Nonlayered Tin Thiohypodiphosphate Nanosheets: Controllable Growth and Solar-Light-Driven Water Splitting

As a promising candidate in various fields, including energy conversion and electronics, layered van der Waals metal phosphorus trichalcogenides (MPX₃) have been widely explored. In addition to the layered structures, MPX₃ comprising post-transition metals (i.e., Sn and Pb) are known to form a unique 3D framework with nonlayered structure. However, the nonlayered two-dimensional (2D) crystals of this family have remained unexplored until now. Herein, we successfully synthesized 2D nonlayered tin thiohypodiphosphate (Sn₂P₂S₆) nanosheets, having an indirect bandgap of 2.25 eV and a thickness down to ∼10 nm. The as-obtained nanosheets demonstrate promising photocatalytic water splitting activity to generate H₂ in pure water under simulated solar light (AM 1.5G). Moreover, the ultrathin Sn₂P₂S₆ catalyst shows auspicious performance and stability with a continuous operation of 40 h. This work is not only an expansion of the MPX₃ family, but it is also a major milestone in the search for new materials for future energy conversion.