Published November 25, 2020 | Version v1
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Improved photoelectrochemical water splitting of CaNbO2N photoanodes by Co-Pi photodeposition and surface passivation

  • 1. Paul Scherrer Institut (PSI), 5232 Villigen, Switzerland
  • 2. Center for Nanointegration Duisburg-Essen, Technical Chemistry I, University of Duisburg-Essen, 47057 Duisburg, Germany
  • 3. Department of Chemistry, University of Zurich, 8057 Zurich, Switzerland

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Description

Photoelectrochemical solar water splitting is a promising approach to convert solar energy into sustainable hydrogen fuel using semiconductor electrodes. Due to their visible light absorption properties, oxynitrides have shown to be attractive photocatalysts for this application. In this study, the influence of the preparation method of CaNbO2N particles on their morphological and optical properties, and thereby their photoelectrochemical performance, is investigated. The best performing CaNbO2N photoanode is produced by ammonolysis of Nb enriched calcium niobium oxide. The enhanced photoactivity arises from an enlarged surface area and superior visible light absorption properties. The photoactivity of this photoanode was further enhanced by photodeposition of Co-Pi co-catalyst and by atomic layer deposition of an Al2O3 overlayer. A photocurrent density of 70 mA at 1.23 V vs RHE was achieved. The observed enhancement of the photoelectrochemical performance after Co-Pi/Al2O3 deposition is the combined effect of the improved kinetics of oxygen evolution due to the Co-Pi co-catalyst and the reduced surface recombination of the photogenerated carriers at the Al2O3 surface layer.

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References

Journal reference
F. Haydous, W. Si, V. A. Guzenko, F. Waag, E. Pomjakushina, M. El Kazzi, L. Sévery, A. Wokaun, D.Pergolesi, T. Lippert, J. Phys. Chem. C, 123, 1059−1068 (2019), doi: 10.1021/acs.jpcc.8b09629

Preprint
F. Haydous, W. Si, V. A. Guzenko, F. Waag, E. Pomjakushina, M. El Kazzi, L. Sévery, A. Wokaun, D.Pergolesi, T. Lippert, arXiv:1902.07470 [physics.app-ph]