Low-Cost, Efficient, and Durable H2 Production by Photoelectrochemical Water Splitting with CuGa3Se5 Photocathodes

Christopher Muzzillo, Walter Klein, Kai Zhu, Alexander DeAngelis, Kimberly Horsley, Nicolas Gaillard, Zhen Li

Research output: Contribution to journalArticlepeer-review

33 Scopus Citations


Photoelectrochemical (PEC) water splitting is an elegant method of converting sunlight and water into H2 fuel. To be commercially advantageous, PEC devices must become cheaper, more efficient, and much more durable. This work examines low-cost polycrystalline chalcopyrite films, which are successful as photovoltaic absorbers, for application as PEC absorbers. In particular, Cu-Ga-Se films with wide band gaps can be employed as top cell photocathodes in tandem devices as a realistic route to high efficiencies. In this report, we demonstrate that decreasing Cu/Ga composition from 0.66 to 0.31 in Cu-Ga-Se films increased the band gap from 1.67 to 1.86 eV and decreased saturated photocurrent density from 18 to 8 mA/cm2 as measured by chopped-light current-voltage (CLIV) measurements in a 0.5 M sulfuric acid electrolyte. Buffer and catalyst surface treatments were not applied to the Cu-Ga-Se films, and they exhibited promising stability, evidenced by unchanged CLIV after 9 months of storage in air. Finally, films with Cu/Ga = 0.36 (approximately stoichiometric CuGa3Se5) and 1.86 eV band gaps had exceptional durability and continuously split water for 17 days (∼12 mA/cm2 at -1 V vs RHE). This is equivalent to ∼17 200 C/cm2, which is a world record for any polycrystalline PEC absorber. These results indicate that CuGa3Se5 films are prime candidates for cheaply achieving efficient and durable PEC water splitting.

Original languageAmerican English
Pages (from-to)19573-19579
Number of pages7
JournalACS Applied Materials and Interfaces
Issue number23
StatePublished - 2018

Bibliographical note

Publisher Copyright:
© 2018 American Chemical Society.

NREL Publication Number

  • NREL/JA-5K00-71606


  • chalcopyrite
  • hydrogen
  • photoelectrochemical
  • polycrystalline
  • water splitting


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