Chemical Modification of Polaronic States in Anatase TiO2(101)

Two polymorphs of TiO2, anatase and rutile, are employed in photocatalytic applications. It is broadly accepted that the more catalytically active subsequently finds wider commercial use. In this work, we focus on Ti3+ polaronic states TiO2(101), which lie at ∼1.0 eV binding energy known to increase catalytic performance. Using UV-photoemission two-photon photoemission spectroscopies, demonstrate capability tune excited state resonance polarons by controlling chemical environment. Anatase TiO2(101) contains subsurface undergo sub-band-gap photoexcitation ∼2.0 above Fermi level. Formic acid adsorption dramatically influences states, increasing ∼0.3 eV. Moreover, oscillator strength changes significantly, resonating with ∼3.0 We show behavior likely due surface migration oxygen vacancies.