Effect of iron addition to the electrolyte on alkaline water electrolysis performance

Maximilian Demnitz; Yuran Martins Lamas; Rodrigo Lira Garcia Barros; Anouk de Leeuw den Bouter; John van der Schaaf; Matheus Theodorus de Groot

doi:10.1016/j.isci.2023.108695

Effect of iron addition to the electrolyte on alkaline water electrolysis performance

iScience. 2023 Dec 10;27(1):108695. doi: 10.1016/j.isci.2023.108695. eCollection 2024 Jan 19.

Authors

Maximilian Demnitz^{1

2}, Yuran Martins Lamas^{1

2}, Rodrigo Lira Garcia Barros^{1

2}, Anouk de Leeuw den Bouter^{1

2}, John van der Schaaf^{1

2}, Matheus Theodorus de Groot^{1

2}

Affiliations

¹ Department of Chemical Engineering and Chemistry, Sustainable Process Engineering Group, Eindhoven University of Technology, P.O. Box 513, Eindhoven 5600 MB, the Netherlands.
² Eindhoven Institute for Renewable Energy Systems, Eindhoven University of Technology, PO Box 513, Eindhoven 5600 MB, the Netherlands.

Abstract

Improvement of alkaline water electrolysis is a key enabler for quickly scaling up green hydrogen production. Fe is omnipresent within most industrial alkaline water electrolyzers and its effect on electrolyzer performance needs to be assessed. We conducted three-electrode and flow cell experiments with electrolyte Fe and Ni electrodes. Three-electrode cell experiments show that Fe ([Fe] = 6-357 μM; ICP-OES) promotes HER and OER by lowering both overpotentials by at least 100 mV at high current densities (T = 35°C-91°C). The overpotential of a zero-gap flow cell was decreased by 200 mV when increasing the Fe concentration ([Fe] = 13-549 μM, T = 21°C-75°C). HER benefits from the formation of Fe dendrite layers (SEM/EDX, XPS), which prevent NiH_x formation and increase the overall active area. The OER benefits from the formation of mixed Ni/Fe oxyhydroxides leading to better catalytic activity and Tafel slope reduction.

Keywords: Applied sciences; Electrochemistry.