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

Todd Deutsch, James Young, Alejandro Martinez-Garcia, Barry Russell, William Paxton, Srikanth Ravipati, Sonia Calero-Barney, Madhu Menon, Ernst Richter, Mahendra Sunkara

Research output: Contribution to journalArticlepeer-review

16 Scopus Citations


Here, 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.

Original languageAmerican English
Article number1703247
Number of pages9
JournalAdvanced Energy Materials
Issue number16
StatePublished - 2018

Bibliographical note

Publisher Copyright:
© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

NREL Publication Number

  • NREL/JA-5900-70812


  • bandgap tuning
  • DFT calculations
  • HVPE
  • III–V alloy
  • water splitting


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