Wet Electrons at the H ₂ O/TiO ₂ (110) Surface

Abstract

At interfaces of metal oxide and water, partially hydrated or "wet-electron" states represent the lowest energy pathway for electron transfer. We studied the photoinduced electron transfer at the H2O/TiO2(110) interface by means of time-resolved two-photon photoemission spectroscopy and electronic structure theory. At approximately 1-monolayer coverage of water on partially hydroxylated TiO2 surfaces, we found an unoccupied electronic state 2.4 electron volts above the Fermi level. Density functional theory shows this to be a wet-electron state analogous to that reported in water clusters and which is distinct from hydrated electrons observed on water-covered metal surfaces. The decay of electrons from the wet-electron state to the conduction band of TiO2 occurs in </=15 femtoseconds.

Surface photochemistry probed by two-photon photoemission spectroscopy

“…[20][21][22][23][24][25][26] Recently, the application of the 2PPE technique has also been extended to the study of excited electronic structure and dynamics of adsorbates on metal oxide surfaces, [27][28][29] which serve as models for practical catalytic or photocatalytic systems. The application of 2PPE in the study of metal oxide systems provides us with some hope that this method could be used to study photocatalytic processes at surfaces.…”

Spectroscopy and control of near-surface defects in conductive thin film ZnO

“…34,35 Beyond these slow electrons, a Since 2PPE simultaneously probes both the occupied and unoccupied levels, the origin of a spectroscopic feature can be identified by measuring the final state energy as a function of photon energy. To this end, the excitation energy was varied over a range of 600 meV.…”

Experimental and theoretical studies of hydroxyl-induced magnetism in TiO nanoclusters

“…[7][8][9][10] As a large number of metal oxides have comparable oxygen vacancy and hydroxyl concentrations, it is suggested that they share the same hydroxylation mechanism. 11 The (110) rutile TiO 2 surface has been used as a model system to investigate the hydroxylation process.…”