Tunable Interfacial Electronic and Photoexcited Carrier Dynamics of an S-Scheme MoSi2N4/SnS2 Heterojunction

Exploring and designing an efficient S-scheme heterojunction photocatalyst for water splitting are crucial. Herein, we report the interfacial electronics, photoexcited carrier dynamics, and photocatalytic performance for water splitting of the MoSi2N4/SnS2 van der Waals heterojunction under the modulation of an electric field and biaxial strain. Our results show that the MoSi2N4/SnS2 heterojunction has a direct band gap of 0.41 eV and obeys the S-scheme charge transfer mechanism. Further calculations of the photoexcited carrier dynamics demonstrate that the interfacial carrier recombination time is 7.22 ps, which is shorter than the electron (hole) transfer time of 39.5 ps (566 ps). Moreover, under the effect of a positive electric field and tensile strain, the S-scheme MoSi2N4/SnS2 heterojunction exhibits excellent visible-light absorption, satisfactory band-edge potentials, tunable interfacial charge transfer, and spontaneous hydrogen evolution reaction activity. The calculated STH efficiency indicates that a tensile strain of 2% is the most effective means of improving the photocatalytic performance of the S-scheme MoSi2N4/SnS2 heterojunction.