Supplementary Information. Hydrogen absorption in 1 nm Pd clusters confined in. MIL-101(Cr)

Transcription

1 Electronic Supplementary Material (ESI) for Journal of Materials Chemistry A. This journal is The Royal Society of Chemistry 2017 Supplementary Information Hydrogen absorption in 1 nm Pd clusters confined in MIL-101(Cr) Abdelmalek Malouche 1, Gabriela Blanita 2, Dan Lupu 2, Julie Bourgon 1, Jaysen Nelayah 3, Claudia Zlotea 1* *corresponding author claudia.zlotea@icmpe.cnrs.fr Table SI-1. Chemical analysis of x-pd@mil-101 (x = 5, 10, 15 and 20). Figure SI-1. TEM images and related particle size histograms for x-pd@mil-101 (x = 5, 10, 15 and 20). Figure SI-2. SEM images for x-pd@mil-101 (x = 5, 10, 15 and 20). Figure SI-3. Experimental and simulated XRD patterns of MIL-101. Figure SI-4. Thermogravimetric analysis of MIL-101 under air. Figure SI-5. Hydrogen absorption PCI curves for all composites expressed as equilibrium pressure vs. H/M. Figure SI-6. XAS spectra for Pd bulk under air (black) and Pd@MIL-101 under 1 bar He (blue) and H 2 (red) at 300 K. Figure SI-7. Comparison of the module of FT for bulk, 2.5 nm and 1 nm Pd at room temperature. Figure SI-8. Comparison between FT experimental (black) and fitted (red) by EXAFS refinements at Pd K edge for bulk Pd. Figure SI-9. Comparison between FT experimental (black) and fitted (red) by EXAFS refinements at Pd K edge for Pd@MIL-101 under He. Figure SI-10. Comparison between FT experimental (black) and fitted (red) by EXAFS refinements at Pd K edge for Pd@MIL-101 under H 2. 1

2 Table SI-1. Chemical analysis of (x = 5, 10, 15 and 20). Sample Pd content (wt%) ICP-MS 5-Pd@MIL (±0.2) 10-Pd@MIL (±0.4) 15-Pd@MIL (±0.7) 20-Pd@MIL (±0.9) The palladium content in all composites was determined quantitatively by inductively coupled plasma mass spectrometry (ICP-MS) using an ELAN DRC-e Perkin Elmer, after calibration with a 10 µg/ml Pd in HNO 3 standard solution (Multi-element Calibration Standard 3) and digesting the samples by standard protocols in HNO 3 /HF/H 2 O. 2

3 Figure SI-1. TEM images and related particle size histograms for (x = 5, 10, 15 and 20). 50 nm Particle size (nm) 5-Pd@MIL nm Particle size (nm) 10-Pd@MIL-101 3

4 50 nm Particle size (nm) 15-Pd@MIL nm Particle size (nm) 20-Pd@MIL-101 4

5 Figure SI-2. SEM images for (x = 5, 10, 15 and 20). 5-Pd@MIL Pd@MIL-101 5

6 6

7 Figure SI-3. Experimental and simulated XRD patterns of MIL Intensity (a. u.) simulated MIL-101 MIL θ (⁰)

8 Figure SI-4. Thermogravimetric analysis under air (100 ml min -1 ) with heating rate of 10 C min -1. Weight (%) TGA DTG Deriv. weight (%/min.) Temperature (⁰C)

9 Figure SI-5. Hydrogen absorption PCI curves at room temperature for all composites and bulk Pd expressed as equilibrium pressure vs. capacity (H/Pd). 1 Pressure (bar) E H/Pd bulk Pd 5-Pd@MIL Pd@MIL Pd@MIL Pd@MIL-101 On the overall, the dispersion among PCI curves for all composites is satisfactory and no plateau pressure could be observed, irrespective of Pd content. The dispersion of PCI curves is small at low pressures and slightly increases with pressure. This can be understood by mainly two factors: accumulation of errors with rising pressure, typical for volumetric measurements and the large uncertainties in PCI measurements with decreasing the weight of the active material (decreasing the Pd content). Consequently, only the PCI curve for the highest Pd content was discussed in the manuscript. 9

10 Figure SI-6. XAS spectra for Pd bulk under air (black) and under 1 bar He (blue) and H 2 (red) at 300 K. 1.2 Normalized adsorption E(eV) Pd bulk Pd@MIL-101 He Pd@MIL-101 H 2 10

11 Figure SI-7. Comparison of the module of FT for bulk, 2.5 nm and 1 nm Pd at room temperature. 20 bulk 1 nm 2.5 nm FT k 1 (k) R(Å) The XAS data for 2.5 nm Pd nanoparticles are taken from our previous results reported in J. Am. Chem. Soc., 2010, 132, Since the XAS data for 2.5 nm Pd nanoparticles are recorded after air exposure without H 2 pre-treatment, these nanoparticles are slightly oxidized, as proven by the small peak at around 1.75 Å typical for Pd-O distance. 11

12 Figure SI-8. Comparison between FT experimental (black) and fitted (red) by EXAFS refinements at Pd K edge for bulk Pd FT experiment fit R( Å ) 12

13 Figure SI-9. Comparison between FT experimental (black) and fitted (red) by EXAFS refinements at Pd K edge for Pd@MIL-101 under He FT 0-5 experiment fit R( Å ) 13

14 Figure SI-10. Comparison between FT experimental (black) and fitted (red) by EXAFS refinements at Pd K edge for Pd@MIL-101 under H FT 0-5 experiment fit R( Å ) 14