  Understanding the dynamic nature of the semiconductor-water interface is
crucial for developing efficient photoelectrochemical water splitting
catalysts, as it governs reactivity through charge and mass transport. In this
study, we employ ab initio molecular dynamics simulations to investigate the
structural and dynamical properties of water at the $\beta$-TaON (100) surface.
We observed that a well-defined interface is established through the
spontaneous dissociation of water and the reorganization of surface chemical
bonds. This leads to the formation of a partially hydroxylated surface,
accompanied by a strong network of hydrogen bonds at the TaON-water interface.
Consequently, various proton transport routes, including the proton transfer
through "low-barrier hydrogen bond" path, become active across the interface,
dramatically increasing the overall rate of the proton hopping at the
interface. Based on our findings, we propose that the observed high
photocatalytic activity of TaON-based semiconductors could be attributed to the
spontaneous water dissociation and the resulting high proton transfer rate at
the interface.
