Authors: López-Caballero, Patricia; Ramallo-Lopez, Jose M.; Giovanetti, Lisandro J.; Buceta, David; Miret-Artés, Salvador; Lopez-Quintela, M. Arturo; Requejo, Felix G.; de Lara-Castells, Maria Pilar
Journal: JOURNAL OF MATERIALS CHEMISTRY A
Publication date: 2020/04/14
Abstract: Using a combination of first-principles modelling, X-ray absorption spectroscopy, and diffuse reflectance spectroscopy measurements, we explore the properties of Ag-5-modified TiO2 surfaces. A general electron polarization phenomenon associated with surface polarons on TiO2 has been revealed theoretically and confirmed experimentally. First, the Ag-5 cluster donates an electron to TiO2, leading to the formation of polaronic Ti3+ 3d(1) states on the rutile TiO2(110) surface. The analysis of polarization effects in the nearby electronic structure accompanying the polaron formation is confirmed with X-ray absorption spectroscopy measurements at the Ti K-edge of TiO2 nanoparticles. Next, the UV-Vis optical absorption spectrum of the polaronic state is also computationally modelled and an enlargement of the polaron wavefunction is predicted. Moreover, we find an overall improvement of the UV-Vis optical response of the material through diffuse reflectance spectroscopy measurements. Finally, we predict that charge-transfer processes at the Ag-5-TiO2 interface triggered by solar photons might allow for a photoinduced activation of CO2 by sunlight.