Surface Hydroxylation during Water Splitting Promotes the Photoactivity of BiVO₄(010) Surface by Suppressing Polaron-Mediated Charge Recombination

Abstract

Polaron-based electron transport restricts the photoelectrochemical (PEC) water splitting efficiency of BiVO4. However, the location and dynamics of polarons are significantly dependent on the surface hydroxylation. By performing ab initio nonadiabatic molecular dynamics simulations, we demonstrated that hydroxylation of BiVO4(010) surface greatly alleviates the detrimental effect of oxygen-vacancy-induced electron polaron (EP). Surface hydroxylation stabilizes the EP at the surface to facilitate water splitting, makes the polaron a shallow localized state, and reduces the intensity of high-frequency V–O bond stretching vibrations. By decreasing the nonadiabatic coupling and decoherence time, the charge carrier lifetimes are extended by 1–3 orders of magnitude depending on the hydroxylation coverage. Our study not only reveals that the surface hydroxylation mitigated detrimental impacts of polarons in metal oxides but also provided valuable insights into the benign effect of intermediate species on the photocatalytic reactivity.

Nonadiabatic Molecular Dynamics with Non-Condon Effect of Charge Carrier Dynamics

“…The NA-MD simulations are conducted using the Python Extension for Ab Initio Dynamics (PYXAID) code utilizing the decoherence-induced surface hopping (DISH) algorithm . Its single k-point version has been successfully used to study photoexcitation dynamics in various materials. − More elaborate theoretical methodology and computational details can be found in the Supporting Information.…”

“…However, there is still a significant gap in the development of comparable theoretical tools, especially for first-principles approaches. A case in point is the time-dependent density functional theory (TD-DFT) anchored nonadiabatic molecular dynamics (NA-MD), − which evolve the electron population on the MD trajectories computed with a single k-point in the momentum space subjected to electron transfers driven by electron–phonon couplings to maintain momentum conservation. The limitation inhibits exploration into nonradiative multiphonon transition assisted charge dynamics, such as intra- and intervalley scattering and indirect electron–hole recombination.…”

Nuclear Quantum Effects Accelerate Charge Separation and Recombination in g-C3N4/TiO2 Heterojunctions

“…The 3–4 ps out of the 5 ps trajectories were selected from both AIMD and RPMD trajectories as initial configurations for NA-MD simulations by using PYXAID software. , In particular, electron transfer was simulated by using the fewest switches surface hopping (FSSH) method, while the nonradiative electron–hole recombination was simulated by using the decoherence-induced surface hopping (DISH) method, because the decoherence time is significantly shorter than the quantum transition time. The approaches have been applied to study the photoexcitation dynamics in various condensed-phase materials. − The methods for calculating decoherence and spectral density are detailed in the Supporting Information.…”