High Efficiency Si Photocathode Protected by Multifunctional GaN Nanostructures

Elisabetta Arca, Glenn Teeter, Srinivas Vanka, Shaobo Cheng, Kai Sun, Gianluigi Botton, Zetian Mi

Research output: Contribution to journalArticlepeer-review

84 Scopus Citations


Photoelectrochemical water splitting is a clean and environmentally friendly method for solar hydrogen generation. Its practical application, however, has been limited by the poor stability of semiconductor photoelectrodes. In this work, we demonstrate the use of GaN nanostructures as a multifunctional protection layer for an otherwise unstable, low-performance photocathode. The direct integration of GaN nanostructures on n+-p Si wafer not only protects Si surface from corrosion but also significantly reduces the charge carrier transfer resistance at the semiconductor/liquid junction, leading to long-term stability (>100 h) at a large current density (>35 mA/cm2) under 1 sun illumination. The measured applied bias photon-to-current efficiency of 10.5% is among the highest values ever reported for a Si photocathode. Given that both Si and GaN are already widely produced in industry, our studies offer a viable path for achieving high-efficiency and highly stable semiconductor photoelectrodes for solar water splitting with proven manufacturability and scalability.

Original languageAmerican English
Pages (from-to)6530-6537
Number of pages8
JournalNano Letters
Issue number10
StatePublished - 10 Oct 2018

Bibliographical note

Publisher Copyright:
© 2018 American Chemical Society.

NREL Publication Number

  • NREL/JA-5K00-72535


  • Gallium nitride
  • hydrogen
  • nanowire
  • photocathode
  • silicon
  • solar fuel
  • water splitting


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