Axis supra

X-ray photoelectron spectroscopy measurements were carried out
with an AXIS Supra by Kratos Analytical Inc. using monochromatized
Al Ka radiation (hv = 1486.6 eV, 225 W) as an X-ray
source with a base pressure of 10^–9 Torr. Survey
scan spectra were acquired using a pass energy of 160 eV and a 1 eV
step size. Narrow region scans were acquired using a pass energy of
40 eV and a 0.1 eV step size. The hybrid lens mode was used in both
cases. The analyzed area of all XPS spectra was 300 × 700 μm². A charge neutralizer was used throughout as the samples
were mounted such that they were electrically isolated from the sample
bar. All spectra were calibrated by C 1s (284.8 eV). This surface
was sputtered using the Ar-GCIS beam (n = 1000, 10
keV beam energy); the sputtering area is 3 × 3 mm². The etch rate was ∼30 nm/min for poly(lactic-co-glycolic
acid (PLGA, standard).

To plot the Tauc relation, the absorbance of a 100-nm-thick a-SVO film on a sapphire substrate was measured using a UV-visible spectrometer (UV-1800, Shimadzu) in the range of 200–900 nm. The crystal structure of the a-SVO was assessed with X-ray diffraction (XRD, SmartLab, Rigaku) in the range of 20–90° at a speed of 5°/min with a step size of 0.02°. A Cu target (λ = 1.5412 Å) was used as the X-ray source. The work function of the a-SVO was determined using UPS (AXIS SUPRA, Kratos). To investigate the conductive filament, ToF-SIMS (TOF.SIMS-5, ION-TOF, Münster, Germany) was used with a rastered Cs⁺ beam with an energy of 3 keV and a current of 30 nA (raster size: 300 μm × 300 μm).

To evaluate the chemical composition of the zirconia surface, X-ray photoelectron spectroscopy (XPS) (AXIS SUPRA, Kratos Analytical Ltd., UK) analysis was performed before and after NTP treatment. Of the 24 cube-shaped zirconia blocks, six were assigned per surface treatment group. The blocks were placed on carbon tape, and XPS data were acquired using a monochromatic Al-Kα X-ray source (1486.6 eV) at 15 kV and 225 W. All composition measurements were acquired at the surface normal with charge neutralization. The binding energy scale was calibrated using a C1s level of 284.5 eV. The angle between the X-ray source and the analyzer was 54.7°. A 165 mm mean radius hemispherical sector analyzer was used as an electron energy analyzer, operating in fixed analyzer transmission (FAT) mode. For each block, a compositional survey scan was acquired using a pass energy of 160 eV and core level spectra with a pass energy of 20 eV. The block was placed in a vacuum chamber of 5 × 10⁻⁹ Torr. Data analysis was performed using data reduction software (Vision 1.5, Kratos Analytical Ltd., Kratos Analytical Ltd., Manchester, UK). The deconvoluted spectra were fitted with a Gaussian−Lorentzian sum function (20% Gaussian and 80% Lorentzian) using the XPS peak fitting program provided by Raymund WM Kwok (XPS PEAK 4.1, The Chinese University of Hongkong, Shatin, Hong Kong).

The synthesized GO, RGO and β-CD-RGO were characterized via FT-IR spectroscopy (Bruker Alpha II, Billerica, MA, USA) and Raman spectroscopy (HORIBA XploRA, Kyoto, Japan) for structural and vibrational analysis. To obtain accurate ID/IG values, we first baseline-corrected the spectra by subtracting a linear fit to the background signal. We then used multi-peak fitting with Lorentzian peak shapes to deconvolve the distinct D and G bands. The peak positions were constrained based on expected wavenumbers, but the peak widths and intensities were allowed to vary during fitting. X-ray photoelectron spectroscopy (Kratos AXIS Supra, Manchester, UK) was used to analyze surface elemental composition and chemical states. Morphology was examined under field emission scanning electron microscopy (FESEM, ZEISS Sigma, White Plains, NY, USA).

XPS (Perkin-Elmer Corporation, MN, USA) was performed using a Kratos Axis Supra with aluminium k-alpha radiation (1486.7 eV). The spectrometer was operated in FAT mode. Survey scans were acquired using an analyser pass energy of 160 eV to ensure maximum sensitivity. High-resolution scans were performed with a pass energy of 20 eV to improve energy resolution at the expense of sensitivity. The instrument’s work function was calibrated to place the 4f 7/2 line of gold at a binding energy of 84.0 eV, and the instrument range was tuned to ensure the binding energy of the 2p 3/2 line of copper at 932.6. Charge compensation was performed using the in-built Kratos charge neutralizer, producing an offset of approximately −3 eV of binding energy, which was corrected by rigidly shifting all spectra to a known reference level.

Surface morphology and elemental composition were characterized by a TESCAN MIRA3 XMU SEM equipped with an Oxford Instruments energy dispersive X-ray (EDX) detector. The Brunauer–Emmett–Teller (BET) specific surface area was evaluated from the adsorption data registered through a 3P micro 300 instrument in the relative pressure (p/p₀) range of 0.1 ÷ 0.3. Before BET measurements, samples were degassed at 300 °C overnight^{44 (link)}. The crystalline structure was determined by XRD in parallel beam mode using a Rigaku SmartLab 9 kW diffractometer equipped with a high-brightness Cu K_α rotating anode X-ray tube operated at 45 kV and 150 mA. Surface chemical composition was studied by XPS using a Kratos Analytical Axis Supra instrument with a monochromatic Al K_α (1486.7 eV) excitation source. All spectra were calibrated to the adventitious C 1s peak at 284.8 eV and fitted using CasaXPS software. The magnetic hysteresis loop was measured using a Quantum Design VersaLab cryogen-free VSM at 300 K for an applied magnetic field ranging from −10 to 10 kOe at steps of 10 Oe s⁻¹. Light-absorption spectra were measured using a Jasco V-750 UV–Visible spectrophotometer equipped with an integrating sphere. Zeta potential measurements were performed in water at pH 7 and 3 using a Malvern Panalytical Zetasizer Ultra instrument.