Controlled synthesis of Bi2S3/g-C3N4 nanosheets for efficient degradation of rhodamine B and reduction of Cr (VI) under visible light

s In this study, a flower-shaped Bi 2 S 3 /g-C 3 N 4 heterostructure was synthesized via a hydrothermal method and utilized as a visible-light-driven photocatalyst for the removal of hexavalent chromium (Cr 6+ ) and Rhodamine B (RhB). Employing an interface electronic engineering strategy with heterostructure nanosheets, the thickness of the nanosheets was adjusted by varying the molecular weight of the structure guiding agent, polyethylene glycol (Mn = 400, 2000 or 4000). Under visible light irradiation for 18 and 60 minutes, the removal efficiencies of Cr 6+ and RhB reached 95.0 % and 99.9 %, respectively, with corresponding rate constants being 8.64-fold and 9.67-fold higher than pure Bi 2 S 3 . The enhanced photocatalytic efficiency may be attributed to the intermediate adsorption states and increased active sites enhancing light absorption and charge separation. Furthermore, species capture studies revealed that electrons (e - ) and superoxide radicals (·O 2 - ) played crucial roles in the reduction of chromium (VI), while holes (h + ) were the primary active species involved in RhB degradation. Density-functional theory (DFT) calculation demonstrated charge redistribution and electron accumulation can be more obviously observed at Bi 2 S 3 /g-C 3 N 4 than Bi 2 S 3 , which proved that g-C 3 N 4 doping effectively improved the electrons transfer efficiency over the Bi 2 S 3 /g-C 3 N 4 surface, thereby enhancing the photocatalytic activity.