Fei quanta 200 feg scanning electron microscope

A model of DXR smart Raman spectrometer (Thermo Fisher, Waltham, MA, USA) was used with a laser wavelength of 633 nm and a power of 2.5 mW. A model of the F-7000 fluorescence spectrophotometer (Hitachi Co., Chiyoda-ku, Japan), a model of the TU-1901 double beam UV–vis spectrophotometer (Beijing Purkinje General Instrument Co., Ltd., Beijing, China), a model of FEI Quanta 200 FEG scanning electron microscope (FEI Co., Ltd., Eindhoven, Holland), and a model of SK8200LH ultrasonic reactor (Shanghai Kudos Ultrasonic Instrument Co., Ltd., Shanghai, China) were used.

The morphology of the prepared samples was analyzed by FEI Quanta 200 FEG Scanning Electron Microscope (SEM) (FEI Company, Hillsboro, OR, USA) at an accelerating voltage of 5–10 kV. Prior to the SEM analysis, the cryogels were sputtered with gold (~7 nm). The bulk density of the samples was calculated as the mass-to-volume ratio, and the presented results are an average of three measurements. The specific surface area was analyzed by nitrogen adsorption-desorption test (Nova 3000e surface area analyzer, Quantachrome Instruments, Bointon Beach, FL, USA) and mercury porosimetry test (Carlo Erba Porosimeter 2000 equipped with the software Milestone 200, Carlo Erba, Washington, DC, USA). Before the measurements, the samples were degassed at 75 °C for 24 h. The presented results are the average values of 3 measurements; the standard deviation was within 10%.