1：Experimental Design and Method Selection:

The study used the electric field-assisted aqueous solution (EFAS) technique to synthesize flower-like ZnO nanostructures on porous Si (PSi) substrates without a seed layer. Electrochemical impedance spectroscopy (EIS) was employed to detect chemical solvents.

2：Sample Selection and Data Sources:

An n-type Si (100) substrate was used to form PSi via photoelectrochemical etching. Chemical solvents tested were ethanol, acetone, toluene, and benzene.

3：List of Experimental Equipment and Materials:

Equipment included a Keithley 220 programmable current source, atomic force microscopy (AFM; Dimension EDGE, BRUKER), field emission scanning electron microscopy (FESEM; FEI/Nova NanoSEM 450), x-ray diffraction (XRD; PANalytical X'Pert PRO MRD PW3040), photoluminescence and Raman spectroscopy (Jobin–Yvon HR 800 UV), and an impedance gain phase analyzer (EIS: Solartron-Si1287/Si1260). Materials included hydrofluoric acid, ethanol, zinc nitrate hexahydrate, hexamethylenetetramine, and deionized water.

4：0). Materials included hydrofluoric acid, ethanol, zinc nitrate hexahydrate, hexamethylenetetramine, and deionized water. Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: PSi was formed by etching Si in HF/ethanol solution at 20 mA/cm2 for 8 min under illumination. ZnO nanostructures were grown using EFAS with

5：025 M zinc nitrate and hexamethylenetetramine at 5 mA/cm2 for 1 h at 105°C. EIS measurements were performed in frequency range 1 Hz to 32 MHz with 500 mV amplitude. Data Analysis Methods:

Data from EIS were analyzed using Nyquist plots and equivalent circuit models to determine resistance and capacitance parameters. Sensitivity was calculated based on impedance changes.