Iridium oxide-based nanocrystalline particles as oxygen evolution electrocatalysts

Marshall, A.; Børresen, B.; Hägen, G.; Sunde, Svein; Tsypkin, Mikhail; Tunold, R.

doi:10.1134/s1023193506100223

Cited by 62 publications

(59 citation statements)

References 17 publications

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“…In PEM electrolysers, electrode coatings are generally pre-prepared particles, applied as an ''ink'' to the membrane to ensure both good contact between the electrocatalytic layer and the solid membrane electrolyte, and a viable route for the reactant access and the gaseous products removal [7,8].…”

Section: Introductionmentioning

confidence: 99%

Physico-chemical characterization of IrO2–SnO2 sol-gel nanopowders for electrochemical applications

et al. 2009

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Mixed tin-iridium oxide (Sn 0.85 Ir 0.15 O 2 ) nanoparticles at low Ir content (15 mol%) were prepared by the sol-gel preparative route, varying calcination temperatures in the range 450-550°C. The crystal structures, the phase composition and crystallite sizes were analyzed by X-ray powder diffraction (XRD). The local order of the materials was investigated by Raman spectroscopy. X-ray photoelectron spectroscopy (XPS) analysis revealed the variation of the Ir surface state with the temperature of firing. The morphology of crystallites and the aggregates were analyzed by high resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM), respectively. Nitrogen physisorption by BET method was adopted to evaluate the particle surface area and the mesopore volume distribution. Electrochemical properties of the Ti-supported powders were evaluated by cyclic voltammetry (CV) and quasi steady-state voltammetry.

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Section: Introductionmentioning

confidence: 99%

Physico-chemical characterization of IrO2–SnO2 sol-gel nanopowders for electrochemical applications

et al. 2009

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“…[2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] In addition, some theoretical studies, at different levels of theory, have confirmed the structural results of the experiments, showing enhanced stability of the rutile phase for most metal dioxides. [20][21][22][23] Rutile oxides are interesting in connection with electrochemical and photoelectrochemical water splitting, [24][25][26][27] and recently the surface redox processes on, e.g., RuO 2 and TiO 2 have been treated using density functional theory ͑DFT͒. 28,29 The question remains whether standard DFT-generalized gradient approximation ͑GGA͒ ͑Refs.…”

Section: Introductionmentioning

confidence: 99%

Formation energies of rutile metal dioxides using density functional theory

et al. 2009

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We apply standard density functional theory at the generalized gradient approximation ͑GGA͒ level to study the stability of rutile metal oxides. It is well known that standard GGA exchange and correlation in some cases is not sufficient to address reduction and oxidation reactions. Especially the formation energy of the oxygen molecule and the electron self-interaction for localized d and f electrons are known shortcomings. In this paper we show that despite the known problems, it is possible to calculate the stability of a wide range of rutile oxides MO 2 , with M being Pt, Ru, Ir, Os, Pb, Re, Mn, Se, Ge, Ti, Cr, Nb, W, Mo, and V, using the electrochemical series as reference. The mean absolute error of the formation energy is 0.29 eV using the revised Perdew-Burke-Ernzerhof ͑PBE͒ GGA functional. We believe that the reason for the success is due to the reference level being H 2 and H 2 O and not O 2 and due to a more accurate description of exchange for this particular GGA functional compared to PBE. Furthermore, we would expect the self-interaction problem to be largest for the most localized d orbitals; that means the late 3d metals and since Co, Fe, Ni, and Cu do not form rutile oxides they are not included in this study. We show that the variations in formation energy can be understood in terms of a previously suggested model separating the formation energy into a metal deformation contribution and an oxygen binding contribution. The latter is found to scale with the filling of the d band.

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“…1 is relevant as a material for electrochromics, [2][3][4] electrocatalysis [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] and as a pH sensor. 20 A proposed mechanism for the electrochromic properties of the material based on the electronic structure was suggested by Granqvist.…”

Section: Iridium Oxidementioning

confidence: 99%

Electronic Structure and Growth of Electrochemically Formed Iridium Oxide Films

Ilyukhina

Sunde

Haverkamp

2017

J. Electrochem. Soc.

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The nature of the electronic structure of electrochemically formed iridium oxide films (EIROF) is investigated by in-situ conductivity measurements in an electrochemical cell and ex-situ current-sensing atomic force microscopy (CS-AFM). A direct demonstration of changes in the conductivity for electrochemically formed iridium oxide films (EIROF) with the applied potential of EIROF electrodes in an electrochemical cell is presented. The in-situ conductivity shows a single step-like change at a potential of approximately 1.2 V in 0.5 mol dm −3 H 2 SO 4 vs. a reversible hydrogen reference electrode. The change in conductivity is also reflected in results of ex-situ CS-AFM for EIROF electrodes emersed at different potentials. At an emersion potential of 0 V the CS-AFM currentvoltage characteristics are non-linear and similar to those of diodes. At an emersion potential of 1.6 V the CS-AFM current-voltage characteristics are approximately linear, consistent with metallic behavior. Mott-Schottky analysis shows that at low potentials the oxide behaves as a p-type semiconductor with a flatband potential approximately 500 mV below the transition to high conductivity from the in-situ conductivity measurements. These results allow for an interpretation of changes in the relative magnitudes of the III/IV and IV/V (or IV/VI) voltammetric peaks during film growth through a block-release behavior involving space-charge layers in the oxide. Iridium oxide 1 is relevant as a material for electrochromics, 2-4 electrocatalysis 5-19 and as a pH sensor. 20 A proposed mechanism for the electrochromic properties of the material based on the electronic structure was suggested by Granqvist. 3,4 According to this explanation the change of color with potential is due to variations in band filling associated with intercalation of protons and possibly other ions,where A − is a solution anion, and h • and electron hole. For oxygen-evolution electrocatalysts one expects the activity to depend on the binding energy of intermediates involved in the reaction according to the Sabatier principle. Since the binding energy of the various relevant intermediates appear to scale with the binding energy of oxygen, the latter quantity may serve as a descriptor of catalytic activity for the oxygen evolution reaction. Exactly how the features of the electronic structure of the catalyst are related to the binding energy appears to be less clear than in the case of metals for which the d-band theory and its refinements 22,23 appear to successfully rationalize electronic structure and (electro-) catalytic behavior. Recent work indicates that the number of electrons in the d-band of transition metal oxides is an important descriptor of catalytic activity, 24,25 although other aspects of the electronic structure may be important as well. 26Also other electrochemical properties such as the shapes of voltammograms have been attempted analyzed in terms of electronic structure. 27It is therefore of interest to characterize properties reflecting the electronic struct...

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Iridium oxide-based nanocrystalline particles as oxygen evolution electrocatalysts

Cited by 62 publications

References 17 publications

Physico-chemical characterization of IrO2–SnO2 sol-gel nanopowders for electrochemical applications

Physico-chemical characterization of IrO2–SnO2 sol-gel nanopowders for electrochemical applications

Formation energies of rutile metal dioxides using density functional theory

Electronic Structure and Growth of Electrochemically Formed Iridium Oxide Films

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