Van der waals edge epitaxial growth of SnSe2-SnS2 lateral heterostructure for enhanced photocatalytic performance

Two-dimensional transition metal dichalcogenides (TMDs) have garnered significant attention in optoelectronic due to their unique structural and electronic properties. Among them, SnSe 2 and SnS 2 offer advantages of abundant reserves, low price and facile processing. In this work, we successfully synthesized SnSe 2 -SnS 2 nanosheets with an interesting lateral heterostructure via van der Waals edge epitaxial growth using a hydrothermal method. Density Functional Theory (DFT) calculations of surface energy and interfacial adhesion work revealed that the stronger covalent bonding between their (100) planes is the key thermodynamic factor governing the preferred lateral growth mode, despite their comparable lattice mismatch. The synergistic effect between the lateral heterojunction and the S-scheme interface with Se/S vacancies establishes a robust built-in electric field, which drastically promotes the excitation, separation, and migration of photogenerated charges, thereby significantly enhancing the photocatalytic activity. Evaluation of the photocatalytic performance demonstrated that the heterostructure degrades methyl orange (MO) at a rate 7.9 and 3.8 times faster than pure SnSe 2 and SnS 2 , respectively, and maintains over 70% of its initial activity after six consecutive cycles. This work provides mechanistic insights into the lateral growth mode of 2D materials and, through the synergistic design of band alignment and interface engineering, offers a novel paradigm for developing highly efficient and stable photocatalysts.