1：Experimental Design and Method Selection:

The study involved synthesizing graphene oxide (GO) via the modified Hummer's method, reducing it to r-GO using hydrazine monohydrate, and functionalizing with silica-coated gold nanoparticles (Au-NPs) to form r-GO:Au-NPs nanocomposites. Techniques included XRD and TEM for structural analysis, Raman spectroscopy, XANES, XPS, and UPS for electronic structure, and I-V characteristics and SQUID magnetometry for electrical and magnetic properties.

2：Sample Selection and Data Sources:

Samples included r-GO and r-GO:Au-NPs nanocomposites with varying Au-NPs concentrations (e.g., 0.11 at.%, 0.22 at.%, 4.88 at.%). Data were sourced from laboratory syntheses and measurements at facilities like NSRRC (Taiwan) and UNISA (South Africa).

3：11 at.%, 22 at.%, 88 at.%). Data were sourced from laboratory syntheses and measurements at facilities like NSRRC (Taiwan) and UNISA (South Africa). List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: Equipment included Rigaku Smart-lab XRD, FEI Tecnai G2 F20 TEM, KRATOS-SUPRA XPS/UPS, HORIBA Scientific XploRA Raman spectrometer, SQUID magnetometer, and Keithley pico-voltage source meter. Materials included graphite powder, sodium nitrate, sulfuric acid, KMnO4, H2O2, hydrazine monohydrate, AuCl3, (3-mercaptopropyl) trimethoxysilane, tetrabutylammonium borohydride, and 3-(2-aminoethylamino) propyldimethoxymethylsilane.

4：Experimental Procedures and Operational Workflow:

GO synthesis involved mixing graphite with NaNO3 and H2SO4, adding KMnO4, then H2O2, followed by washing and sonication. r-GO was prepared by adding hydrazine to GO and heating. Au-NPs were synthesized by reacting AuCl3 with silanes and reducing agents, then mixed with GO and hydrazine to form composites. Characterization steps included XRD, TEM, Raman, XANES, XPS, UPS, I-V, and M-H measurements under specified conditions (e.g., pressures, temperatures).

5：Data Analysis Methods:

Data analysis involved calculating Au-NPs size using Debye-Scherer equation, ID/IG ratios from Raman spectra, π* intensity from XANES, elemental composition from XPS, deconvolution of XPS and UPS peaks, and interpretation of I-V and M-H curves for conductivity and magnetization.