1：Experimental Design and Method Selection:

The study uses a resistance-heating quartz tube furnace to grow VGNs by heating solid precursor films (glucose and/or urea) coated on stainless steel substrates. The method is chosen for its simplicity, scalability, and cost-effectiveness compared to plasma-enhanced chemical vapor deposition (PECVD).

2：Sample Selection and Data Sources:

304 stainless steel plates are used as catalytic substrates. They are roughened using silicon carbide paper to create patterned regions for selective VGN growth. Precursor solutions are prepared by dissolving glucose, glucose + urea (1:1 weight ratio), or urea in deionized water.

3：List of Experimental Equipment and Materials:

Equipment includes a resistance-heating quartz tube furnace, spin-coater or brush for coating, oven for drying, ultrasonic cleaner, atomic force microscope (AFM, MultiMode with NanoScope controller), scanning electron microscope (SEM, MIR A3, TESCAN), transmission electron microscope (TEM, FEI Tecnai G2 F30), micro-Raman spectroscope (Jobin-Yvon Horiba HR800), X-ray photoelectron spectroscope (XPS, Kratos Axis Ultra DLD), and field emission measurement setup with Keithley 248 power source. Materials include 304 stainless steel, silicon carbide paper, acetone, ethyl alcohol, deionized water, glucose, urea, and argon gas.

4：Experimental Procedures and Operational Workflow:

Substrates are roughened and cleaned ultrasonically. Precursor solutions are spin-coated or brushed onto substrates and dried at 60°C. The coated substrates are placed in the furnace, pumped to 10^-1 Pa, filled with argon to 70 kPa, heated to 850°C at 5°C/min, and held for 30 minutes for VGN growth. Characterization involves AFM, SEM, TEM, Raman spectroscopy, XPS, and field emission measurements.

5：Data Analysis Methods:

Morphology and microstructure are analyzed using AFM, SEM, and TEM. Chemical composition is determined by XPS. Crystallinity and defects are assessed via Raman spectroscopy. Field emission properties are evaluated using J-E curves and Fowler-Nordheim plotting to calculate turn-on field and enhancement factor.