Abstract:In this study，orange peel carbon dots （OPCDs） were synthesized via a hydrothermal method using orange peel，a processing byproduct，as the carbon source. Ultraviolet-visible spectra revealed a characteristic absorption peak at 278 nm，indicating the presence of a graphitic carbon core structure. Fluorescence spectrum analysis showed that the optimal excitation wavelength was 360 nm，with a corresponding emission peak at444 nm. X-ray diffraction analysis and transmission electron microscope results indicate that the orange peel carbon dots are amorphous spherical particles with a particle size of 5-20 nm. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy confirmed the presence of abundant functional groups on the surface，including Cpagenumber_ebook=80,pagenumber_book=72C，C—O，and Cpagenumber_ebook=80,pagenumber_book=72O. The Zeta potential was determined to be -25.94 mV，indicating good solution stability. Antimicrobial activity tests showed that the minimal inhibit concentration （MIC） of OPCDs against Staphylococcus aureus was 1.25 mg/mL，and the minimum bactericidal concentration （MBC）was 5 mg/mL. The diameter of the inhibition zone increased significantly with increasing concentration，reaching （24.30±0.44） mm at 8 MIC. OPCDs effectively inhibited bacterial growth and hindered biofilm formation.Antioxidant activity tests revealed that at a concentration of 1 mg/mL，OPCDs exhibited scavenging rates of 94.42% against DPPH radicals and 97.95% against ABTS+radicals. In conclusion，OPCDs demonstrate promising potential for applications in antimicrobial and antioxidant materials.