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

Journal Article · · Advanced Energy Materials
 [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
+ Show Author Affiliations

Here in this work, unbiased water splitting with 2% solar-to-hydrogen efficiency under AM 1.5 G illumination using new materials based on GaSb0.03P0.97 alloy is reported. Freestanding GaSbxP1-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 GaSbxP1-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.

Research Organization:
National Renewable Energy Laboratory (NREL), Golden, CO (United States)
Sponsoring Organization:
USDOE; USDOE Office of Energy Efficiency and Renewable Energy (EERE), Fuel Cell Technologies Office (EE-3F)
Grant/Contract Number:
AC36-08GO28308
OSTI ID:
1426640
Report Number(s):
NREL/JA--5900-70812
Journal Information:
Advanced Energy Materials, Journal Name: Advanced Energy Materials Journal Issue: 16 Vol. 8; ISSN 1614-6832
Publisher:
WileyCopyright Statement
Country of Publication:
United States
Language:
English

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Cited By (2)

A methodological review on material growth and synthesis of solar-driven water splitting photoelectrochemical cells journal January 2019
Photoelectrochemical water oxidation of GaP 1−x Sb x with a direct band gap of 1.65 eV for full spectrum solar energy harvesting journal January 2019

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