Effect of Water Adsorption on the Interfacial Structure and Band Edge Alignment of Anatase TiO2(001)/Water by First-Principles Molecular Dynamics

Abstract

The generation of hydrogen by photoelectrochemical (PEC) water splitting is a promising pathway to produce renewable and scalable carbon-free energy. To improve the performance of PEC cells, it is essential to understand the structural and electronic properties of the photoelectrode/electrolyte heterogeneous interfaces. By performing first-principles molecular dynamics (FPMD) simulations, we revealed the dynamic structure, such as water dissociation and adsorption and hydrogen bond network, and the band edge alignment of the TiO2/water interfaces. Mixed molecular and dissociative water adsorption is adopted at the (001)/water interface with a water dissociation percentage of ∼25% stabilized at ambient conditions, in contrast to the unstable water dissociation at the (101)/water interface. The different interfacial structures for the two surfaces lead to their distinct proton transfer processes. The calculated band edge alignment across the interfaces shows good agreement with the experimental data and exp...