Extracting kinetic information on the hydrogen evolution on Pt by combining time-resolved microcalorimetry and finite-element modelling.

ChemRxiv

Abstract

For fast and reversible electrocatalytic reactions, like the hydrogen evolution on Pt in acidic media and in the presence of molecular H 2 , it is very challenging to obtain reliable kinetic information from the charge-potential relationship alone. To overcome this issue, we measure the time-resolved heat flux during hydrogen evolution on polycrystalline Pt as complementary information to chronopotentiometric measurements. The interpretation of the data is based on a comparison with a finite element simulation comprising a microkinetic model coupled to mass transport. Using this approach, we estimate the exchange current density to be around 10 – 15 mA cm -2 , for both, the Tafel or the Heyrovský reaction being the rate limiting step. We also find that the coverage of the active hydrogen intermediate is low around the equilibrium potential, even in hydrogen saturated solution.

Authors 4

1. Marco Schönig Aachen

   Karlsruhe Institute of Technology · Leiden University

   Affiliation as printed

   Institute of Physical Chemistry, Karlsruhe Institute of Technology, Kaiserstraße 12, Karlsruhe, Germany, 76131

   Leiden Institute of Chemistry, Leiden University, PO Box 9501, Leiden, Netherlands, 2300 RA

2. Katherine J. Levey Aachen

   Leiden University

   Affiliation as printed

   Leiden Institute of Chemistry, Leiden University, PO Box 9501, Leiden, Netherlands, 2300 RA

3. Marc T. M. Koper Aachen

   Leiden University

   Affiliation as printed

   Leiden Institute of Chemistry, Leiden University, PO Box 9501, Leiden, Netherlands, 2300 RA

4. Rolf Schuster

   Karlsruhe Institute of Technology

   Affiliation as printed

   Institute of Physical Chemistry, Karlsruhe Institute of Technology, Kaiserstraße 12, Karlsruhe, Germany, 76131