Graphene nanoreactors : photoreduction of prussian blue in aqueous solution

Date
2017
Editor(s)
Advisor
Supervisor
Co-Advisor
Co-Supervisor
Instructor
Source Title
Journal of Physical Chemistry C
Print ISSN
1932-7447
Electronic ISSN
Publisher
American Chemical Society
Volume
121
Issue
40
Pages
22225 - 22233
Language
English
Journal Title
Journal ISSN
Volume Title
Series
Abstract

Prussian dyes are characterized by interesting photomagnetic properties due to the photoinduced electron transfer involved in the Fe oxidation and spin state changes. Ferromagnetic Prussian blue (PB) in contact with titanium dioxide (TiO2) can be reduced to paramagnetic Prussian white (PW) upon UV band gap excitation of TiO2. This process is promoted by the presence of a hole scavenger, such as water, fundamental to ensure the overall charge balance and the continuity of the process. In order to clarify the photoinduced reduction mechanism and the role of water, an innovative system of graphene nanobubbles (GNBs) filled with a PB aqueous solution was developed, enabling the application of electron spectroscopies to the liquid phase, up to now limited by the vacuum required to overcome the short electron inelastic mean free path in dense medium. In this work GNBs formed on the photocatalytic substrate are able to act as "nanoreactors", and they can control and take part in the reaction. The evolution of Fe L2,3 edge X-ray absorption spectra measured in total electron yield through the graphene membrane revealed the electron reduction from PB (FeIII-CN-FeII) to PW (FeII-CN-FeII) upon UV irradiation, shedding light on the photoinduced electron transfer mechanism in liquid phase. The results, confirmed also by Raman spectroscopy, unequivocally demonstrate that the reaction occurs preferentially in aqueous solution, where water acts as hole scavenger.

Course
Other identifiers
Book Title
Citation
Published Version (Please cite this version)