Interfacial charge separation and strain-tunable electronic properties of type-II MoS2/g-C3N4 heterojunctions: A first-principles and nonadiabatic dynamics study

Abstract

Efficient separation and transport of photogenerated carriers are crucial for improving 2D photocatalysts. Here, a MoS2/g-C3N4 vdW heterojunction is investigated using first-principles calculations and NAMD. The optimized heterojunction is structurally stable and exhibits a type-II band alignment, with the CBM mainly localized on MoS2 and the VBM on g-C3N4. Differential charge-density analysis reveals interfacial charge redistribution and dipole formation, while biaxial strain effectively tunes the band gap and band-edge character. Optical absorption spectra, and HER/OER free-energy analysis further support its potential for visible-light–driven photocatalytic water splitting. NAMD simulations show that photogenerated electrons and holes undergo interfacial transfer on the picosecond timescale, with electron and hole transfer times of 7.22 and 2.06 ps. The e-h recombination lifetime reaches 466 ps, much longer than those of isolated MoS2 and g-C3N4, indicating suppressed nonradiative recombination. These results clarify the microscopic charge-separation mechanism of MoS2/g-C3N4 and provide guidance for designing efficient 2D photocatalytic heterojunctions.