Supporting Information Hierarchical Nanocomposite by Integrating Reduced Graphene Oxide and Amorphous Carbon with Ultrafine MgO Nanocrystallites for Enhanced CO 2 Capture Ping Li, and Hua Chun Zeng* Department of Chemical and Biomolecular Engineering, Faculty of Engineering, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260 *Email: chezhc@nus.edu.sg Number of Pages: 17 Number of Tables: 1 Number of Figures: 14 S-1
Figure S1. FTIR spectrum of the graphene oxide used in this work. The sample was prepared by a modified Hummer's method (see Experimental Section). S-2
Figure S2. SEM and TEM images of rgo@mg-eg-x precursors: (a, b) rgo@mg- EG-2, (c, d) rgo@mg-eg-10, and (e, f) rgo@mg-eg-15. S-3
Figure S3. (a) SEM and (b) TEM images of flower-like Mg-EG complex precursor. S-4
Figure S4. FTIR spectra of (a) rgo@mg-eg-2, (b) rgo@mg-eg-10, (c) rgo@mg- EG-15, and (d) Mg-EG precursors. S-5
Figure S5. TGA curves of (a) rgo@mg-eg-2, (b) rgo@mg-eg-10, (c) rgo@mg- EG-15, and (d) Mg-EG precursors. S-6
Figure S6. FTIR spectrum of the as-obtained rgo@mgo/c-5 nanocomposite. Note that when rgo@mgo/c-5 sample is exposed to the atmosphere, H2O and CO2 molecules are easily adsorbed onto the MgO surface. Thus the bands assigned to the carbonate species and adsorbed H2O are unavoidable to appear in the FTIR spectrum. S-7
Figure S7. SEM and TEM images of rgo@mgo/c-x nanocomposites: (a-c) rgo@mgo/c-2, (d-f) rgo@mgo/c-10, and (g-i) rgo@mgo/c-15. S-8
Figure S8. (a) SEM and (b, c) TEM images of flower-like MgO/C nanocomposite. S-9
Figure S9. N2 adsorption desorption isotherms and the corresponding NLDFT pore size distribution curves of rgo@mgo/c-x nanocomposites: (a, b) rgo@mgo/c-2, (c, d) rgo@mgo/c-5, (e, f) rgo@mgo/c-10, and (g, h) rgo@mgo/c-15. S-10
Figure S10. (a) N2 adsorption desorption isotherm and (b) the NLDFT pore size distribution curve of the flower-like MgO/C nanocomposite. Figure S11. (a, b) SEM images of the commercial MgO sample. S-11
Figure S12. The normalized CO2 sorption capacities (based on MgO) of the sorbents at 27 C and 1 bar of CO2. S-12
Figure S13. TEM images of the alkali metal salt promoted rgo@mgo/c-5 nanocomposites: (a) KNO3-promoted, (b) K2CO3-promoted, and (c) NaNO3-promoted. S-13
Figure S14. TEM image of the spent rgo@mgo/c-5 nanocomposite. S-14
Table S1. A summary of CO2 capture capacities on different MgO-based sorbents from the literature. Sorbent Sorption temperature ( C) Regeneration temperature ( C) CO 2 partial pressure (bar) CO 2 sorption capacity (wt%) Ref. rgo@mgo/c-5 27 400 1 31.5 This 27 400 0.15 22.5 work MgO/activated carbon 30 400 1 ca. 9.9 1 Mesoporous carbon supported MgO 25 200 1 9.2 2 Carbon doped porous MgO- ZnO 25 400 1 4.21 Carbon doped porous MgO 25 400 1 5.31 3 Porous pure MgO 25 400 1 6.12 Ordered mesoporous MgO/carbon spheres 25 1.2 11.88 4 MgO/C 27 400 1 27.6-30.9 5 Foam-like MgO 25 600 1 ca. 12.0 6 Mesoporous MgO 25 800 1 8.0 7 Mesoporous MgO-Al 2O 3 30 400 1 3.16-5.44 8 Mesoporous MgO-TiO 2 25 150 1 2.1 Mesoporous MgO 25 150 1 0.33 9 Porous MgO 50 450 1 6.44-7.59 10 Mesoporous MgO-Al 2O 3 60 450 1 0.1 1.34 1.32 11 MgO-NP1 60 600 1 0.7 12 Multi-core MgO NPs@C 27 500 0.15 7.7 13 Nanoporous MgO/C 27 500 0.15 5.2-9.2 14 Mesoporous Mg Zr solid oxides 30 400 0.1 3.56-5.63 15 Pure MgO 30 400 0.1 0.66 MgO-Al 2O 3 60 350 0.13 4.3 16 S-15
References: (1) Li, Y. Y.; Han, K. K.; Lin, W. G.; Wan, M. M.; Wang, Y.; Zhu, J. H. J. Mater. Chem. A 2013, 1, 12919. (2) Bhagiyalakshmi, M.; Hemalatha, P.; Ganesh, M.; Mei, P. M.; Jang, H. T. Fuel 2011, 90, 1662. (3) Li, Y. Y.; Wan, M. M.; Sun, X. D.; Zhou, J.; Wang, Y.; Zhu, J. H. J. Mater. Chem. A 2015, 3, 18535. (4) Chen, A.; Yu, Y.; Li, Y.; Li, Y.; Jia, M. Mater. Lett. (5) Li, P.; Liu, W.; Dennis, J. S.; Zeng, H. C. ACS Applied Materials & Interfaces 2017, 9, 9592. (6) Han, K. K.; Zhou, Y.; Lin, W. G.; Zhu, J. H. Microporous Mesoporous Mater. 2013, 169, 112. (7) Bhagiyalakshmi, M.; Lee, J. Y.; Jang, H. T. Int. J. Greenhouse Gas Control 2010, 4, 51. (8) Han, S. J.; Bang, Y.; Lee, H.; Lee, K.; Song, I. K.; Seo, J. G. Chem. Eng. J. 2015, 270, 411. (9) Jeon, H.; Min, Y. J.; Ahn, S. H.; Hong, S.-M.; Shin, J.-S.; Kim, J. H.; Lee, K. B. Colloids and Surfaces A: Physicochemical and Engineering Aspects 2012, 414, 75. (10) Ding, Y.-D.; Song, G.; Zhu, X.; Chen, R.; Liao, Q. RSC Adv. 2015, 5, 30929. (11) Jiao, X.; Li, H.; Li, L.; Xiao, F.; Zhao, N.; Wei, W. RSC Adv. 2014, 4, 47012. (12) Ruminski, A. M.; Jeon, K.-J.; Urban, J. J. J. Mater. Chem. 2011, 21, 11486. (13) Kim, T. K.; Lee, K. J.; Yuh, J.; Kwak, S. K.; Moon, H. R. New J. Chem. 2014, 38, S-16
1606. (14) Kim, T. K.; Lee, K. J.; Cheon, J. Y.; Lee, J. H.; Joo, S. H.; Moon, H. R. J. Am. Chem. Soc. 2013, 135, 8940. (15) Jiao, X.; Li, L.; Zhao, N.; Xiao, F.; Wei, W. Energy & Fuels 2013, 27, 5407. (16) Li, L.; Wen, X.; Fu, X.; Wang, F.; Zhao, N.; Xiao, F.; Wei, W.; Sun, Y. Energy & Fuels 2010, 24, 5773. S-17