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Proceedings Paper

Controlling photo-activity of solution-processed hematite electrodes for solar water splitting
Author(s): Kevin Sivula; Jeremie Brillet; Michael Grätzel
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Paper Abstract

Hematite is a promising material for solar energy conversion via photo-electrochemical water splitting. However, the precise control of substitutional doping and nanometer feature size is important for high photon harvesting efficiency. Doped and nanostructured hematite electrodes can be prepared by a simple solution-based colloidal approach however, a high temperature (800°C) annealing is required to activate the dopant atoms. This high temperature annealing step also increases the particle size above the dimension necessary for high photon harvesting efficiencies. Here we investigate a strategy to control the two kinetic processes occurring during sintering (particle size increase and dopant diffusion/activation) by incorporating Ti dopant directly into the colloid solution and reducing the annealing time. We find that this strategy leads to porous, high-surface area hematite electrodes giving a solar photocurrent density of 1.1 mA cm-2 at 1.23 V vs. the reversible hydrogen electrode (RHE) under standard testing conditions where only 0.56 mA cm-2 was observed at 1.23 V vs. RHE with our previous work. In addition, scanning electron micrographs examining the morphology of the electrodes suggests that our kinetic strategy is indeed effective and that further optimization may result in higher photocurrents.

Paper Details

Date Published: 24 August 2010
PDF: 6 pages
Proc. SPIE 7770, Solar Hydrogen and Nanotechnology V, 77700G (24 August 2010); doi: 10.1117/12.860199
Show Author Affiliations
Kevin Sivula, Ecole Polytechnique Fédérale de Lausanne (Switzerland)
Jeremie Brillet, Ecole Polytechnique Fédérale de Lausanne (Switzerland)
Michael Grätzel, Ecole Polytechnique Fédérale de Lausanne (Switzerland)

Published in SPIE Proceedings Vol. 7770:
Solar Hydrogen and Nanotechnology V
Hicham Idriss; Heli Wang, Editor(s)

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