Interfacial C=C bond engineering promotes S-scheme-like charge-transfer dynamics in van der Waals heterojunctions
Phys. Rev. B 114, 165306 – Published 29 September, 2026
DOI: https://doi.org/10.1103/2ppr-gy45
Abstract
S-scheme heterojunctions offer a route to separate photogenerated carriers while retaining strong redox capability, but how interfacial chemical modification controls the underlying carrier dynamics remains insufficiently understood. Here, we systematically investigate the carrier dynamics of pristine hexagonal boron nitride and C=C-doped van der Waals heterojunctions using first-principles calculations combined with nonadiabatic molecular dynamics (NAMD) simulations. Both pristine and doped heterojunctions exhibit a staggered type-II band alignment in their static electronic structures. C=C bonding, however, reduces the work function of hBNC, increases its Fermi-level offset relative to , and enhances the interfacial dipole and built-in electric field. The NAMD results reveal distinct charge-transfer behaviors in the two systems: Pristine is dominated by hole transfer, whereas C=C-doped exhibits much faster interfacial electron-hole recombination than interlayer electron or hole transfer. This change in the kinetic hierarchy suppresses the conventional type-II relaxation pathway and supports S-scheme-like carrier-transfer dynamics in the doped heterojunction. Moreover, free-energy calculations of the key hydrogen evolution reaction and oxygen evolution reaction steps further validate the photocatalytic advantage predicted by the preceding electronic-structure and carrier-dynamics analyses. Our findings provide a mechanistic understanding of how interfacial C=C bond engineering promotes kinetically favored S-scheme-like carrier dynamics while simultaneously improving the thermodynamic feasibility of photocatalytic water splitting.
