Abstract
Polarons are ubiquitous in many semiconductors and have been linked with conductivity and optical response of materials for photovoltaics and heterogeneous catalysis, yet how surface polarons influence adsorption remains unclear. Here, by modelling the surface of rutile titania using density functional theory, we reveal the effect of small surface polarons on water adsorption, dissociation, and hydrogen bonding. On the one hand the presence of such polarons significantly suppresses dissociation of water molecules that are bonded directly to polaronic sites. On the other hand, polarons facilitate water dissociation at certain non-polaronic sites. Furthermore, polarons strengthen hydrogen bonds, which in turn affects water dissociation in hydrogen bonded overlayer structures. This study reveals that polarons at the rutile surface have complex, multi-faceted, effects on water adsorption, dissociation and hydrogen bonding, highlighting the importance of polarons on water structure and dynamics on such surfaces. We expect that many of the physical properties of surface polarons identified here will apply more generally to surfaces and interfaces that can host small polarons, beyond titania.
Highlights
By modeling the surface of rutile titania using density functional theory, we reveal the effect of small surface polarons on water adsorption, dissociation, and hydrogen bonding
This study reveals that polarons at the rutile surface have complex, multifaceted, Janus-like effects on water adsorption, dissociation, and hydrogen bonding, highlighting the importance of polarons on water structure and dynamics on such surfaces
The fundamental physics of defects at clean surfaces and aqueous interfaces is of great importance to everyday processes such as wetting and nucleation, as well as the more application-oriented topics of photovoltaics and heterogeneous catalysis [1,2,3,4]
Summary
The fundamental physics of defects at clean surfaces and aqueous interfaces is of great importance to everyday processes such as wetting and nucleation, as well as the more application-oriented topics of photovoltaics and heterogeneous catalysis [1,2,3,4]. By modeling the surface of rutile titania using density functional theory, we reveal the effect of small surface polarons on water adsorption, dissociation, and hydrogen bonding. This study reveals that polarons at the rutile surface have complex, multifaceted, Janus-like effects on water adsorption, dissociation, and hydrogen bonding, highlighting the importance of polarons on water structure and dynamics on such surfaces.
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