Supporting Information Surfactant-Free Assembly of Mesoporous Carbon Hollow Spheres with Large Tunable Pore Sizes Hongwei Zhang, Owen Noonan, Xiaodan Huang, Yannan Yang, Chun Xu, Liang Zhou, and Chengzhong Yu * Figure S1 X-ray photoelectron spectroscopy (XPS) analysis of SiO 2 @SiO 2 /C composite and MCHS. 1
Figure S2 Tyndall effect (a) and DLS analysis (b) of MCHS aqueous solution. 2
Figure S3 Nitrogen sorption (a) and pore size distribution (b) of MCHS and MCHS-TEOS. Additional discussion: Nitrogen sorption analysis is an efficient technique to determine the specific surface area, pore volume, and pore size distribution as well as to study the surface properties of porous materials. According to the shape, the nitrogen sorption isotherms can be classified into six types. The experimental nitrogen sorption isotherms of mesoporous materials usually fall into type-iv isotherm, in which a hysteresis at high relative pressure is observed because capillary condensation and capillary evaporation of nitrogen often do not take place at the same pressure. Barrett Joyner Halenda (BJH) pore size distribution is a commonly used method to calculate the pore size of porous materials. This method is based on the general concept of an algorithm outlined in the BJH work. 1 More detailed information about nitrogen sorption analysis can be found in literatures. 2 3
Figure S4 SEM images (a and b) of SiO 2 @ SiO 2 /C composite (prepared from TEOS and RF precursors) after carbonization under N 2 atmosphere, TEM image (c) of silica template after removing carbon by calcination in air, SEM (d and e) and TEM (f) images of MCHS-TEOS after removing silica templates by HF etching. 4
Figure S5 SEM and TEM images of MCHS-0.25 (a-c), MCHS-0.5 (d-f) and MCHS-0.75 (gi) 5
Figure S6 SEM images of SiO 2 @ SiO 2 /C composite and TEM images of silica templates for MCHS-0.25 (a-c), MCHS-0.5 (d-f) and MCHS-0.75 (g-i) 6
Figure S7 Nitrogen sorption (a) and pore size distribution (b) of MCHS-0.25, MCHS-0.5 and MCHS-0.75. 7
Figure S8 TEM image (a) and N 2 sorption analysis of large pore MCHS prepared with a ratio of EtOH: H 2 O at 3: 1. 8
Figure S9 TEM images of silica templates at various reaction time: 2 h (a), 3 h (b), 4 h (c), 6 h (d) and 9 h (e); TEM images of carbon products at various reaction time: 2 h (f), 3 h (g), 4 h (h), 6 h (i) and 9 h (j). Additional discussion: To further investigate the formation process of MCHS, we use TEM to characterize the samples of silica templates after calcination in air and carbon products obtained after carbonization and removal of silica cores at different reaction time. As shown in Figure S9, solid silica Stöber spheres have formed at 2 h, while only some carbon residues are seen from the carbonized product, probably due to the relative low cross-linking of RF layers at this time point. With the time increased to 4 h, silica particles with porous shells are observed. The hollow structures of carbon can be maintained after removing silica templates due to the increased cross-linking of RF component. With prolonged reaction time, the particle size of silica increases from 250 nm at 4 h to 300 nm at 9 h, while the thickness of porous shells increases from 20 nm to 45 nm. The carbon products also increase both in particle size and thickness of shells with increased reaction time, which are consistent with the observation from silica templates. 9
Figure S10 TGA analysis of SiO 2 @RF with different reaction time in air atmosphere. 10
Figure S11 Schematic illustration of the difference of choice of TEOS and TPOS as silica sources for MCHS. Step I: homogeneous nucleation of silica sources and initial polymerization of RF oligomers; step II: deposition of RF or SiO 2 /RF layers on the surface of silica core particles, forming SiO 2 @RF or SiO 2 @SiO 2 /RF core-shell structures; step III: carbonization and selective etching of silica templates. 11
Figure S12 Schematic illustration of a three-electrode configuration of supercapacitors. Working electrode: active material/conductive carbon/ptfe coating on a Ni form chip; reference electrode: Hg/HgO electrode; counter electrode: Ni form; and electrolyte: 6 M KOH. 12
Figure S13 Electrochemical performances of MCHS-0.25, 0.5, and 0.75 at various current densities. 13
Figure S14 TEM images of MnO 2 nanowires (a) and spindle-like Fe 2 O 3 nanoparticles (b). 14
Table S1 Surface area, pore volume, and particle size distribution of MCHSs. Surface area Pore volume Meso pore volume Samples (m² g -1 ) (cm³ g -1 ) (cm³ g -1 ) Particle size distribution* MCHS-TEOS 977 1.45 0.21 194±6 MCHS-0.25 897 2.0 0.35 212±7 MCHS-0.5 1251 2.31 0.6 228±7 MCHS-0.75 1387 2.04 0.81 261±8 MCHS 1582 2.45 1.05 323±10 *Note: The format a ± b indicates the average and standard deviation of particle size based on at least 50 manual measurements from TEM images. Table S2 TGA analysis of SiO 2 /RF with different reaction time. Samples Weight retention (%) RF percentage (%) Pure silica 88.5 -- Silica/RF 2 h 88.0 0.5 Silica/RF 3 h 86.7 1.8 Silica/RF 4 h 82.1 6.4 Silica/RF 6 h 75.8 12.7 Silica/RF 9 h 71.2 17.3 15
Table S3 Specific capacitances and capacitance retention of MCHSs with different pore sizes. Samples 1 A g -1 50 A g -1 Capacitance retention MCHS-TEOS 202.5 82.3 40.6 % MCHS-0.25 288.4 124 43 % MCHS-0.5 291.5 135 46 % MCHS-0.75 301.5 145 48 % MCHS 310.4 157 50.6 % 16
Table S4 Comparison of the electrochemical performance of porous Carbon based nanomaterials in aqueous electrolytes for EDLCs. Materials Electrolytes Specific capacitance (F g -1 ) at corresponding currents References N-doped porous nanofibers 6 M KOH 202 at 1 A g -1 3 N-doped ordered mesoporous carbon 6 M KOH 227 at 0.2 A g -1 4 N-doped carbon nanocages 6 M KOH 313 at 1 A g -1 5 N-doped ordered mesoporous carbon Honeycomb-like porous carbon Ultrahigh-surface-area hollow carbon nanospheres N-doped ordered mesoporous carbon single crystals N-doped porous carbon capsules Bamboo-like carbon nanofiber 6 M KOH 230 at 0.5 A g -1 6 6 M KOH 342 at 0.2 A g -1 7 6 M KOH 203 at 0.1 A g -1 8 6 M KOH 281at 0.5 A g -1 9 1 M H 2 SO 4 240 at 0.1 A g -1 10 3 M KOH 236 at 5 A g -1 11 MCHS 6 M KOH 310 at 1 A g -1 This work References 1. Barrett, E. P.; Joyner, L. G.; Halenda, P. P. The Determination of Pore Volume and Area Distributions in Porous Substances. I. Computations from Nitrogen Isotherms, J. Am. Chem. Soc. 1951, 73, 373-380. 2. Kruk, M.; Jaroniec, M. Gas Adsorption Characterization of Ordered Organic Inorganic Nanocomposite Materials, Chem. Mater. 2001, 13, 3169-3183. 3. Chen, L. F.; Zhang, X. D.; Liang, H. W.; Kong, M. G.; Guan, Q. F.; Chen, P.; Wu, Z. Y.; Yu, S. H. Synthesis of Nitrogen-Doped Porous Carbon Nanofibers as an Efficient Electrode Material for Supercapacitors. ACS Nano 2012, 6, 7092-7102. 4. Wei, J.; Zhou, D. D.; Sun, Z. K.; Deng, Y. H.; Xia, Y. Y.; Zhao, D. Y. A Controllable Synthesis of Rich Nitrogen-Doped Ordered Mesoporous Carbon for CO 2 Capture and Supercapacitors. Adv. Funct. Mater. 2013, 23, 2322-2328. 17
5. Zhao, J.; Lai, H. W.; Lyu, Z. Y.; Jiang, Y. F.; Xie, K.; Wang, X. Z.; Wu, Q.; Yang, L. J.; Jin, Z.; Ma, Y. W.; Liu, J.; Hu, Z. Hydrophilic Hierarchical Nitrogen-Doped Carbon Nanocages for Ultrahigh Supercapacitive Performance. Adv. Mater. 2015, 27, 3541-3545. 6. Shi, Q.; Zhang, R. Y.; Lu, Y. Y.; Deng, Y. H.; Elzatahrya, A. A.; Zhao, D. Y. Nitrogen-Doped Ordered Mesoporous Carbons Based on Cyanamide as the Dopant for Supercapacitor. Carbon 2015, 84, 335-346. 7. Liang, Q. H.; Ye, L.; Huang, Z. H.; Xu, Q.; Bai, Y.; Kang, F. Y.; Yang, Q. H. A Honeycomb-Like Porous Carbon Derived from Pomelo Peel for Use in High-Performance Supercapacitors. Nanoscale 2014, 6, 13831-13837. 8. Xu, F.; Tang, Z. W.; Huang, S. Q.; Chen, L. Y.; Liang, Y. R.; Mai, W. C.; Zhong, H.; Fu, R. W.; Wu, D. C. Facile Synthesis of Ultrahigh-Surface-Area Hollow Carbon Nanospheres for Enhanced Adsorption and Energy Storage. Nat. Commun. 2015, 6, 7221. 9. Shen, G. Z.; Sun, X. R.; Zhang, H. W.; Liu, Y.; Zhang, J.; Meka, A.; Zhou, L.; Yu, C. Z. Nitrogen-Doped Ordered Mesoporous Carbon Single Crystals: Aqueous Organic-Organic Self-Assembly and Superior Supercapacitor Performance. J. Mater. Chem. A 2015, 3, 24041-24048. 10. Ferrero, G. A.; Fuertes, A. B.; Sevilla, M. N-Doped Porous Carbon Capsules with Tunable Porosity for High-Performance Supercapacitors. J. Mater. Chem. A 2015, 3, 2914-2923. 11. Sun, Y. M.; Sills, R. B.; Hu, X. L.; Seh, Z. W.; Xiao, X.; Xui, H. H.; Luo, W.; Jin, H. Y.; Xin, Y.; Li, T. Q.; Zhang, Z. L.; Zhou, J.; Cai, W.; Huang, Y. H.; Cui, Y. A Bamboo- Inspired Nanostructure Design for Flexible, Foldable, and Twistable Energy Storage Devices. Nano Lett. 2015, 15, 3899-3906. 18