Fanny Duquet defended her thesis on October 21, 2022
Photo-anode materials based on titanium and cobalt oxides for hydrogen production and water pollution control
front of the jury composed of:
– Ms Valérie KELLER, Director of Research at the CNRS, University of Strasbourg, rapporteur
– Mr Cédric BOISSIERE, Director of Research at CNRS, Sorbonne University, rapporteur
– Mrs Christina VILLENEUVE-FAURE, Associate Professor, University of Toulouse 3, examiner
– Mr Peter HESEMANN, Director of Research at CNRS, University of Montpellier, examiner
– Mrs Stéphanie ROUALDES, Associate Professor, University of Montpellier, thesis supervisor
– Mr. Matthieu RIVALLIN, Associate Professor, ENSCM, co-supervisor
– Mrs Florence ROUESSAC, Associate Professor, University of Montpellier, co-supervisor
Among the solutions for reducing atmospheric pollution and thus slowing down the current global warming, the use of “green” hydrogen as an energy carrier is attractive. Thanks to the use of a photoelectrochemical cell at the crossroads between water electrolysis and photocatalysis, hydrogen can be produced without greenhouse gas emissions. Moreover, the use of partially polluted water as a resource for this cell would allow the coupling between green hydrogen production and tertiary water treatment. In order to do this, work on the components of this cell, more precisely on the photo-anodes, is essential to make such a competitive system.
In this work, we developed sol-gel photo-anodic materials based on titanium and cobalt oxides, formed from various bio-sourced surfactants. Different physico-chemical and functional characterization techniques were used to highlight the effect of cobalt oxide (as a spinel phase in the bulk and as a Co(OH)2 hydroxide, rather than as an oxide, on the surface) on the structural, optical and photoelectrocatalytic properties of the materials, which are essentially composed of TiO2 in the anatase and rutile forms. In standard or polluted aqueous medium and under xenon irradiation, the mixed materials show better (photo)electrocatalytic properties and produce more hydrogen than the cobalt-free layers, and this cobalt-related improvement increases with increasing cobalt content. These results pave the way for the coupling of hydrogen production and water purification under sunlight, which has been shown to be possible with the materials developed in this thesis.