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Unassisted Water Splitting Using a GaSb x P (1− x ) Photoanode
Author(s) -
MartinezGarcia Alejandro,
Russell Harry B.,
Paxton William,
Ravipati Srikanth,
CaleroBarney Sonia,
Me Madhu,
Richter Ernst,
Young James,
Deutsch Todd,
Sunkara Mahendra K.
Publication year - 2018
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201703247
Subject(s) - materials science , photocurrent , analytical chemistry (journal) , dielectric spectroscopy , band gap , alloy , spectroscopy , water splitting , conductivity , absorption (acoustics) , optoelectronics , electrochemistry , metallurgy , chemistry , biochemistry , physics , electrode , chromatography , quantum mechanics , photocatalysis , composite material , catalysis
Abstract Here, unbiased water splitting with 2% solar‐to‐hydrogen efficiency under AM 1.5 G illumination using new materials based on GaSb 0.03 P 0.97 alloy is reported. Freestanding GaSb x P 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 x P 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.