Strain-induced electronic and photocatalytic properties of MoSi2N4/SMoSiN2 heterojunction

Based on the individual MoSi2N4 and SMoSiN 2 monolayers, we design an AA-stacked MoSi2N4/SMoSiN2 heterojunction (AA-HJ) with enhanced stability, confirmed by phonon dispersion analysis. The pristine AA-HJ exhibits a 2.13 eV indirect Type-I bandgap. Under -2% strain, it transforms into a Type-II heterojunction with a widened bandgap of 2.60 eV. An interfacial electrostatic potential difference drives charge transfer from MoSi2N4 to SMoSiN2 , establishing an intrinsic built-in electric field. This strain-induced band engineering facilitates efficient charge separation through built-in electric fields, enabling photocatalytic water splitting with oxygen evolution occurring in the SMoSiN2 layer and hydrogen generation in the MoSi2N4 layer. The AA-HJ(-2%) presents a good optical absorption in visible and ultraviolet regions, further confirming its potential as a sunlight-driven photocatalyst for water splitting applications.