1：Experimental Design and Method Selection:

The study uses a one-step photochemical synthesis method involving the photoreduction of graphene oxide (GO) and transition metal salts using α-aminoalkyl radicals generated from the organic photocatalyst I-907 under UVA radiation. This method is chosen for its environmental friendliness and scalability.

2：Sample Selection and Data Sources:

GO is prepared from graphite using a modified Hummers method. Solutions include GO dispersed in acetonitrile with I-907 and optionally cobalt chloride for composite formation.

3：List of Experimental Equipment and Materials:

Equipment includes a UVP CL-1000L UV crosslinker for UVA irradiation, an Agilent Cary 60 Spectrophotometer for UV-vis spectroscopy, a Phillips CM200 instrument for TEM/HRTEM/SAED/EDS, a Thermo ESCALAB250i XPS spectrometer, a Renishaw inVia 2 Raman spectrometer, and a CHI 760 Electrochemical Workstation. Materials include graphite (Alfa Aesar), anhydrous acetonitrile (Sigma-Aldrich), I-907 (Sigma-Aldrich), cobalt(II) chloride hexahydrate (Ajax Fine Chem), ethanol (Chem-Supply), Nafion perfluorinated resin (Sigma-Aldrich), alumina powder, KOH (Chem-Supply), and carbon fiber paper (Fuel Cell Store).

4：Experimental Procedures and Operational Workflow:

For synthesis, solutions are ultrasonicated, deaerated with argon, and irradiated with UVA for 3 hours. Products are purified by centrifugation and redispersion. Characterization involves UV-vis, XPS, Raman, TEM, HRTEM, SAED, and EDS. Electrochemical tests use a three-electrode system with linear sweep voltammetry, chronopotentiometry, and rotating ring-disk electrode measurements in 1 M KOH.

5：Data Analysis Methods:

Data analysis includes calculating C/O ratios from XPS, ID/IG ratios from Raman spectra, onset potentials and Tafel slopes from LSV curves, and Faradaic efficiency from RRDE measurements using specified formulas.