Jem 2010

Brunauer–Emmett–Teller (BET) surface area data were collected by obtaining nitrogen adsorption isotherms at 77 K using a Micromeritics ASAP 2020 analyser (ASAP 2020, Micromeritics Company, USA). Wide-angle XRD patterns (10°–90° over 2 h) were collected using a Bruker D8 Advanced X-ray diffractometer with Cu Kα radiation (k = 1.5406 Å) at 40 kV and 40 mA (Bruker D8, Brucker Company, Germany). TEM images were acquired with a JEM 2010 electron microscope at an accelerating voltage of 200 kV to examine sample morphologies (JEM-2010, JEOL Company, Japan), and field emission scanning electron microscope (S-4800, Hitachi Company, Japan). XPS data were generated using an Axis Ultra spectrometer with monochromatized Al Kα X-ray radiation as the excitation source (225 W) (EscaLab 250Xi, Thermo Fisher Scientific Company, USA). Raman microspectroscopy was performed with a Renishaw InVia unit having an Ar ion laser (inVia reflex, Renishaw Company, UK). TGA data were acquired using a TA instrument, operating under air at a flow rate of 100 mL min⁻¹. The temperature of each sample was increased from 30 to 800 °C at a heating rate of 10 °C min⁻¹ (SDT Q600, TA Company, USA). TPD trials were carried out with a Micromeritics ASAP 2720 instrument with a temperature ramp of 40–650 °C, a ramp rate of 10 °C min⁻¹ and a flow of 45 mL min⁻¹ (ASAP 2720, Micromeritics Company, USA).

SWCNTs synthesized by the chemical vapor deposition method (Sigma-Aldrich, Inc.) were used in this study. Their physical and chemical properties were characterized by several techniques, including Raman spectroscopy, SEM, and TEM. Raman spectra were collected using a Raman microscope (Renishaw inVia Plus, Renishaw Inc., Hoffman Estates, IL, USA) with a 50× air objective lens and a 633 nm (1.96 eV) laser. Diameters and shapes of SWCNTs were characterized using SEM and TEM (JEOL-6700F and JEOL JEM-2010, respectively, JEOL Ltd., Tokyo, Japan).

XRD was carried out using a X’Pert powder X-ray diffractometer with Cu K_α radiation (λ = 0.15418 nm). Raman spectra were obtained using laser confocal micro-Raman spectroscopy (LabRAM HR800, Horiba Jobin Yvon). FTIR spectra were collected using a Tensor27 (Bruker) spectrometer. XPS measurements were performed in an ESCALAB 250 spectrometer under vacuum (about 2 × 10⁻⁹ mbar). Field-emission SEM images were conducted on a Quanta 400 FEG microscope (FEI Company). TEM images corresponding element energy-dispersive X-ray spectrometer (EDS) were carried out on a JEOL JEM-2010 (JEOL Ltd.). All electrochemical measurements were tested in a three-electrode cell using a CHI 760e electrochemical work station at 25 °C. Solutions were freshly prepared before each experiment. A platinum foil (3.0 cm²) was used as counter electrode. All the potentials were measured versus a saturated calomel electrode (SCE, 0.241 V vs. NHE) electrode. CV data were recorded between −0.95 to 0.40 V with a scan rate at 50 mV s⁻¹.

Investigation of nano-filler dispersion in the NR nanocomposite samples was carried out by using transmission electron microscopy (TEM) (JEOL JEM 2010, JEOL Co., Tokyo, Japan). The ultra-thin section (ca., 100 nm) was cut with a diamond knife at a temperature of −120 °C by using an ultramicrotome (RMC MT-XL, RMC Products Group, Ventana Medical System, Inc., Oro Valley, AZ, USA).

With Cu KR radiation (0.15406 nm), the X-ray diffraction (XRD) spectra were recorded on a D/MAX-2500 diffraction meter. The operation voltage was maintained at 40 kV and 200 mA.
The transmission electron microscope images (TEM) were taken with a JEOL-JEM2010 operating at 200 kV (JEOL, Tokyo, Japan). Dropping a diluted dispersion of MoO₃-NPs over a conventional carbon-coated (20–30 nm) sheet on a copper grid produced TEM samples.
Scanning electron microscopy (SEM; JEOL, Tokyo, Japan) was used for obtaining surface images equipped with energy-dispersive X-ray fluorescence analysis (EDX) that was used to investigate the morphology of samples. The product was applied over the silicon substrate for SEM inspection.
Fourier transformation infrared spectroscopy (FT-IR) was acquired with an FT-IR spectrometer. The FT-IR spectra of MoO₃-NPs were studied on pellets made by combining the nanoparticles with KBr at around a 1:50 volume ratio.
The UV-visible absorption spectroscopic measurements were performed on a HITACHI U-4100 spectrophotometer using a quartz cell with a width of 1 cm.
Zeta potential measurements is a technique for the assessment of the particle’s surface charge in the solution; this technique is directly related to the stability of MoO₃-NPs suspension.