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Title: Low-Cost, Efficient, and Durable H 2 Production by Photoelectrochemical Water Splitting with CuGa 3Se 5 Photocathodes

Photoelectrochemical (PEC) water splitting is an elegant method of converting sunlight and water into H 2 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/cm 2 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 CuGa 3Se 5) and 1.86 eV band gaps had exceptional durability and continuously split water for 17 days (~12 mA/cm 2 at -1 V vs RHE). This is equivalent to ~17 200 C/cm 2, which is a world recordmore » for any polycrystalline PEC absorber. These results indicate that CuGa 3Se 5 films are prime candidates for cheaply achieving efficient and durable PEC water splitting.« less
Authors:
ORCiD logo [1] ;  [1] ;  [1] ;  [2] ;  [2] ; ORCiD logo [1] ;  [2]
  1. National Renewable Energy Lab. (NREL), Golden, CO (United States)
  2. Univ. of Hawaii, Honolulu, HI (United States)
Publication Date:
Report Number(s):
NREL/JA-5K00-71606
Journal ID: ISSN 1944-8244
Grant/Contract Number:
AC36-08GO28308
Type:
Accepted Manuscript
Journal Name:
ACS Applied Materials and Interfaces
Additional Journal Information:
Journal Volume: 10; Journal Issue: 23; Journal ID: ISSN 1944-8244
Publisher:
American Chemical Society (ACS)
Research Org:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; chalcopyrite; hydrogen; photoelectrochemical; polycrystalline; water splitting
OSTI Identifier:
1456867