1：Experimental Design and Method Selection:

The study used an electrospinning method to synthesize 1D and porous Nb2O5-TiO2 n-n junction nanofibers with different Nb molar ratios (0 mol%, 3 mol%, 6 mol%, 9 mol%). The rationale was to leverage electrostatic interactions to create nanofibers with enhanced surface area and heterojunctions for improved gas sensing. Theoretical models include the adsorption-reaction mechanism for gas sensing and Scherrer equation for grain size calculation.

2：Sample Selection and Data Sources:

Samples were prepared using precursor solutions with titanium isopropoxide, polyvinylpyrrolidone (PVP), acetic acid, ethanol, and niobium(V) ethoxide. Selection criteria were based on Nb concentration variations to optimize sensing properties.

3：List of Experimental Equipment and Materials:

Equipment includes an electrospinning setup (inoculator, high voltage source), calcination furnace, X-ray diffractometer (Bruker D8 Advance), field emission scanning electron microscope (FE-SEM: Nova Nano-SEM450), field emission transmission electron microscope (TEM: Tecnai G2 F20), X-ray photoelectron spectroscopy (XPS: VG Scientific with Mg K radiation), nitrogen adsorption analyzer (ASAP 2460), and intelligent gas sensing analysis system (CGS-4TPs, Beijing Elite Tech Co., Ltd). Materials include ethanol, acetic acid, PVP, niobium(V) ethoxide, titanium isopropoxide, and Ag-Pd electrodes.

4：Experimental Procedures and Operational Workflow:

Precursor solutions were stirred for 12 h, electrospun with specific parameters (18.0 kV high voltage, -4.0 kV low negative voltage, 1.5 mL/h flow rate, 200.0 r/min rotate speed, 15.0 cm distance), collected on aluminum foil, and calcined at 500 °C for 2 h. Sensors were fabricated by smearing slurry onto Ag-Pd electrodes, aged at 400 °C for 4 h, and tested in a static chamber with gas injection via syringe. Gas sensing measurements were conducted at temperatures from 175 °C to 375 °C with ethanol concentrations up to 500 ppm.

5：0 kV high voltage, -0 kV low negative voltage, 5 mL/h flow rate, 0 r/min rotate speed, 0 cm distance), collected on aluminum foil, and calcined at 500 °C for 2 h. Sensors were fabricated by smearing slurry onto Ag-Pd electrodes, aged at 400 °C for 4 h, and tested in a static chamber with gas injection via syringe. Gas sensing measurements were conducted at temperatures from 175 °C to 375 °C with ethanol concentrations up to 500 ppm. Data Analysis Methods:

5. Data Analysis Methods: Data analysis involved XRD for crystalline structure, SEM and TEM for morphology, XPS for chemical states, BET for surface area, and response calculations (Sg = Ra/Rg). Statistical techniques included Gaussian fitting for XPS peaks and linear regression for response-concentration relationships.