1：Experimental Design and Method Selection:

The study used flame spray pyrolysis (FSP) to synthesize Au-TiO2 nanoparticles in a single step, aiming to produce pure and small nanoparticles for improved photocatalytic activity. The methodology included characterization techniques such as XRD, HRTEM, and UV-Vis spectroscopy to analyze the structure and properties of the nanoparticles.

2：Sample Selection and Data Sources:

Precursor solutions were prepared using titanium isopropoxide and gold(III) chloride dissolved in xylene and ethanol, with Au loading concentrations set at 0.25%, 0.50%, 1.00%, and 2.00% mol%. The samples were synthesized and characterized, and photocatalytic activity was tested using methylene blue (MB) solutions.

3：25%, 50%, 00%, and 00% mol%. The samples were synthesized and characterized, and photocatalytic activity was tested using methylene blue (MB) solutions. List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: Equipment included a syringe pump, FSP reactor, X-ray diffractometer (XRD), high-resolution transmission electron microscope (HRTEM), UV-Vis spectrophotometer (PG Instruments T90), UVA lamp (Sylvania blacklight, 20 W), Millipore filter (0.22 μm), and glass reactor. Materials included titanium isopropoxide (Aldrich, 97%), gold(III) chloride (Electron Microscopy Science, 49+%), xylene (Carlo Erba, 98.5%), ethanol (Merck, 99.9%), and methylene blue.

4：22 μm), and glass reactor. Materials included titanium isopropoxide (Aldrich, 97%), gold(III) chloride (Electron Microscopy Science, 49+%), xylene (Carlo Erba, 5%), ethanol (Merck, 9%), and methylene blue. Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: The precursor was fed into the FSP reactor at 5 ml/min with O2 dispersion. Gas flow rates for methane and O2 were controlled. Nanoparticles were characterized. For photocatalytic testing, suspensions of TiO2 and Au-TiO2 NPs (0.6 g/L) were prepared in 20 ppm MB solution, stirred in darkness for 30 min to reach adsorption/desorption equilibrium, then irradiated with a UVA lamp. Samples were taken at intervals, filtered, and MB concentration was measured by absorbance at 665 nm using a UV-Vis spectrophotometer.

5：6 g/L) were prepared in 20 ppm MB solution, stirred in darkness for 30 min to reach adsorption/desorption equilibrium, then irradiated with a UVA lamp. Samples were taken at intervals, filtered, and MB concentration was measured by absorbance at 665 nm using a UV-Vis spectrophotometer. Data Analysis Methods:

5. Data Analysis Methods: Data from XRD, HRTEM, and UV-Vis spectroscopy were analyzed to determine phase structures, particle sizes, and absorption spectra. Photocatalytic degradation rates were calculated based on changes in MB concentration over time, with statistical analysis implied from the degradation percentages reported.