Exploring defect induced fluorescence in borophene dots

• Oxygen-related defects introduced during the synthesis of borophene dots are critical in enabling photoluminescence. • The borophene dots exhibit near UV-blue fluorescence with a maximum emission at 416 nm under excitation at 290 nm. • Defect-mediated radiative transitions are the primary source of fluorescence in borophene dots. • Defects, such as boron-hydride and boron-oxygen functional groups, significantly influence light absorption and emission. • A dual decay in photoluminescence lifetime underscores contributions from both intrinsic band structures and defect states. Borophene dots are emerging as promising zero-dimensional nanomaterials due to their unique structural, electronic, and photophysical properties, particularly their defect-induced fluorescence. This study introduces a novel, scalable synthesis for obtaining fluorescent borophene dots by thermal degradation of sodium borohydride in air. The borophene processing involves controlled heating and intermediate cooling cycles. This route enables incorporating oxygen-related defects as active sites for fluorescence under ambient conditions. Comprehensive characterization techniques, including TEM, AFM, XPS, FTIR, and photoluminescence spectroscopy, reveal that the interplay between boron-hydride and oxygen functional groups modulates the photophysical properties of borophene dots. The findings demonstrate that oxygen-related defects enhance light absorption and emission, with photoluminescence arising from defect-mediated radiative transitions. Defect engineering plays a primary role in tailoring the optical properties of borophene dots, which can be used in optoelectronics, sensing, and bioimaging.