Designing an innovative 2D/2D step scheme α-Fe₂O₃/BiOBr/MoS₂ ternary integrated heterojunction with unparalleled visible-light-induced remarkable photocatalytic H₂ evolution

This study presents a novel 2D/2D step scheme α-Fe₂O₃/BiOBr/MoS₂ ternary integrating heterojunction with unparalleled visible-light-induced enhanced photocatalytic hydrogen (H₂) production. We report the first successful integration of α-Fe₂O₃/BiOBr nanostructures with ultrathin MoS₂ layers via a hydrothermal process. This distinctive heterojunction, composed of Nanosheets (NSs) well characterized using XRD, TEM, STEM, SEM, XPS, EDX, PL and UV techniques. A unique covalent connection between α-Fe₂O₃ and BiOBr creates a BiOBr-OV system, which excels in charge carrier-mediated photocatalytic reactions. When we compared our ternary heterojunction containing more than one or two semiconductors with a single semiconductor, it showed perfect alignment of the bandgap, which is good for the disconnection of photogenerated carriers and also suppresses their recombination. So, these kinds of heterojunctions normally have higher hydrogen production rates. Until now binary composite α-Fe₂O₃/BiOBr shows the best activities as the photocatalyst, but when we compared it with our ternary composite α-Fe₂O₃/BiOBr/MoS₂ has an edge of minimum toxicity, tunable band gap, and maximum chemical stability up to ten cycles and also has best photocatalytic hydrogen evolution rate under the visible light irradiation. The optimized composite, consisting of 0.5 wt% α-Fe₂O₃/BiOBr loaded with 10 wt% MoS₂, exhibits remarkable stability over 180 h and achieves an exceptionally manifested quantum yield of 70.3% at 420 nm. A noteworthy breakthrough in solar hydrogen generation, this nanocomposite exhibits an astounding H₂ expansion rate of 57 mmol g⁻¹h⁻¹. The design principles established in this work have broad applicability for developing highly efficient materials for advanced energy storage and conversion systems.