Highly efficient and dual-functional photochemical elimination of Cr2O72− and reactive dyes via fabrication of a novel S-scheme binary heterojunction In2S3/In-MOF

Abstract

Photocatalytic elimination of highly toxic Cr₂O₇²⁻ and stubborn reactive dyes requires photocatalysts to exhibit both robust oxidation and reduction capabilities. However, most single MOFs must utilize ultraviolet light and are incapable of concurrently providing sufficiently negative LUCO and positive HUCO potentials. In the current contribution, a water-stable In-MOF featured by typical n-type semiconductor was assembled and subsequently integrated with the in-situ growth In₂S₃ to construct a novel In₂S₃/In-MOF binary heterojunction. Notably, the intrinsic LUCO (−0.43 eV, vs. NHE) and HOCO (2.77 eV, vs. NHE) energy levels of deployed In-MOF exhibit a suitable band dislocation with In₂S₃'s CB (−0.85 eV, vs. NHE) and VB (1.43 eV, vs. NHE) potentials. And this integration facilitates the establishment of an S-Scheme carrier transfer mechanism, effectively inhibiting carriers recombination and ensuring the efficient utilization of the robust redox abilities offered by In₂S₃'s CB and In-MOF's HOCO. Under the driven of a low-energy xenon lamp, In₂S₃/In-MOF's optical-electrical properties involving photosensitiveness, photocurrent intensity and interface resistance have been notably improved. M55, with a feed mass ratio of In-MOF to In₂S₃ at 5 : 5, achieved a 99.9 % reduction efficiency for Cr(VI) within 80 min, degradation efficiencies of 77 % and 82 % for reactive dyes RB21 and RR2 within 12 h, respectively. Its reaction kinetics have increased by 8.79, 17.82 and 14.55 times compared to the pristine In-MOF, and by 1.66, 4.60 and 17.57 times relative to pure In₂S₃. This contribution offers a viable avenue for designing novel MOFs-based photocatalysts, which possess robust reducing and oxidizing capabilities, to address some intractable water pollution issues.