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

Lettenmeier, Philipp and Majchel, Jan and Wang, Li and Saveleva, Viktoriia and Zaferiatos, Spiros and Savinova, Elena and Gallet, Jean-Jacques and Bournel, Fabrice and Gago, Aldo and Friedrich, K. Andreas (2018) Highly active nano-sized iridium catalysts: synthesis and operando spectroscopy in a proton exchange membrane electrolyzer. Chemical Science. Royal Society of Chemistry. ISSN 2041-6520

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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.

Item URL in elib:https://elib.dlr.de/125220/
Document Type:Article
Title:Highly active nano-sized iridium catalysts: synthesis and operando spectroscopy in a proton exchange membrane electrolyzer
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Lettenmeier, PhilippPhilipp.Lettenmeier (at) dlr.dehttps://orcid.org/0000-0002-2822-8440
Majchel, JanJan.Majchel (at) dlr.deUNSPECIFIED
Wang, LiLi.Wang (at) dlr.deUNSPECIFIED
Saveleva, Viktoriiaviktoriia.SAVELEVA (at) etu.unistra.frUNSPECIFIED
Zaferiatos, Spirosspiros.zafeiratos (at) unistra.frUNSPECIFIED
Savinova, Elenaelena.savinova (at) unistra.frUNSPECIFIED
Gallet, Jean-Jacquesjean-jacques.gallet (at) upmc.frUNSPECIFIED
Bournel, Fabricefabrice.bournel (at) upmc.frUNSPECIFIED
Gago, Aldoaldo.gago (at) dlr.deUNSPECIFIED
Friedrich, K. Andreasandreas.friedrich (at) dlr.deUNSPECIFIED
Date:2 February 2018
Journal or Publication Title:Chemical Science
Refereed publication:Yes
Open Access:Yes
Gold Open Access:Yes
In SCOPUS:Yes
In ISI Web of Science:Yes
Publisher:Royal Society of Chemistry
ISSN:2041-6520
Status:Published
Keywords:PEM Electrolysis, NAP-XPS, Iridium catalyst, CCM, MEA, Anode, Operando XPS analysis
HGF - Research field:Energy
HGF - Program:Storage and Cross-linked Infrastructures
HGF - Program Themes:Electrolysis and Hydrogen
DLR - Research area:Energy
DLR - Program:E SP - Energy Storage
DLR - Research theme (Project):E - Elektrochemical Processes (Electrolysis)
Location: Stuttgart
Institutes and Institutions:Institute of Engineering Thermodynamics > Electrochemical Energy Technology
Deposited By: Gago, Aldo
Deposited On:20 Dec 2018 14:52
Last Modified:20 Dec 2018 14:52

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