1：Experimental Design and Method Selection:

Nebulized spray pyrolysis technique was used to deposit pristine and Cr-doped Co3O4 thin films on glass and FTO substrates. The method was chosen for its simplicity, control over droplet size, and cost-effectiveness.

2：Sample Selection and Data Sources:

Films were prepared with 0, 4, 6, and 8 at.% Cr doping concentrations. Substrates were cleaned by boiling in chromic acid, soap solution, and ultrasonication in acetone and distilled water.

3：List of Experimental Equipment and Materials:

Nebulizer spray setup, Co(NO3)2·6H2O, Cr(NO3)2·9H2O, double-distilled water, glass and FTO substrates. Equipment included PANalytical Xpert Pro diffractometer, HORIBA LabRAM HR spectrometer, Carl Zeiss Ultra SEM, Kratos Axis Ultra DLD XPS, Keithley 2400 SMU for four-probe method, AnTech-7000 UV-Visible spectrophotometer, CH Instrument CHI604D electrochemical workstation, Thermo Scientific UV-Visible spectrometer.

4：Experimental Procedures and Operational Workflow:

Precursor solutions were prepared, sprayed onto preheated substrates at 400°C with optimized parameters (spray volume 35 mL, carrier gas pressure

5：1 kg/cm2, substrate to nozzle distance 5 cm). Films were characterized structurally, morphologically, optically, and electrically. Electrochromic properties were measured in a three-electrode setup with 5 M NaOH electrolyte. Data Analysis Methods:

XRD for crystallite size and lattice parameters using Debye Scherrer's relation, Raman for vibrational modes, SEM for morphology, EDS and XPS for composition, four-probe for resistivity, UV-Vis for optical properties, cyclic voltammetry, chronocoulometry, chronoamperometry, and electrochemical impedance spectroscopy for electrochromic performance.