Reduced Magnetism in Core-Shell Composites

Transcription

1 Reduced Magnetism in Core-Shell Composites Sameh K. Elsaidi, Michael A. Sinnwell, Debasis Banerjee, Arun Devaraj, Ravi K. Kukkadapu, Timothy C. Droubay, Zimin Nie, # Libor Kovarik, Murugesan Vijayakumar, Sandeep Manandhar, Manjula Nandasiri, B. Peter McGrail, # Praveen K. Thallapally * Corresponding author praveen.thallapally@pnnl.gov Physical and Computational Science Directorate, Pacific Northwest National Laboratory, Richland, WA, 99352, United States Chemistry Department, Faculty of Science, Alexandria University, P.O. Box 426 Ibrahimia, Alexandria 21321, Egypt Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA, 99352, United States Department of Mechanical Engineering, University of Texas at El Paso, El Paso, TX # Energy and Environment Technology Directorate, Pacific Northwest National Laboratory, Richland, WA, 99352, United States S1. Syntheses S2. Powder X-Ray Diffraction Data S3. Thermogravimetric Analyses S4. Brunauer-Emmett-Teller (BET) Surface Area Analysis S5. SEM Micrographs S6. TEM Micrographs S7. Magnetic Saturation Data S8. X-ray Absorption Near Edge Spectrum S7. References 1

2 S1. Syntheses Experimental: All reagents and chemicals were used as purchased with no further purification required before use. Synthesis of Fe 3 O 4 Core: Fe 3 O 4 was synthesized using a modified procedure. 1 Typically 5.4 g FeCl 3.9H 2 O and 100 ml ethylene glycol was stirred for 30 min then 11.5 g of sodium acetate was added to the resulting dark yellow solution and stirred for another 1 h. The resulting brown solution transferred to Teflon lined Parr autoclaves, 50 ml in each, and heated for 18 h at 200 ºC. The resulting magnetic black solid of Fe 3 O 4 was washed with water and methanol and collected by the help of magnet. The phase purity was confirmed by powder XRD. Synthesis of Fe 3 O 4 -PSS The functionalization of the Fe 3 O 4 surface with poly(sodium 4-styrenesulfonate) was performed using modified procedure g of Fe 3 O 4 was sonicated for 2 h in a 400 ml solution of 0.3% PSS, then washed with water and collected with help of magnet. The phase purity was confirmed by powder XRD. Synthesis of MIL-101-SO 3 The synthesis was performed using a reported procedure. 3 In a typical synthesis, 3.5 gram of 2- sulfoterephthalic acid, 1.25 grams of CrO 3 and conc. aqueous hydrochloric acid (1 ml) was dissolved in 25 ml water and then transferred to a Teflon lined stainless steel autoclave. The solution was heated at 180ºC for six days. The reaction product was collected by centrifugation and washed with D.I. water (3x time, 50 ml) and methanol (3x times, 100 ml), followed by air drying. The phase purity of the powder was characterized by powder XRD and BET surface area. Synthesis of Fe 3 O 3 MIL101-SO 3 was prepared by the previously reported procedure but we found that in order to grow MIL- 101-SO 3 on the surface of the PSS grafted magnetic core, it is better to sonicate the CrO 3 with the Fe 3 O 4 - PSS for 1 h before the linker is added. This process affords uniform growth of the MOF on the core surface. Fe 3 O 3 was synthesized by the following procedure: Typically 0.14 g of CrO 3 was mixed with 0.5 g of Fe 3 O 4 -PSS in 25 ml water and sonicated for 1 hours then 3.35 g of monosodium 2- sulfoterephthalic acid and 0.8 ml concentrated aqueous hydrochloric acid were added to the mixture and then transferred to a Teflon autoclave and heated for about 6 days at 180 C. The reaction product was harvested and washed with water and methanol. The magnetic brown solid of Fe 3 O 3 was separated from the medium by the help of magnet. The phase purity was confirmed by powder XRD. 2

3 S2. Powder X-Ray Diffraction Data Figure S1. Powder X-ray diffraction patterns for Fe 3 O 4, Pristine MIL-101-SO 3 and Fe 3 O SO 3. 3

4 S3. Thermogravimetric Analyses Figure S2. Thermogravimetric analysis (TGA) for Fe 3 O 4, Pristine MIL-101-SO 3 and Fe 3 O SO 3. 4

5 S4. Brunauer-Emmett-Teller (BET) Surface Area Analysis Figure S3. N 2 Sorption Isotherm of Fe 3 O 4 microsphere collected at 77 K (BET Surface Area = 6 m 2 g -1 ). Figure S4. N 2 Sorption Isotherm of MIL-101-SO 3 collected at 77 K (BET Surface Area = 1368 m 2 g -1 ). 5

6 Figure S5. N 2 Sorption Isotherm of Fe 3 O 3 collected at 77 K (BET Surface Area = 376 m 2 g -1 ). 6

7 S5. SEM Micrographs Figure S6. SEM images of Fe3O4, Fe3O4-PSS and 7

8 Figure S7. Cross sectional images of with internal porosity of the particles. Schematic diagram of core shell particles containing a pore. 8

9 S6. TEM Micrographs Figure S8. TEM images of Fe3O4, Fe3O4-PSS, 9

10 S7. Magnetic Saturation Data Magnetization (emu/g) Magnetization (emu/g) Magnetic Field (Tesla) Magnetic Field (Tesla) (a) (b) Moment_Fe 3 O 4 PSS Moment_Fe 3 O 4 Mil-101 Magnetization (emu/g) Magnetic Field (Tesla) Figure S9. Magnetic saturation of (a) Fe 3 O 4 -PSS (b) Fe 3 O 3 and (c) comparison between the two at room temperature. Saturation magnetization M S of Fe 3 O 4 -PSS (91 emu/g) and coercive field is consistent with magnetite particles > 75nm diameter. Saturation Magnetization (M S ) of Fe 3 O SO 3 (25 emu/g) is reduced by 72% as compared to starting Fe 3 O 4 Reduction in saturation magnetization and coercive field is consistent with oxidation of Fe 2+ on the surface to Fe 3+ where the magnetic core of the particle is reduced in size although the overall size of the particle remain unchanged. Reduction in coercive field may also be explained by a reduction of agglomeration of the particles effectively reducing the domain wall pinning sites which would be expected at grain or nanoparticle boundaries. (c) 10

11 S8. X-ray Absorption Near Edge Spectrum Figure S10. XANES data of Cr L edge of Fe 3 O 3. 11

12 S7. References (1) Deng, H.; Li, X.; Peng, Q.; Wang, X.; Chen, J.; Li, Y. Angew. Chem. Int. Ed. 2005, 44, (2) Zhang, T.; Zhang, X.; Yan, X.; Kong, L.; Zhang, G.; Liu, H.; Qiu, J.; Yeung, K. L. Chem. Eng. J. 2013, 228, (3) Akiyama, G.; Matsuda, R.; Sato, H.; Takata, M.; Kitagawa, S. Adv. Mater. 2011, 23,