Iridium Oxide Coatings with Templated Porosity as Highly Active Oxygen Evolution Catalysts: Structure‐Activity Relationships. Issue 11 (8th May 2015)

• Record Type: Journal Article
• Authors: Bernicke, Michael; Ortel, Erik; Reier, Tobias; Bergmann, Arno; Ferreira de Araujo, Jorge; Strasser, Peter; Kraehnert, Ralph
• Is Part Of: ChemSusChem. Volume 8:Issue 11(2015:Jun.)
• Page Start: 1908
• Page End: 1915
• Publication Date: 2015-05-08
• Subjects: Green chemistry -- Periodicals; Sustainable engineering -- Periodicals; Chemistry -- Periodicals; Chemical engineering -- Periodicals; 660
• DOI: 10.1002/cssc.201402988
• Languages: English
• ISSNs: 1864-5631

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>Iridium oxide is the catalytic material with the highest stability in the oxygen evolution reaction (OER) performed under acidic conditions. However, its high cost and limited availability demand that IrO₂ is utilized as efficiently as possible. We report the synthesis and OER performance of highly active mesoporous IrO₂ catalysts with optimized surface area, intrinsic activity, and pore accessibility. Catalytic layers with controlled pore size were obtained by soft‐templating with micelles formed from amphiphilic block copolymers poly(ethylene oxide)‐<italic>b</italic>‐poly(butadiene)‐<italic>b</italic>‐poly(ethylene oxide). A systematic study on the influence of the calcination temperature and film thickness on the morphology, phase composition, accessible surface area, and OER activity reveals that the catalytic performance is controlled by at least two independent factors, that is, accessible surface area and intrinsic activity per accessible site. Catalysts with lower crystallinity show higher intrinsic activity. The catalyst surface area increases linearly with film thickness. As a result of the templated mesopores, the pore surface remains fully active and accessible even for thick IrO₂ films. Even the most active multilayer catalyst does not show signs of transport limitations at current densities as high as 75 mA cm⁻².</p> </abstract>