1：Experimental Design and Method Selection:

The study employed a simple impregnation method followed by high-temperature annealing to dope tungsten into BiVO4 single crystal particles, aiming to enhance their electronic properties without altering their structure and morphology. Theoretical models included density functional theory (DFT) calculations to understand electronic changes.

2：Sample Selection and Data Sources:

BiVO4 single crystal particles were synthesized hydrothermally using NH4VO3 and Bi(NO3)3·5H2O precursors. W-BiVO4 was prepared by impregnating BiVO4 with WCl6 in ethanol, followed by annealing.

3：List of Experimental Equipment and Materials:

Equipment included a Teflon-lined stainless steel autoclave, centrifuge, XRD diffractometer (Rigaku RINT-Ultima III), UV-Vis spectrometer (JASCO V-670), SEM (Hitachi SU-8000), electrochemical analyzer (Princeton Applied Research 2273), potentiostat (Hokuto Denko HSV-100), solar simulator (SAN-EI Electric XES-301 S), Xe lamp (Asahi Spectra MAX-302), spectroradiometer (EKO Instruments LS-100), gas chromatograph (Shimadzu GC-8A), and computational tools (VASP, BOLTZTRAP). Materials included NH4VO3, Bi(NO3)3·5H2O, nitric acid, ammonia solution, ethanol, WCl6, Co(NO3)2, KPi electrolyte, AgNO3, La2O3, and various chemicals from Wako.

4：Experimental Procedures and Operational Workflow:

BiVO4 synthesis involved hydrothermal treatment at 200°C for 12 h. W doping was done by impregnation with WCl6 in ethanol, stirring, drying, and annealing at 500°C for 2 h. Electrodes were prepared using a particle transfer method with Ti and Au layers. PEC measurements used a three-electrode setup with Ag/AgCl reference and Pt counter electrodes under AM 1.5 G light. Photocatalytic O2 evolution was measured in a closed system with a Xe lamp and gas chromatography.

5：5 G light. Photocatalytic O2 evolution was measured in a closed system with a Xe lamp and gas chromatography. Data Analysis Methods:

5. Data Analysis Methods: Data were analyzed using XRD for structure, UV-Vis for absorption, SEM and EDS for morphology and elemental mapping, XPS for oxidation states, Mott-Schottky plots for carrier density, I-V curves for conductivity, IPCE calculations, and DFT for electronic properties.