Solar thermal decoupled water electrolysis process III: The anodic electrochemical reaction in a rotating disc electrode cell

Rachel Silcox, Laura K. Engerer, Shahin Nudehi, Paul Smith, Jon Schoer, Peter T. Krenzke, Robert Palumbo, Luke J. Venstrom

Research output: Contribution to journalArticlepeer-review

Abstract

The electrochemical oxidation of Co2+ is studied at 45 °C using a rotating disc electrode to elucidate the impacts of fluid motion and solid Co3+ product formation on the anode reaction rate. The electrolyte is 40% KOH saturated with Co2+ and the anode is nickel. Inducing laminar flow with rotation at speeds up to 2500 RPM is shown to increase the current density from <1 mA cm-2 to 2–5 mA cm-2 at potentials greater than −0.21 Volts vs. Ag/AgCl. At higher current densities anticipated for commercial application, electrode passivation is a relevant concern. However, bulk electrolysis and cyclic voltammetry—with the latter interpreted using a reaction model to account for the fluid motion—demonstrate that the solid Co3+ deposit is not passivating, but electrochemically active. Deposits up to ≈1 mm thick increase the current, with a sixfold increase demonstrated at 2000 RPM.

Original languageEnglish (US)
Article number115885
JournalChemical Engineering Science
Volume227
DOIs
StatePublished - Dec 14 2020

Bibliographical note

Funding Information:
We are grateful to the National Science Foundation for supporting this work with award number 1334896. Use of the Center for Nanoscale Materials, an Office of Science user facility, was supported by the U.S. Department of Energy , Office of Science , Office of Basic Energy Sciences , under Contract No. DE-AC02-06CH11357 . We thank Rachel Koritala for SEM training.

Funding Information:
We are grateful to the National Science Foundation for supporting this work with award number 1334896. Use of the Center for Nanoscale Materials, an Office of Science user facility, was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. We thank Rachel Koritala for SEM training.

Publisher Copyright:
© 2020 Elsevier Ltd

Keywords

  • Cobalt oxide
  • Concentrated solar energy
  • Electrolysis
  • Hydrogen
  • Rotating disc electrode
  • Voltammetry

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