Issue 14, 2018

Highly active nano-sized iridium catalysts: synthesis and operando spectroscopy in a proton exchange membrane electrolyzer

Abstract

A stable and cost effective oxygen evolution reaction (OER) catalyst is crucial for the large-scale market penetration of proton exchange membrane (PEM) water electrolyzers. We show that the synthesis of iridium nanoparticles in either low purity ethanol or water, or in the absence of a surfactant, is detrimental to the electrocatalytic properties of the materials. Adding NaBH4 in excess improves the purity of the catalyst enhancing the OER activity up to 100 A gIr−1 at 1.51 V vs. RHE, the highest value reported so far for high purity Ir nanoparticles. The measured OER activity correlates with the capacitive current rather than with the charge corresponding to the IrIII/IrIV oxidation peak. Operando near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) on membrane electrode assemblies (MEAs) with the synthesized catalysts reveals a metallic core surrounded by a thin layer of IrIII/IV oxides/hydroxides. Oxidation of IrIII leaves behind a porous ultrathin layer of IrIV oxides/hydroxides, which dominate the surface during the OER, while IrV was not detected.

Graphical abstract: Highly active nano-sized iridium catalysts: synthesis and operando spectroscopy in a proton exchange membrane electrolyzer

Supplementary files

Article information

Article type
Edge Article
Submitted
02 feb 2018
Accepted
20 feb 2018
First published
20 feb 2018
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2018,9, 3570-3579

Highly active nano-sized iridium catalysts: synthesis and operando spectroscopy in a proton exchange membrane electrolyzer

P. Lettenmeier, J. Majchel, L. Wang, V. A. Saveleva, S. Zafeiratos, E. R. Savinova, J.-J. Gallet, F. Bournel, A. S. Gago and K. A. Friedrich, Chem. Sci., 2018, 9, 3570 DOI: 10.1039/C8SC00555A

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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