Escalab220i xl spectrometer

The glass vessel containing the emulsion above was immersed in water bath of 70 °C for 12 h. Then the vessel was cooled to room temperature naturally and the floating gel was immersed in deionized water for 24 h to remove residual reducing agent. The graphene gel was directly frozen at −20 °C for 12 h and the two liquids were removed simultaneously by freeze drying to obtain aerogel. The morphologies of the as-synthesized aerogel were characterized by SEM (HITACHI S-4800) and TEM (JEOL-1010) operated at 100 kV. AFM measurements were performed on a tapping-mode atomic force microscope (Nanoscope IIIa, Digital Instruments, Santa Barbara, CA), with a silicon cantilever probes. XRD was performed on a Rigaku D/max-2500 diffractometer with Cu Kα radiation (λ = 1.5418 Å) at 40 kV and 200 mA. UV-visible spectrum was determined using a Varian Cary 1E UV-vis spectrophotometer. XPS was determined by VG Scientific ESCALab220i-XL spectrometer using Al Ka radiation. The porosities were determined by mercury intrusion porosimetry using a Micromeritics Autopore IV 9500 porosimeter. The sample was subjected to a pressure cycle starting at 5 psia, increasing to 44500 psia in predefined steps to give pore size/pore volume information. The compression test was carried out using a model 3342 Instron Universal Testing Machine at a rate of 50% strain min⁻¹.

The surface and morphology were visualized using electron microscopy facility (JEOL FE-2010 high-resolution microscope operated at 200 kV). The Raman spectra were recorded with a Renishaw inVia unit using the Ar ion laser with an excitation wavelength of 514.5 nm. X-ray photoelectron spectroscopy (XPS) analysis was studied using a VG Scientific ESCALAB 220 iXL spectrometer with an Al Kα (hv = 1486.69 eV) X-ray source. Nitrogen adsorption and desorption isotherms were measured at 77 K using Micromeritics ASAP 2010 Analyzer (USA) to obtain the Brunauer-Emmett-Teller (BET) surface area and pore size distribution.