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Observing the oxidation state turnover in heterogeneous iridium-based water oxidation catalysts

2014; Royal Society of Chemistry; Volume: 5; Issue: 9 Linguagem: Inglês

10.1039/c4sc00975d

2041-6539

Alessandro Minguzzi, Ottavio Lugaresi, Elisabetta Achilli, C. Locatelli, Alberto Vertova, Paolo Ghigna, Sandra Rondinini,

Copper-based nanomaterials and applications

In this work the oxidation states assumed by Ir in oxide systems used as heterogeneous catalysts for water oxidation are determined by means of in situ X-ray Absorption Spectroscopy (XAS). Using a highly hydrated iridium oxide film allows the maximum number of Ir sites to be involved in the electrochemical processes occurring at the catalysts during water oxidation (oxygen evolution reaction, OER). X-ray Absorption Near Edge Structure (XANES) spectra clearly indicate the co-existence of Ir(III) and Ir(V) at the electrode potentials where OER occurs. This represents a fundamental step both in the understanding of the water oxidation mechanism catalysed by heterogeneous Ir oxide systems, and in the possible tailoring of electrocatalysts for OER.