Jem f200

The crystalline structure was characterized by powder X-ray diffraction (PXRD; DMAX-2500PC). The micromorphology was obtained by using the field-emission scanning electron microscopy (FE-SEM; Hitachi Model SU-70) coupled with an energy-dispersive X-ray spectroscopy (EDS; X-max), and the high-resolution transmission electron microscopy (HR-TEM; JEM-F200). The contents of carbon were evaluated by thermogravimetric analysis (TGA; HCT-1). The Raman spectra were obtained through a Raman spectrometer (Horiba LabRAM HR). N₂ absorption–desorption isotherms were recorded by a chemisorption analyzer (Quantachrome Autosorb IQ). The specific surface area and pore-size distribution were calculated by the Brunauer–Emmett–Teller model and Barrett–Joyner–Halenda method, respectively. The surface electronic properties were investigated by X-ray photoelectron spectroscopy (XPS; Thermo ESCALAB 250XI). The Fourier transform infrared (FT-IR) spectra were recorded by a FT-IR spectrometer (VERTEX-70). The conductive properties were recorded by Hall Effect Measurement System (Ecopia HMS-5000). The electromagnetic parameters in the 2.0 − 18.0 GHz were measured by a vector network analyzer (VNA; Agilent PNA N5244A).

The morphology of the samples was characterized by field-emission scanning electron microscopy (SEM, SU-70, Hitachi) with accelerating voltages of 5 kV equipped with energy dispersive X-ray spectroscopy (EDS) and high-resolution transmission scanning electron microscopy (HRTEM JEM-F200) with an accelerating voltage of 200 kV equipped with EDS. The phase of catalysts was determined by the SmartLab X-ray diffraction (XRD) with Cu Kα radiation in the range of 2θ from 20° to 80° with step size of 0.01° at a scanning speed of 5° min⁻¹. X-ray photoelectron spectroscopy (XPS) was conducted on a Thermo Scientific™ K-Alpha™⁺ spectrometer equipped with a monochromatic Al Kα X-ray source (1486.6 eV) operating at 100 W. All peaks were calibrated with C1s peak binding energy at 284.8 eV. Elemental analysis was carried out by inductively coupled plasma optical emission spectroscopy (ICP-OES, ICAP 7000 SERIES Thermo) with three replicates. The nitrogen adsorption/desorption isotherm and the room-temperature CO₂ adsorption isotherm were measured by a Micromeritics 3Flex equipment Tristar II gas adsorption analyzer. The Bi L-edge spectra were collected at the 06ID-1 hard X-ray microprobe beamline from Canadian Light Source.