images were taken at an acceleration voltage of 5 keV and a working
distance of 15 mm using a JEOL JSM-7500F instrument. Transmission
electron microscopy (TEM) analysis was conducted using an FEI Tecnai
G2 F20 Super-Twin FE-TEM instrument operating at 120 kV. TEM samples
were prepared using a Tescan LYRA-3 Model GMH dual-beam FIB instrument.
X-ray diffraction (XRD) patterns were collected using a Miniflex II
diffractometer (Rigaku) with Cu Kα radiation (λ = 1.5406
Å) in the 2θ range of 5–40°. A Nicolet iS5
spectrophotometer equipped with iD7 ATR (Thermo Scientific) was used
to obtain attenuated total reflectance Fourier transform infrared
(ATR-FTIR) spectra at a resolution of 5 cm–1 with
16 scans in the span of 4000–400 cm–1. Thermogravimetric
analysis (TGA) was performed using a Q50 apparatus (TA Instruments)
in the temperature range of 25–800 °C at the heating rate
of 10 °C min–1 under an air flow of 60 cm3 min–1. N2 adsorption isotherms
were taken using an ASAP 2020 plus instrument (Micromeritics) at 77
K.