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Title: Unassisted Water Splitting Using a GaSb xP (1- x ) Photoanode

Here in this work, unbiased water splitting with 2% solar-to-hydrogen efficiency under AM 1.5 G illumination using new materials based on GaSb 0.03P 0.97 alloy is reported. Freestanding GaSb xP 1-x is grown using halide vapor phase epitaxy. The native conductivity type of the alloy is modified by silicon doping, resulting in an open-circuit potential (OCP) of 750 mV, photocurrents of 7 mA cm -2 at 10 sun illumination, and corrosion resistance in an aqueous acidic environment. Alloying GaP with Sb at 3 at% improves the absorption of high-energy photons above 2.68 eV compared to pure GaP material. Electrochemical Impedance Spectroscopy and illuminated OCP measurements show that the conduction band of GaSb xP 1-x is at -0.55 V versus RHE irrespective of the Sb concentration, while photocurrent spectroscopy indicates that only radiation with photon energies greater than 2.68 eV generate mobile and extractable charges, thus suggesting that the higher-laying conduction bands in the Γ 1 valley of the alloys are responsible for exciton generation.
Authors:
 [1] ;  [1] ;  [2] ;  [2] ;  [1] ;  [3] ;  [4] ;  [5] ;  [5] ;  [6]
  1. Univ. of Louisville, KY (United States). Department of Chemical Engineering
  2. Univ. of Louisville, KY (United States). Conn Center for Renewable Energy Research
  3. Univ. of Louisville, KY (United States). Center for Computational Sciences
  4. Daimler AG, RD/EKB, Ulm (Germany)
  5. National Renewable Energy Lab. (NREL), Golden, CO (United States)
  6. Univ. of Louisville, KY (United States). Department of Chemical Engineering and Conn Center for Renewable Energy Research
Publication Date:
Report Number(s):
NREL/JA-5900-70812
Journal ID: ISSN 1614-6832
Grant/Contract Number:
AC36-08GO28308
Type:
Accepted Manuscript
Journal Name:
Advanced Energy Materials
Additional Journal Information:
Journal Name: Advanced Energy Materials; Journal ID: ISSN 1614-6832
Publisher:
Wiley
Research Org:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Fuel Cell Technologies Office (EE-3F)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; bandgap tuning; DFT calculations; HVPE; III-V alloy; water splitting
OSTI Identifier:
1426640
Alternate Identifier(s):
OSTI ID: 1422018