Probing the Role of Surface Energetics of Electrons and their Accumulation in Photoreduction Processes on TiO2. Issue 25 (14th May 2014)

• Record Type: Journal Article
• Authors: Molinari, Alessandra; Maldotti, Andrea; Amadelli, Rossano
• Is Part Of: Chemistry. Volume 20:Issue 25(2014)
• Page Start: 7759
• Page End: 7765
• Publication Date: 2014-05-14
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201402039
• Languages: English
• ISSNs: 0947-6539

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>We address the role of the energetics of photogenerated electrons in the reduction of 4‐nitrobenzaldehyde on TiO₂. This model molecule bears two functional groups featuring different reducibilities. Electrochemistry shows that reduction to 4‐aminobenzyl alcohol occurs in entirely distinct potential ranges. Partial reduction of the NO₂ group, affording 4‐aminobenzaldehyde, takes place through surface states at potentials positive of the flatband potential (<italic>E</italic>_fb). Dark currents caused by reduction of the aldehyde group are observed only at potentials more negative than <italic>E</italic>_fb, and the process requires an electron accumulation regime. Photocatalysis with TiO₂ suspensions agrees with the electrochemical data. In particular, reduction of the nitro group is a relatively fast process (<italic>k</italic>=0.059 s⁻¹), whereas that of the aldehyde group is slower (<italic>k</italic>=0.001 s⁻¹) and requires electron photoaccumulation. Control of the photogenerated charge is a prospective means for achieving chemoselective reductions.</p> </abstract>