Integration of double halogen atoms in atomically thin bismuth bromide: Mutative electronic structure steering charge carrier migration boosted broad-spectrum photocatalysis

Abstract

Herein, an ionic liquid-assisted solvothermal method was applied to synthesize the atomically thin BiOBr0.5I0.5 solid solution (BOBI-AT) nanosheets with 2–3 layer thickness. Characterization and DFT calculation results clearly revealed that fabricating solid solution system optimized the total solar light utilization efficiency, especially in the long-wavelength-region, as well as the density of states by integrating two different halogen atoms in intrinsic BiOBr. BOBI-AT showed the highest broad-spectrum photodegradation efficiency towards colorless antibiotic tetracycline among bulk BiOBr0.5I0.5 solid solution, atomically thin BiOBr and BiOI materials under visible light illumination (λ > 400 or 580 nm, respectively). The evidently enhanced photocatalytic degradation performance of BOBI-AT system was attributed to the interior effect of the double halogen atoms Br and I induced the mutative density of states in the intrinsic BiOBr material, which significantly accelerating the charge separation and transfer efficiency in the BOBI-AT. Meanwhile, the atomically thin structure greatly shortened the photogenerated charge transfer distance. Solid solution with atomically thin structure bidirectional regulation strategy on charge separation and transfer was first proposed in this work, which provides a new insight for bismuth oxyhalide photocatalyst optimization and their application in energy conversion and environment treatment.