Dual regulation of photocatalytic processes by intrinsic polarization and heterointerface engineering in...

Intrinsic polarization in Janus 2D materials provides an effective strategy for regulating charge separation in photocatalysis. However, static band alignment alone cannot fully describe photocatalytic performance, because carrier migration, transfer, and recombination after photoexcitation are governed by excited-state dynamics. Here, first-principles calculations combined with time-domain NAMD simulations were used to investigate MoSi₂N₄/MoSi₂N₃P Janus heterostructures. The results show that asymmetric P substitution induces out-of-plane polarization and polarization-dependent band alignment, enabling a transition between type-I and type-II heterojunctions through stacking regulation. Compared with AC¹, the AC² configuration exhibits type-II band alignment, more effective spatial separation of photogenerated electrons and holes, and a slightly longer e-h recombination lifetime. Nonadiabatic dynamics further reveal that polarization reversal modifies carrier-transfer pathways and weakens nonradiative recombination by reducing e-h wavefunction overlap. These findings demonstrate that intrinsic polarization and heterointerface engineering jointly regulate both static electronic structures and excited-state carrier dynamics, providing microscopic guidance for the design of Janus-based photocatalysts.