1：Experimental Design and Method Selection:

The study used submerged glow-discharge plasma for nanoparticle synthesis, chosen for its simplicity, control over size, high yield, and use of metal wires. The photocatalytic activity was evaluated using methylene blue decomposition under UV light.

2：Sample Selection and Data Sources:

Stainless steel SUS316L wire was used as the cathode, platinum mesh as the anode, and potassium carbonate solution as the electrolyte. Nanoballs were synthesized and characterized.

3：List of Experimental Equipment and Materials:

Equipment included a DC power supply (Takasago GP0250-10R), SEM-EDS (JEOL JSM7001FA FE-SEM), TEM (H-700 and TitanG3 60–300 S/TEM), XRD (Rigaku Miniflex), BET (Quantachrome Instruments Autosorb 6), UV/VIS spectrophotometer (Jasco V-630), and others. Materials included SUS316L wire, platinum wire, K2CO3 electrolyte, methylene blue, and PNDA.

4：Experimental Procedures and Operational Workflow:

The electrolyte was heated to 90°C, and a constant voltage of 130 V was applied for 3 hours to form nanoballs. After synthesis, nanoballs were centrifuged, washed, freeze-dried, and analyzed. Photocatalytic tests involved mixing nanoballs with MB or PNDA, irradiating with UV light (354 nm, 100 W) for up to 72 hours, and measuring absorbance.

5：Data Analysis Methods:

Data were analyzed using SEM-EDS for elemental composition, TEM for morphology and size, XRD for crystal structure, BET for surface area, and UV/VIS spectrometry for photocatalytic activity. Software like Mac-View ver.4 was used for size distribution.