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O: Fachverband Oberflächenphysik

O 24: Focus Session: Structure and Chemistry of Metal-Oxide Surfaces I

O 24.6: Hauptvortrag

Dienstag, 13. März 2018, 12:15–12:45, MA 005

Photoelectrochemistry on hematite: a first-principles view — •Anders Hellman — Department of Physics and the Competence Centre for Catalysis, Chalmers University of Technology, Sweden

Fe2O3 is an abundant n-type semiconductor that has excellent stability in neutral and alkaline electrolytes, but so far the reported solar-to-hydrogen conversion efficiency is far from the theoretical limit [1]. Major factors hampering the performance of Fe2O3 are high recombination rate and poor oxygen evolution kinetics.

In a recent publication, we showed that joining different oxides provide the possibility of control the recombination rate [2]. The mechanism relies on the formation of dipole-like electric fields at the interface which, depending on the field direction, attract or repel minority carriers from the interface. Here we investigate the built-in electric field generated at the interfaces of using first-principles methods. The results show how electronic band alignment and defects doping at the interface determine the direction and strength of the built-in field. We also comment how these can affect the oxygen evolution kinetics via the overpotential. Our understanding of the oxide nanostructures can be employed for designing and improving the performance of water-splitting photoelectrodes.

[1]: D. K. Bora, A. Braun, E. C. Constable, Energy Environ. Sci., 2013, 6, 407. [2]: B. Iandolo,B. Wickman, E. Svensson, D. Paulsson, and A. Hellman, Nano Lett., 2016, 16, 2381.