1：Experimental Design and Method Selection:

The study involved synthesizing nitrogen and boron co-doped graphene oxide (NB/GO) using an ultrasound-assisted method in aqueous ammonia and boric acid solutions, followed by annealing under nitrogen atmosphere. This method allows for tuning doping levels by controlling ultrasonication temperature and annealing conditions.

2：Sample Selection and Data Sources:

Graphene oxide powder (purity >

3：5 wt%) was used as the starting material, purchased from Sinocarbon Graphene Marketing Center. Other chemicals like boric acid and aqueous ammonia were obtained from Aladdin. List of Experimental Equipment and Materials:

Key equipment included a bath sonicator for ultrasonication, a furnace for annealing under N2 atmosphere, X-ray photoelectron spectroscopy (XPS) using a K-Alpha spectrometer (Thermo Fisher Scientific Inc.), scanning electron microscopy (SEM) with FEI Quanta 600 FEG, transmission electron microscopy (TEM) with JEOL 3000F, atomic force microscopy (AFM) with Agilent 5500 AFM/SPM system, Raman spectroscopy with Renishaw in Via Raman microscope, and electrochemical measurements using a CHI 760E electrochemical workstation and Pine AFMSRCE RDE control system. Materials included graphene oxide, boric acid, aqueous ammonia, ethanol, and KOH electrolyte.

4：Experimental Procedures and Operational Workflow:

Synthesis involved dispersing N/GO in boric acid solution, ultrasonicating at varying temperatures (5°C to 75°C) for 3 hours, and annealing at 700°C under N

5：Characterization included XPS, SEM, TEM, AFM, and Raman spectroscopy to analyze chemical composition, morphology, and structure. Electrochemical tests (CV and LSV) were performed in a three-electrode cell with Ag/AgCl reference, Pt counter, and glassy carbon working electrodes in O2-saturated 1 M KOH. Data Analysis Methods:

XPS data were calibrated to C 1s at 284.8 eV and deconvoluted to identify N and B species. Raman spectra were analyzed for D and G band ratios. Electrochemical data were analyzed using Koutecky-Levich equation to determine electron transfer numbers and Tafel slopes for ORR kinetics.