1：Experimental Design and Method Selection:

The study employed a hydrothermal method to synthesize GQD/Bi2WO6 composites.

2：Sample Selection and Data Sources:

Bi2WO6 was synthesized via hydrothermal method, and GQD were synthesized by a recorded method. Different volumes of GQD were added to Bi2WO6 to form composites.

3：List of Experimental Equipment and Materials:

Equipment included a Shimadzu XRD-6000 diffractometer, JEOL JSM-7001F SEM, JEOL-JEM-2010 TEM, ESCALab MKII XPS spectrometer, IS50 FT-IR, UV-vis spectrophotometer, and TriStar 3020 BET analyzer. Materials included Bi(NO3)2·5H2O, Na2WO4·2H2O, and GQD.

4：Experimental Procedures and Operational Workflow:

The photocatalytic N2 fixation test was performed under a 300 W Xe lamp, with the ammonia synthesis rate determined by Nessler’s reagent method. Electrochemical analyses were conducted using a CHI660B electrochemical workstation.

5：Data Analysis Methods:

The optical absorption property was tested by UV-Vis diffuse reflectance spectrums, and the specific surface area was calculated with the BET method.