Molecular Insights into the Water Dissociation and Proton Dynamics at the $\beta$-TaON (100)/Water Interface

TL;DR

This study uses ab initio molecular dynamics to reveal how water dissociates and facilitates proton transfer at the $eta$-TaON (100)/water interface, explaining its high photocatalytic activity.

Contribution

It provides detailed atomic-level insights into water dissociation and proton dynamics at the $eta$-TaON surface, linking these processes to photocatalytic efficiency.

Findings

Water spontaneously dissociates at the interface.

A network of hydrogen bonds facilitates proton transfer.

Proton hopping rates are significantly increased at the interface.

Abstract

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.