1：Experimental Design and Method Selection:

The study uses a one-step electrospinning technology combined with calcination to fabricate hierarchical WO3/ZnWO4 1D fibrous heterostructures. The method involves introducing ZIF-8 into the precursor solution to tune phase composition and morphology through nucleation competition and crystal planes matching mechanisms during heat treatment.

2：Sample Selection and Data Sources:

Samples include pure WO3 nanofibers, WO3/ZnWO4-5%, and WO3/ZnWO4-10% composites, synthesized with varying amounts of ZIF-8 (0.05 mmol and 0.1 mmol). ZIF-8 nanoparticles are synthesized separately and added to the electrospinning precursor.

3：05 mmol and 1 mmol). ZIF-8 nanoparticles are synthesized separately and added to the electrospinning precursor. List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: Equipment includes an electrostatic spinning machine (FM-1206, Beijing Future Material Sci-tech Co., Ltd), X-ray diffractometer (XRD, D8-ADVANCE, Bruker Corporation), field-emission scanning electron microscope (QUANTA 250 FEG, FEI, USA), transmission electron microscope (Tecnai F20, FEI), Raman spectrometer (LabRAM HR Evolution, HORIBA JOBIN YVON SAS), UV-Vis spectrometer (Hitachi U-4100), X-ray photoelectron spectrometer (ESCALAB 250), multifunction adsorption spectroscopy (MFA-140, Builder Company, Beijing), and gas sensing analysis system (CGS-4TPs, Beijing Elite Tech Co., Ltd, China). Materials include polyvinylpyrrolidone (PVP), tungstic acid, ammonia, ethanol, deionized water, Zn(NO3)2·6H2O, 2-methylimidazole, methanol, and commercial ceramic substrates with Ag-Pd interdigital electrodes.

4：Experimental Procedures and Operational Workflow:

For WO3 nanofibers, PVP is dissolved in ethanol and water, tungstic acid is dissolved in ammonia, mixed, electrospun at 18 kV with 18 cm tip-to-collector distance and 7 μL/min feed rate, and calcined at 600°C for 2 h. ZIF-8 is synthesized by dissolving Zn(NO3)2·6H2O and 2-methylimidazole in methanol, stirring, standing, washing, and drying. For WO3/ZnWO4 composites, ZIF-8 is dispersed in ethanol and added to the precursor solution before electrospinning and calcination. Gas sensing measurements involve coating samples on substrates, drying, preheating at 120-300°C, injecting HCHO, and measuring resistance changes.

5：Data Analysis Methods:

Gas response is defined as Ra/Rg, where Ra is resistance in air and Rg in HCHO. Data from XRD, SEM, TEM, Raman, XPS, BET, and gas sensing tests are analyzed to characterize structure, morphology, composition, and sensing performance.