Intrinsic bifunctional photocatalytic water splitting and high carrier mobility in novel Janus SnXNH (X = S/Se/Te) monolayers: a first-principles prediction.

The pursuit of innovative materials for next-generation technologies has stimulated significant interest in two-dimensional Janus systems. Herein, based on density functional theory we propose and investigate physical properties of SnXNH (X = S/Se/Te) monolayers. Their crystal structures and dynamical stabilities are first evaluated. The computational results indicate that while SnSNH and SnSeNH are dynamically stable, SnTeNH is determined to be unstable. Consequently, only these two stable monolayers are subsequently examined in detail for their thermal, energetic, and mechanical stabilities, as well as their electronic, transport, and photocatalytic characteristics. The results confirm the thermal stability at room temperature of SnSNH and SnSeNH systems, along with strong energetic and mechanical robustness, indicating their feasibility for experimental synthesis. Electronic structure calculations reveal that SnSNH and SnSeNH are direct-bandgap semiconductors with bandgap energies ranging from 0.29 to 2.13 eV. In particular, SnSNH exhibits a suitable bandgap, making it a promising candidate for future exploration in photovoltaic applications. Carrier transport properties indicate that electron mobilities in both SnSNH and SnSeNH monolayers are significantly higher than those of holes due to their smaller effective masses. Moreover, the SnSNH monolayer demonstrates pronounced anisotropy in carrier mobility with respect to both transport direction and carrier type. From the large surface potential differences, the band edge positions of SnSNH and SnSeNH satisfy the requirements for water redox potential. Overall, these findings provide valuable insights that may inspire further exploration of novel two-dimensional Janus structures as efficient electronic and photocatalytic materials for technological applications.