The photoproduction of hot electron/hole pairs forms the basis for activating TiO2-based photovoltaic cells as well as for environmental remediation for removal of toxic materials[1]. We have separated the activation of adsorbed molecular oxygen by holes (causing O2 desorption) from activation by electrons (causing photooxidation reactions). I will show how controlled band bending can be used to determine which charge carrier is responsible for a carrier-mediated surface process [2].         In addition, we have observed that defect-bound Ti(3d) electrons in the near surface region act to compete with the Knotek-Feibleman (KF) mechanism [3] for O+ formation during electron stimulated desorption (ESD). One OH group, produced by water adsorption, causes the suppression of ESD-induced ionization to O+ of about 5 surface bridge-bonded O atoms on TiO2(110). Here Ti(3d) defect-bound electrons compete with the interatomic Auger process of the KF mechanism leading to O+ production. It is postulated that this is caused by defect-electron spreading across the surface away from an OH species attached to a surface oxygen vacancy defect site [4].

Watching hot carriers in TiO<sub>2</sub> excited by UV radiation

247th National Meeting (2014)

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Watching hot carriers in TiO2 excited by UV radiation

Watching hot carriers in TiO₂ excited by UV radiation