1：Experimental Design and Method Selection:

The study uses an improved chemical vapor deposition (CVD) system with a cold wall reactor to synthesize graphene-encapsulated copper particles (GCPs). The method involves using gaseous carbon sources (methane) and solid carbon sources (sodium citrate) to deposit graphene on spherical Cu particles at a lower temperature (775°C) to prevent agglomeration.

2：Sample Selection and Data Sources:

Sodium citrate-coated Cu particles with diameters ranging from 200 nm to 550 nm and purity of

3：9% were purchased from Aladdin Shanghai Biological Technology Co., Ltd. List of Experimental Equipment and Materials:

Cold wall CVD reactor, Cu particles, methane gas, hydrogen gas, argon gas, sodium citrate, field emission scanning electron microscopy (SEM, ZEISS Merlin Compact), Raman Spectrometer (INVIA), X-ray Diffraction (XRD, 3 KW D/MAX2200 V PC), transmission electron microscopy (TEM, FEI Tecnai G2 F20 S-TWIN), thermogravimetric differential analyzer (Mettler Toledo), Xenon NanoFlash (NETZSCH LFA 447).

4：7). Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: Cu particles were placed in a Cu boat in the cold wall CVD reactor, heated to 775°C in hydrogen/argon atmosphere, annealed for 5 minutes, then methane was introduced for graphene growth. After growth, the chamber was cooled, and particles were characterized using SEM, Raman, XRD, TEM, TG-DSC, and thermal conductivity measurements.

5：Data Analysis Methods:

Raman spectra were analyzed for graphene layer identification, TG-DSC for thermal stability, XRD for oxidation resistance, and thermal conductivity was measured using Xenon NanoFlash.