Motif-dependent carrier relaxation dynamics in g - heterostructures: A nonadiabatic molecular dynamics study

Abstract

Van der Waals heterostructures provide an effective platform for regulating interfacial charge transfer and carrier dynamics in photocatalytic systems. Here, we combine first-principles calculations and nonadiabatic molecular dynamics (NAMD) simulations to investigate triazine- and heptazine-based g-C3N4/MoSi2N4 heterostructures. Although both systems exhibit type-II–like band alignment in static electronic-structure calculations, their excited-state carrier dynamics display fundamentally different behaviors. The triazine-based heterostructure shows faster carrier relaxation and more efficient interfacial carrier transfer, whereas the heptazine-based heterostructure exhibits prolonged carrier lifetime associated with hybridized band-edge states and modified carrier-phonon interactions. Further analysis reveals that the distinct relaxation dynamics cannot be fully explained solely by static band alignment or averaged nonadiabatic coupling strengths, highlighting the critical role of electronic-state hybridization and structural motifs in regulating carrier dynamics in two-dimensional photocatalytic heterostructures.