1：Experimental Design and Method Selection:

The method involves infrared imaging of Joule-heated graphene under electric current flow to visualize temperature non-uniformity caused by defects. Finite element method simulations were used to model Joule heating distribution.

2：Sample Selection and Data Sources:

Graphene monolayer grown on copper foil by CVD and transferred onto glass substrates of various sizes (25 mm × 25 mm to 40 mm × 100 mm, thickness 0.7–2.5 mm) with metallic contacts on opposite edges.

3：7–5 mm) with metallic contacts on opposite edges. List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: SEM Carl Zeiss Auriga cross beam workstation for surface quality verification; InSb 640 M camera (Thermosensorik/DCG Systems) with 1.1–4.9 μm detection range and optical filters, equipped with wide-field and microscopic lenses; FLIR T630sc camera with microbolometer detector (7.5–14 μm range); Peltier elements or heat sinks for cooling; glass substrates; DC power supply for polarization up to 200 V.

4：1–9 μm detection range and optical filters, equipped with wide-field and microscopic lenses; FLIR T630sc camera with microbolometer detector (5–14 μm range); Peltier elements or heat sinks for cooling; glass substrates; DC power supply for polarization up to 200 V. Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: Samples were DC polarized at various voltages; thermal images were recorded from the graphene side with and without cooling; temperature calibration using controlled temperature sample holder; differential imaging by subtracting reference images; intentional scratches made using ball-on-plane wear test.

5：Data Analysis Methods:

Finite element simulations using NETGEN 5.1 for mesh generation and ELMER FEM software for solving Maxwell's equations; thermal image analysis to identify hot spots and temperature profiles.