Construction of novel β-XY (X = Ge, Sn, Y = S)/g-C3N4 heterostructures: efficient visible light-driven water splitting catalysts

The logical design of inexpensive, non-polluting, and extremely effective photocatalysts is a crucial step toward achieving clean energy. The currently low solar-to-hydrogen (STH) conversion efficiency (η_STH) makes hydrogen production technologies less than optimal. Herein, novel β-XY (X = Ge, Sn, Y = S)/g-C₃N₄ heterostructures have been constructed. Among them, the β-SnS/g-C₃N₄ exhibits low carrier recombination, and its geometry, optoelectronic properties, as well as the thermodynamic feasibility of its reaction, have been thoroughly examined through DFT calculations. The results demonstrate that the β-SnS/g-C₃N₄ heterostructure is a type-II heterostructure, exhibiting an indirect band gap of 2.57 eV. Photocatalysis is more efficient because of the built-in electric field that extends from the g-C₃N₄ monolayer to the β-SnS monolayer, effectively separating electrons and holes. The continuously decreasing free energy validates the thermodynamic spontaneity of water splitting. Additionally, the heterostructure demonstrates robust absorption in both the visible and UV ranges. Notably, the η_STH of 15.54 % underscores the commercial viability of this material. These findings thus suggest that β-SnS/g-C₃N₄ heterostructure is a good candidate material for water splitting via photocatalysis.