Premium
Covalent Surface Modification of Gallium Arsenide Photocathodes for Water Splitting in Highly Acidic Electrolyte
Author(s) -
Garner Logan E.,
Steirer K. Xerxes,
Young James L.,
Anderson Nicholas C.,
Miller Elisa M.,
Tinkham Jonathan S.,
Deutsch Todd G.,
Sellinger Alan,
Turner John A.,
Neale Nathan R.
Publication year - 2017
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201601408
Subject(s) - photoelectrolysis , photocurrent , water splitting , photoelectrochemistry , chemistry , electrolyte , covalent bond , desorption , photoelectrochemical cell , reversible hydrogen electrode , photochemistry , inorganic chemistry , electrode , materials science , adsorption , electrochemistry , working electrode , electrolysis , optoelectronics , catalysis , organic chemistry , photocatalysis
Efficient water splitting using light as the only energy input requires stable semiconductor electrodes with favorable energetics for the water‐oxidation and proton‐reduction reactions. Strategies to tune electrode potentials using molecular dipoles adsorbed to the semiconductor surface have been pursued for decades but are often based on weak interactions and quickly react to desorb the molecule under conditions relevant to sustained photoelectrolysis. Here, we show that covalent attachment of fluorinated, aromatic molecules to p‐GaAs(1 0 0) surfaces can be employed to tune the photocurrent onset potentials of p‐GaAs(1 0 0) photocathodes and reduce the external energy required for water splitting. Results indicate that initial photocurrent onset potentials can be shifted by nearly 150 mV in pH −0.5 electrolyte under 1 Sun (1000 W m −2 ) illumination resulting from the covalently bound surface dipole. Though X‐ray photoelectron spectroscopy analysis reveals that the covalent molecular dipole attachment is not robust under extended 50 h photoelectrolysis, the modified surface delays arsenic oxide formation that results in a p‐GaAs(1 0 0) photoelectrode operating at a sustained photocurrent density of −20.5 mA cm −2 within −0.5 V of the reversible hydrogen electrode.