Nitrogen-doped graphyne/BiOBr nanocomposites: In-situ sonochemical synthesis and boosted photocatalytic performance

In this study, a facile in-situ sonochemical synthesis process is developed to construct nitrogen-doped graphyne/ BiOBr composites. Multiple techniques are implemented to characterize the structures, morphologies, electronic and optical properties, and photocatalytic activity of the as-prepared samples, including X-ray powder diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, Raman, and X-ray photoelectron spectroscopy, etc. The results indicate that the wrinkle-like layer structure of Ngraphyne enwinds around the sheet structure of BiOBr. Compared to pristine BiOBr, N-graphyne/BiOBr composites present superior visible-light response, higher specific surface area, and more significant separation of photoinduced charge carriers verified by Brunauer-Emmett-Teller, UV-vis absorption spectroscopy, instantaneous photocurrent, electrochemical impedance spectroscopy, and photoluminescence, thus presenting more pronounced visible-light photocatalytic properties on N2 fixation and decomposition of pollutants. The optimal ratio of N-graphyne in N-graphyne/BiOBr composites is screened out for the photocatalytic decomposition of rhodamine B, levofloxacin, methylene blue, and nitrogen fixation under visible light illumination. Furthermore, the main active species are demonstrated as hole and center dot O2- during photocatalytic degradation and the stable performance of is also observed for N-graphyne/BiOBr composites. The present research demonstrates that Ngraphyne embellishment is an effective strategy to enhance the photocatalytic efficiency of BiOBr, which can be broadened as an excellent co-catalyst for decoration of other semiconductors.