Electrochemical deposition and characterization of iridium oxide films on Ti 2 AlC support for oxygen evolution reaction
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ORIGINAL PAPER
Electrochemical deposition and characterization of iridium oxide films on Ti2AlC support for oxygen evolution reaction N. R. Elezović 1 & P. Zabinski 2 & U. Č. Lačnjevac 1 & M. N. Krstajić Pajić 3 & V. D. Jović 1 Received: 29 May 2020 / Revised: 31 August 2020 / Accepted: 2 September 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Two types of iridium oxide films formed at the Ti2AlC substrate were investigated: (1) anodically electrodeposited iridium oxide film from the solution based on IrCl3xH2O; (2) iridium oxide film prepared by cycling thin layer of electrodeposited Ir in the 0.5 M H2SO4 from − 0.25 to 1.20 V. It was shown that during anodic electrodeposition of iridium oxide film (1) coulombic efficiency decreases with increasing anodic potential, being only 3% at E = 0.7 V vs. SCE and 26% at E = 0.62 V vs. SCE. A pair of peaks corresponding to the transition Ir(III)-oxide/Ir(IV)-oxide was present on the CVs recorded in 0.5 M H2SO4. While cycling pure Ir thin layer in the solution of 0.5 M H2SO4 from − 0.25 to 1.20 V (2) up to 100 cycles, typical CV response was characterized with the prepeak and a pair of peaks corresponding to the Ir(III)/Ir(IV)-oxide transition. With the increase of cycles number to 150, additional peak at potential of 1.0 V appeared. This peak was formed on the account of pair of peaks corresponding to the Ir(III)/Ir(IV)-oxide transition. The oxygen evolution reaction (OER) was investigated at both iridium oxide films. It was shown that the Tafel slope for the OER was ~ 40 mV dec−1 for the first polarization curve, confirming that the rds was a reaction S–OH → S–Oads + H+ + e−. As the number of recorded polarization curves increased, the activity of both types of iridium oxide films decreased, due to dissolution of iridium oxide films at the potentials of the OER. It is shown that anodically electrodeposited iridium oxide film is more active for the OER than that obtained by cycling electrodeposited iridium layer. However, both iridium oxide films exhibited insufficient stability.
Introduction
Anodically electrodeposited iridium oxide films
Iridium oxide (IrOx) films could be obtained by two electrochemical procedures: (1) anodic electrodeposition from the solution containing IrCl3 or IrCl4 of pH 10.5; (2) cycling of pure Ir from the potential of hydrogen evolution to the potential of oxygen evolution.
Anodically electrodeposited iridium oxide films were mainly investigated for applications as electrochromic devices [1–3], as pH electrode sensors [4–7], and as anodes in polymer electrolyte membrane water electrolysis (PEMWE) [8–11]. Few papers were devoted to the activity of iridium oxide towards the OER and its stability during the OER [12–15].
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10008-020-04816-7) contains supplementary material, which is available to authorized users. * N. R. Elezović [email protected] 1
Institute for Multidisciplinary Research University of Belgrade, Knez
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