Electrocatalytic hydrogen evolution under densely buffered neutral pH conditions

Type
Article

Authors
Shinagawa, Tatsuya
Takanabe, Kazuhiro

KAUST Department
Catalysis for Energy Conversion (CatEC)
Chemical Science Program
KAUST Catalysis Center (KCC)
Physical Science and Engineering (PSE) Division

Online Publication Date
2015-08-24

Print Publication Date
2015-09-03

Date
2015-08-24

Abstract
Under buffered neutral pH conditions, solute concentrations drastically influence the hydrogen evolution reaction (HER). The iR-free HER performance as a function of solute concentration was found to exhibit a volcano-shaped trend in sodium phosphate solution at pH 5, with the maximum occurring at 2 M. A detailed microkinetic model that includes calculated activity coefficients, solution resistance, and mass-transport parameters accurately describes the measured values, clarifying that the overall HER performance is predominantly governed by mass-transport of slow phosphate ions (weak acid). In the HER at the optimum concentration of approximately 2 M sodium phosphate at pH 5, our theoretical model predicts that the concentration overpotential accounts for more than half of the required overpotential. The substantial concentration overpotential would originate from the electrolyte property, suggesting that the proper electrolyte engineering will result in an improved apparent HER performances. The significance of concentration overpotential shown in the study is critical in the advancement of electrocatalysis, biocatalysis, and photocatalysis.

Citation
Electrocatalytic hydrogen evolution under densely buffered neutral pH conditions 2015:150818150957008 The Journal of Physical Chemistry C

Publisher
American Chemical Society (ACS)

Journal
The Journal of Physical Chemistry C

DOI
10.1021/acs.jpcc.5b05295

Additional Links
http://pubs.acs.org/doi/abs/10.1021/acs.jpcc.5b05295

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