posted on 2024-01-22, 23:11authored byYun-Bo Li, Rutong Si, Bo Wen, Xiao-Lin Wei, Nicola Seriani, Wen-Jin Yin, Ralph Gebauer
Understanding
the behavior of a polaron in contact with water is
of significant importance for many photocatalytic applications. We
investigated the influence of water on the localization and transport
properties of polarons at the rutile (110) surface by constrained
density functional theory. An excess electron at a dry surface favors
the formation of a small polaron at the subsurface Ti site, with a
preferred transport direction along the [001] axis. As the surface
is covered by water, the preferred spatial localization of the polarons
is moved from the subsurface to the surface. When the water coverage
exceeds half a monolayer, the preferred direction of polaron hopping
is changed to the [110] direction toward the surface. This characteristic
behavior is related to the Ti3d-orbital occupations and
crystal field splitting induced by different distorted structures
under water coverage. Our work describes the reduced sites that might
eventually play a role in photocatalysis for rutile (110) surfaces
in a water environment.