Charge carrier recombination processes, intragap defect states, and photoluminescence mechanisms in stoichiometric and reduced TiO<sub>2</sub> brookite nanorods: an interpretation scheme through <i>in situ</i> photoluminescence excitation spectroscopy in controlled environment
Romina Rega, Ambra Fioravanti, Seyedsina Hejazi, Mahdi Shahrezaei, Štěpán Kment, P. Maddalena, Alberto Naldoni, S. Lettieri
Abstract
photoluminescence excitation spectroscopy in controlled environment. Through an investigation procedure employing both supragap and subgap excitation during successive exposure to oxidizing and reducing gaseous agents, we firstly obtained an interpretation scheme describing the main photoluminescence and charge recombination pathways in stoichiometric and reduced brookite, which includes information about the spatial and energetic position of the intragap states involved in photoluminescence mechanisms, and secondly identified a specific photoluminescence enhancement process occurring in only reduced brookite nanorods, which indicates the injection of a conduction band electron during ethanol photo-oxidation. The latter finding may shed light on the empirical evidence about the exceptional reactivity of reduced brookite nanorods toward the photo-oxidation of alcohols and the concomitant efficiency of photocatalytic hydrogen generation.