Ultrafast Charge Transfer and Delayed Recombination in a Type-II Ni₃TeO₆/MoSi₂N₄ Heterostructure: A Time-Domain Ab Initio Study

Despite the potential of two-dimensional (2D) materials as photocatalysts, efficient carrier recombination limits their practical applicability. Leveraging first-principles calculations and nonadiabatic molecular dynamics, we propose a type-II van der Waals magnetic Ni₃TeO₆/MoSi₂N₄ heterostructure as a favorable candidate for photocatalytic water splitting. It exhibits a high Young’s modulus of 621 N/m, indicating significantly enhanced resistance to deformation compared to its constituent monolayers. The band edges align with water redox levels while maintaining a band gap of 2.22 eV, thereby promoting overall water splitting. Excited-state carrier dynamics analyses are performed to elucidate the charge-transfer route. Our findings reveal rapid electron and hole relaxation processes (161 and 126 fs, respectively) relative to electron-hole recombination. The short decoherence time of 2.61 fs and weak nonadiabatic coupling suggest slow interlayer recombination, permitting charge carriers to participate effectively in redox reactions. Free-energy calculations disclose that the hydrogen evolution reaction (HER) proceeds efficiently in heterostructures with oxygen vacancies (OVs). Further, OVs improve the photocatalytic efficiency of the heterostructure, reaching 17.12%. This research offers profound insights into the photocatalytic water-splitting mechanisms in the Ni₃TeO₆/MoSi₂N₄ heterostructure and provides a route to boost the performance, contributing to advancements in sustainable energy applications.