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Local electronic structure and photoelectrochemical activity of partial chemically etched Ti-doped hematite

DOI: 10.1016/j.susc.2015.01.002 DOI Help

Authors: Maxime Rioult (CEA-Saclay) , Rachid Belkhou (Synchrotron Soleil) , Hélène Magnan (CEA-Saclay) , Stefan Stanescu (Synchrotron Soleil) , Dana Stanescu (CEA-Saclay) , Francesco Maccherozzi (Diamond Light Source) , Cindy Rountree (CEA-Saclay) , Antoine Barbier (CEA-Saclay)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Surface Science , VOL 641 , PAGES 310–313

State: Published (Approved)
Published: January 2015
Diamond Proposal Number(s): 9024

Abstract: photoelectrochemical water splitting is promising as a clean hydrogen production solution. Ti-doped hematite (Ti:α-Fe2O3) is a potential key photoanode material, which despite its optimal band gap, excellent chemical stability, abundance, non-toxicity and low cost, still has to be improved. Here we give evidence of a drastic improvement of the water splitting performances of Ti-doped hematite photoanodes upon a HCl wet-etching. In addition to the topography investigation by atomic force microscopy, a detailed determination of the local electronic structure has been carried out in order to understand the phenomenon and to provide new insights in the understanding of solar water splitting. Using synchrotron radiation based spectromicroscopy (X-PEEM), we investigated the X-ray absorption spectral features at the L3 Fe edge of the as grown surface and of the wet-etched surface on the very same sample thanks to patterning. We show that HCl wet etching leads to substantial surface modifications of the oxide layer including increased roughness and chemical reduction (presence of Fe2 +) without changing the band gap. We demonstrate that these changes are profitable and correlated to the drastic changes of the photocatalytic activity.

Journal Keywords: Fe2O3; Ti Doping; Peem; Photoanode; Surface Etching; Photoelectrolysis

Subject Areas: Chemistry

Instruments: I06-Nanoscience