analyses were performed by using a Mettler Toledo TGA/DSC 1 system. 15 mg of sample (LDHs) was loaded into alumina crucible and heated from 30–800 °C at a rate of 5 °C/min under a flow of dry N2. Differential thermogravimetric analysis (DTG) is obtained from the 1st derivative of TGA data. 1.1.8 Elemental analysis (EA) Elemental C, H, N analysis was performed by a quantitative oxidative combustion technique by Mr Stephen Boyer at London Metropolitan University. 1.1.9 Inductively coupled plasma mass spectrometer (ICP-MS) Mg and Al content were determined by ICP-MS analysis by Dr. Alaa Abdul-Sada at the University of Sussex on an Agilent 7500 Series ICP-MS in helium collision mode. Approximately, 20 mg of samples were digested in 10 mL of 10% nitric acid solution. These solutions were then diluted by a factor of 100 with dilute nitric acid prior to analysis. Each solution was analysed three times and the data averaged. 1.1.10 Density Tap densities were determined by standard testing method (ASTM D7481-09) using a graduated cylinder. The powder was filled into a volumetric cylinder and a precise weight of sample (m) was measured. The volume was measured before (V0) and after 1000 taps (Vt). S3 The loose bulk and tap densities were calculated by: Loose bulk density = m/V0; Tap density = m/Vt. 1.1.11 Solid state NMR spectroscopy The 1H, 27Al and 13C solid state NMR spectroscopy were performed by Dr. Nicholas H. Rees (University of Oxford) on a Bruker Avance III HD spectrometer equipped with a 9.4 T magnet using 4.0 mm O.D zirconia rotors and a MAS rate of 10 kHz at 399.9, 104.2, and 100.6 MHz, respectively. The high resolution 1H solid state NMR was performed by Dr. Nicholas H. Rees, Dr. Jean- Charles Buffet and Dr. Christopher M. R. Wright (University of Oxford) and Dr. Dinu Iuga (University of Warwick) at the UK 850 MHz Solid-State NMR Facility at the University of Warwick using the Bruker Avance III 850 MHz solid-state NMR spectrometer with 1.3 mm rotors and MAS rate of 60 kHz at 23°C. 1H experiment with background suppression applied referenced to β-Aspagine-Alanine dipeptide. 1.2 Synthesis of Conventional, AMO and AIM LDHs 1.2.1 Synthesis of flower shape like Mg4Al-CO3 LDHs via co-precipitation method The mixed metal salts solution of Mg(NO3)2·6H2O (80 mmol) and Al(NO3)3·9H2O (20 mmol) in 50 mL deionised water was added dropwise into 50 mL of 25 mmol Na2CO3 solution while stirring for 1 hour. Constant pH of 10 was maintained by addition of 4 M NaOH to the reaction mixture using an auto-titrator (Syrris, Atlas Syringe Pump) at feeding rate of 5 mL/min. After stirring at room temperature for 24 hours, the product was filtered and washed with deionised water until pH 7. Then the wet cake was re-dispersed in 100 mL of deionised water and divided into four portions. Each portion was filtered and rinsed with 500 mL of a washing solvent then re-dispersed and stirred in 300 mL of this solvent at room temperature for 4 hours. The solvent was removed by filtration and the obtained LDH was further rinsed with 200 mL of this solvent. The product was dried at room temperature in a vacuum oven overnight. Mg2Al-CO3 LDH and Mg3Al-CO3 LDH were prepared using similar procedure as mentioned above. The mixed metal solution was prepared using 50 mL aqueous solution of 33.3 and 37.5 mmol of Mg(NO3)2·6H2O and 16.7 and 12.5 mmol of Al(NO3)3·9H2O, for Mg2Al-CO3 LDH and Mg3Al-CO3 LDH, respectively. Then the same procedure as mentioned above was used. 1.2.2 Synthesis of platelets shape like Mg4Al-CO3 LDHs via co-precipitation method Synthesis method for platelet shape Mg4Al-CO3 LDHs was modified from Okamoto et al.. An aqueous solution of Mg(NO3)2·6H2O (40 mmol), Al(NO3)3·9H2O (10 mmol) and urea (160 mmol) in 100 mL deionised water was prepared. The solution was transferred to a Teflon-lined autoclave and heated in an oven at 100 °C for 24 hours. After cooling to room temperature, the precipitate products were washed several times with deionised water by filtration until pH 7. Then the wet cake was re-dispersed in 100 mL of deionised water and S4 separated into four portions. A portion of dispersion was filtered and followed steps as mentioned above. Solvents used were acetone, ethanol, 1-hexanol, and ethyl acetate. 1.2.3. Effect of solvent types: AMO vs. AIM solvents Both AMO and AIM solvents were compared in this study. The AMO solvent was ethanol, the AIM solvents were ethyl acetate, diethyl ether, hexane and toluene. S5 2. Supplementary experimental data 2.1 Figures 003 006 012 113 110 * 015 018 Water Acetone Ethanol Isopropyl alcohol 1-Methyl-2-pyrrolidinone Ethylacetate 1-Butanol 1-Hexanol Triethylamine Nitromethane Methyl ethyl ketone Relative intensity (a.u.) intensity Relative Diethyl ether Tert-butyl methyl ether Toluene Hexane Chloroform 10 20 30 40 50 60 70 2(o) Fig. S1. Powder X-ray diffraction patterns of some solvent-treated Mg4Al–CO3 LDHs. * is a Bragg reflection from the Al sample holder.