The transformation of solar energy into chemical energy stored in the form of hydrogen, through photoelectrochemical water splitting is a promising method with the important advantage of being environment friendly and free from carbon dioxide emission. Several metal oxide semiconductors are able to split water into hydrogen and oxygen but the efficiencies are still low. Several strategies were proposed to improve the photoelectrochemical properties like doping or nanostucturing, but the origin of the improvement is not well understood yet. In the laboratory, we study the photo-electrochemical activity of thin epitaxial oxide films in order to understand the influence of different parameters on the photoanode efficiency.
(a) Current density versus applied voltage vs Ag/AgCl for the undoped sample and 17 % Ti doped Fe2O3 one in dark, under illumination and with chopped light. (b) photocurrent density as a function of the Ti doping level at 0.4 V (circle) and 0.6 V (square) vs Ag/AgCl.(from Applied Phys. Lett. 101 (2012) 133908)
Faits marquants :
Hematite-based epitaxial thin films as photoanodes for solar water splitting (Maxime Rioult), 2012-2015, supervisors: H. Magnan, A. Barbier
Photoelectrolysis of water by internal polarization (Sukanya Datta), 2015; supervisors: A. Barbier, H. Magnan
Hématite monocristalline nanostructurée pour la photo-électrolyse de l’eau (Maxime Rioult), 2012, supervisor: H. Magnan
Manipulating the ferroelectric polarization state of BaTiO3 thin films, S. Datta, M. Rioult, D. Stanescu, H. Magnan, A. Barbier, Thin Solid Films 607, 7 - 13 (2016)
Oxygen Vacancies Engineering of Iron Oxides Films for Solar Water Splitting, M. Rioult, D. Stanescu, E. Fonda, A. Barbier, H. Magnan, J. Phys. Chem. C, 120 (14), pp 7482–7490 (2016)
Tailoring the photocurrent in BaTiO3/Nb:SrTiO3 photoanodes by controlled ferroelectric polarization, M. Rioult, S. Datta, D. Stanescu, S. Stanescu, R. Belkhou, F. Maccherozzi, H. Magnan, A. Barbier, Appl. Phys. Lett. 107, 103901 (2015)
Local electronic structure and photoelectrochemical activity of partial chemically etched Ti doped hematite, M. Rioult, R. Belkhou, H. Magnan, D. Stanescu, S. Stanescu, F. Maccherozzi, C. L. Rountree, A. Barbier, Surf. Sci. 641, 310 (2015)
Single crystalline hematite films for solar water splitting: Ti-doping and thickness effect M. Rioult, H. Magnan, D. Stanescu, A. Barbier, J. Phys. Chem C. 118, 3007 (2014)
Enhanced photo-anode properties of epitaxial Ti doped a-Fe2O3 (0001) thin films, H. Magnan, D. Stanescu, M. Rioult, E. Fonda, A. Barbier, Appl. Phys. Lett. 101, 133908(2012).
This work is supported by a public grant overseen by the French National Research Agency (ANR) as part of the “Investissements d’Avenir” program (Labex NanoSaclay, reference: ANR-10-LABX-0035)