Ultima 4 with cu kα radiation

The morphology was confirmed using a field emission scanning electron microscopy at 10 kV (Tescan Mira-3 FEG, Brno, Czech Republic) and transmission electron microscopy (FEI, Tecnai G2-20, Hillsboro, OR, USA). A particle size analyzer (Malvern, Zetasizer Nano-ZS, Worcestershire, United Kingdom) was used to determine the silica particle size and zeta potential. The FT-IR spectra were recorded on Alpha-P (Bruker, Ettlingen, Germany). The XRD patterns were collected using an Ultima IV with Cu Kα radiation (Rigaku, Tokyo, Japan). The BET analyses were performed with an ASAP 2020 (Micromeritics, Gwinnett County, GA, USA) using the N2 adsorption–desorption isotherms. The pore size and distribution in the porous carbon was analyzed with an AutoPore IV 9500 mercury porosimeter at room temperature (Micromeritics, Gwinnett County, GA, USA). The XPS data were obtained using an Axis Nova (KRATOS, Tokyo, Japan) with monochromatic Al-Kα X-ray source under 10-8 Torr vacuum analysis chamber. The ICP-MS was used to analyze and confirm the cesium concentration in solution (iCAP RQ, Thermo Fisher Scientific, Waltham, MA, USA).

The morphology was confirmed using a Field Emission Scanning Electron Microscopy (FE-SEM) at 10 kV (Tescan Mira-3 FEG, Brno-Kohoutovice, Czech Republic). Fourier-transform infrared spectroscopy (FT-IR) spectra were recorded on Alpha-P (Bruker, Karlsruhe, Germany). X-ray diffraction (XRD) patterns were collected using a Ultima IV with Cu Kα radiation (Rigaku, Tokyo, Japan). The Thermogravimetric analysis (TGA) curves were performed from 25 to 1000 °C using a heating rate of 10 °C/min under N₂ atmosphere (SDT Q600, TA Instruments, New Castle, DE, USA). The Brunauer–Emmett–Teller (BET) analyses were performed with an ASAP 2020 (Micromeritics, Norcross, GA, USA) using the N₂ adsorption-desorption isotherms. The solutions were electrospun at room temperature using an electrospinning setup (ESR100D, NanoNC Co., Seoul, Korea). Inductively coupled plasma mass spectrometry (ICP-MS) was used to analyze and confirm the caesium concentration in solution (iCAP RQ, Thermo Fisher Scientific, Waltham, MA, USA).