Actions for Photo-induced water oxidation at the aqueous GaN (101 ̄0) interface [electronic resource] : Deprotonation kinetics of the first proton-coupled electron-transfer step

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Photo-induced water oxidation at the aqueous GaN (101 ̄0) interface [electronic resource] : Deprotonation kinetics of the first proton-coupled electron-transfer step

Published
Washington, D.C. : United States. Dept. of Energy. Office of Basic Energy Sciences, 2015.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy
Physical Description
pages 2,317-2,323 : digital, PDF file
Additional Creators
Brookhaven National Laboratory, United States. Department of Energy. Office of Basic Energy Sciences, and United States. Department of Energy. Office of Scientific and Technical Information
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Summary
Photoeclectrochemical water splitting plays a key role in a promising path to the carbon-neutral generation of solar fuels. Wurzite GaN and its alloys (e.g., GaN/ZnO and InGaN) are demonstrated photocatalysts for water oxidation, and they can drive the overall water splitting reaction when coupled with co-catalysts for proton reduction. In the present work, we investigate the water oxidation mechanism on the prototypical GaN (101 ̄0) surface using a combined ab initio molecular dynamics and molecular cluster model approach taking into account the role of water dissociation and hydrogen bonding within the first solvation shell of the hydroxylated surface. The investigation of free-energy changes for the four proton-coupled electron-transfer (PCET) steps of the water oxidation mechanism shows that the first PCET step for the conversion of –Ga-OH to –Ga-O ̇− requires the highest energy input. We further examine the sequential PCETs, with the proton transfer (PT) following the electron transfer (ET), and find that photo-generated holes localize on surface –NH sites is thermodynamically more favorable than –OH sites. However, proton transfer from –OH sites with subsequent localization of holes on oxygen atoms is kinetically favored owing to hydrogen bonding interactions at the GaN (101 ̄0)–water interface. We find that the deprotonation of surface –OH sites is the limiting factor for the generation of reactive oxyl radical ion intermediates and consequently for water oxidation.
Report Numbers
E 1.99:bnl--107983-2015-ja
bnl--107983-2015-ja
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Note
Published through SciTech Connect.
03/12/2015.
"bnl--107983-2015-ja"
"KC0301020"
ACS Catalysis 5 4 ISSN 2155-5435 AM
Ertem, Mehmed; Kharche, Neerav; Batista, Victor; Hybertsen, Mark; Tully, John; Muckerman, James.
Funding Information
SC00112704
CO045
View MARC record | catkey: 24046554