Construction of 2D/2D SiC/BiOBr heterostructures with strengthened photocatalysis for pollutants removal and NH3 production

Emerging research reveals that two-dimensional silicon carbide (2D SiC) exhibits superior properties over bulk SiC materials. Herein, the successful synthesis of 2D SiC by a novel top-down approach is primarily achieved and subsequently used for modification of BiOBr nanosheets to construct 2D/2D SiC/BiOBr heterojunctions via hydrothermal process. The 2D SiC nanosheets with lamellar structure are tightly stacked with flake BiOBr in the as-prepared heterojunctions. The highest visible light-driven degradation efficiencies of Rhodamine B, levofloxacin, tetracycline, and cephalexin under the catalysis of 2D/2D SiC/BiOBr are 1.65, 1.62, 1.16, and 2.44 times than that of BiOBr, respectively. Furthermore, the maximum NH₃ generation rate attains 0.0798 mmol⋅gcat^-1⋅h^-1 for 2D/2D SiC/BiOBr, achieving 3.92-folds enhancement relative to pristine BiOBr (0.0203 mmol⋅g_cat^-1⋅h^-1). The enhanced photocatalysis originates from facilitated charge carrier separation and improved photoresponsivity, which are verified by photoluminescence spectra, transient photocurrent, Tafel curves, turn-over frequency, electrochemical impedance spectroscopy, Mott-Schottky plots, and UV-vis absorption spectra, etc. Moreover, the dominant active species responsible for RhB degradation is determined to be superoxide radicals (^.O₂^–) radicals. Additionally, the 2D SiC/BiOBr heterojunctions exhibit remarkable stability during the photocatalytic degradation process. This study reveals that 2D SiC modification is an effective route to boost the photocatalytic activity of BiOBr, which may further expand its potential as a co-catalyst for other semiconductor-based photocatalytic systems.