of the prepared sample
was analyzed by field-emission scanning electron microscopy (FESEM,
Hitachi S-4800 and Zeiss Merlin compact) and field-emission transmission
electronic microscopy (FETEM) (JEOL-2100F, JEOL Ltd., Japan). Elemental
distribution maps were collected by energy-dispersive spectrometry
(EDS, Bruker Xflash 6100) using an accelerating voltage of 15 kV.
Powder X-ray diffraction (PXRD) was performed using an X-Pert3 powder
(PANalytical, the Netherlands) diffractometer with Cu Kα1 (λ
= 1.5406 Å) radiation. X-ray photoelectron spectroscopy (XPS,
Al Kα radiation, and hν = 1486.6 eV)
was performed to reveal the chemical compositions and valence state
using the C 1s peak of the C–C and C–H bonds located
at 284.8 eV as reference. The CasaXPS software was adapted to conduct
the peak fitting. Thermogravimetric–mass spectrometric (TG-MS)
analysis was carried out using an STA449C/Qms 403C. The Raman spectra
of the prepared catalysts were collected with Jobin Yvon-Horiba LabRam
ARAMIS systems with 532 nm excitation lasers. A Micromeritics ASAP2020
device (at 77 K) was employed to perform the N2 adsorption–desorption
test. Infrared (IR) spectra were collected using a Fourier transform
infrared spectrometer (Nicolet is50, ThermoFisher Co.).