1：Experimental Design and Method Selection:

The study uses a sol-gel reaction method based on Suzuki's report with modifications to synthesize VO2 nanoparticles on hollow silica nanoparticles. The hollow silica nanoparticles are prepared using a template method with polyacrylic acid aggregates. The vanadium precursor is vanadium iso-propoxide, which is refluxed with solvents and acetic acid to form a chelate compound, followed by hydrolysis with water. The crystallization is done under a nitrogen atmosphere to prevent oxidation.

2：Sample Selection and Data Sources:

Hollow silica nanoparticles are synthesized as described, and dense silica nanoparticles are used as a reference. Commercial VO2 particles from Strem Chemicals, Inc. are used for comparison.

3：List of Experimental Equipment and Materials:

Hollow silica nanoparticles, vanadium iso-propoxide (Kanto Chemical), iso-propanol, 2-methoxyethanol (FUJIFILM Wako Pure Chemical Corporation), acetic acid (FUJIFILM Wako Pure Chemical Corporation), 1-butanol, distilled water, polyacrylic acid (PAA, molecular weight 5,000), sodium chloride, ammonia solution, tetraethoxysilane (TEOS, FUJIFILM Wako Pure Chemical Corporation). Equipment includes helium gas pycnometer (ULTRAPYCNOMETER, Quantachrome Instruments), nitrogen gas adsorption analyzer (BEL-Sorp max, BEL Japan, Inc.), scanning electron microscope (JSM-7600F, JEOL Ltd.), transmission electron microscope (JEM-2000FX, JEOL Ltd.), X-ray diffractometer (MiniFlex 600, RIGAKU Corporation), UV-Vis spectrophotometer (UV1800, Shimadzu Corporation).

4：Experimental Procedures and Operational Workflow:

Hollow silica nanoparticles are prepared by dissolving PAA in a mixture of NaCl and ammonia, adding to ethanol, adding TEOS, stirring, adding water to remove template, and drying. For VO2 synthesis, vanadium iso-propoxide is refluxed with iso-propanol and 2-methoxyethanol under nitrogen, acetic acid is added, refluxed again, then added to hollow silica/1-butanol suspension with water, stirred, centrifuged, dried, heated in air at 200°C, and annealed in nitrogen at 600°C. Characterization involves SEM, TEM, XRD, UV-Vis, and gas adsorption analysis.

5：Data Analysis Methods:

XRD for crystallinity, SEM and TEM for morphology and particle size, EDS for elemental analysis, BET equation for specific surface area and pore size from nitrogen adsorption isotherms, UV-Vis for transmittance and thermochromic properties.