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In Operando Deconvolution of Photovoltaic and Electrocatalytic Performance in ALD TiO2 Protected Water Splitting Photocathodes

preprint
revised on 02.10.2017 and posted on 02.10.2017 by David Tilley, Wei Cui, Wenzhe Niu, René Wick, Thomas Moehl

Many present-day investigations of water splitting photoelectrodes are based on buried p–n junctions, which usually offer an improved photovoltage and therefore a higher solar-to-hydrogen efficiency in tandem photoelectrochemical cells. In this work, we demonstrate that the dual working electrode (DWE) technique enables the measurement of the surface potential of water splitting buried-junction photocathodes under operation, enabling the deconvolution of the photovoltaic and electrocatalytic performance in operando. Consequently, we can access properties of the buried p–n junction independent of the surface kinetics, and gain information related to the charge transfer through the electrode/electrolyte interface independent of the photovoltaic properties. Moreover, the DWE technique provides a clearer understanding of the photocathode degradation mechanism during stability tests. Two p–n junction-based photocathodes are investigated in this work: a pn+-Si/TiO2 photocathode as model system, and the application of the developed method to the emerging material system Cu2O/Ga2O3/TiO2.

History

Topic

  • Energy Storage

Email Address of Submitting Author

david.tilley@chem.uzh.ch

Institution

University of Zurich

Country

Switzerland

ORCID For Submitting Author

0000-0002-7542-1147

Declaration of Conflict of Interest

The authors declare no conflict of interest.

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