Oxygen Evolution Reaction at IrO2/Ir(Ni) Film Electrodes Prepared by Galvanic Replacement and Anodization: Effect of Precursor Ni Film Thickness.

Aikaterini Touni,Athanasios Papaderakis,Sotiris Sotiropoulos,Georgios Vourlias,Dimitrios Karfaridis

doi:10.3390/molecules24112095

Abstract

IrO2/Ir(Ni) film electrodes of variable Ni content have been prepared via a galvanic replacement method, whereby surface layers of pre-deposited Ni are replaced by Ir, followed by electrochemical anodization. Electrodeposition of Ni on a glassy carbon electrode support has been carried out at constant potential and the charge of electrodeposited Ni controlled so as to investigate the effect of precursor Ni layer thickness on the electrocatalytic activity of the corresponding IrO2/Ir(Ni)/GC electrodes for the oxygen evolution reaction (OER). After their preparation, these electrodes were characterized by microscopic (SEM) and spectroscopic (EDS, XPS) techniques, revealing the formation of Ir deposits on the Ni support and a thin IrO2 layer on their surfaces. To determine the electroactive surface area of the IrO2 coatings, cyclic voltammograms were recorded in the potential range between hydrogen and oxygen evolution and the charge under the anodic part of the curves, corresponding to Ir surface oxide formation, served as an indicator of the quantity of active IrO2 in the film. The electrocatalytic activity of the coatings for OER was investigated by current–potential curves under steady state conditions, revealing that the catalysts prepared from thinner Ni films exhibited enhanced electrocatalytic performance.

Highlights

The oxygen evolution reaction (OER) is relevant to many practical applications such as the electrolytic production of H2 and in processes that Dimensionally Stable Anodes (DSAs) are required.Materials with high stability and electrocatalytic activity for OER are sought [1]
OER anodes based on Ir have been developed using Ni [5,6] as an additional component since Ni has been reported to improve the electrocatalytic performance of IrO2 for OER [1,5,7,8]
SEM micrographs depict the morphology of the catalyst surface and, combined with EDS analysis, confirm the presence of Ir deposits on Ni

Summary

Introduction

Materials with high stability and electrocatalytic activity for OER are sought [1]. These are composed of electrocatalytic active metal oxides on inert and stable substrates [2], replacing precious metals in their bulk form, which are no longer used in industrial applications [2,3]. Ni and Co single or mixed oxide or sulfide compounds are known to show increased OER activity in alkaline media [9,10,11] and this is attributed to their high conductivity and electrochemical stability as well as to synergistic interactions between catalyst components

Methods

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Conclusion