Voltammetric characterization of an iridium oxide-based system: the pseudocapacitive nature of the Ir0.3Mn0.7O2 electrode

Abstract

Mixtures of IrO 2 '/MnO 2 (30:70 mol%) have been electrochemically studied by cyclic voltammetry (CV) in acid solution. The crystalline structure, morphology and the electrochemical properties of the electrodes have been studied as a function of the annealing temperature. X-ray diffraction analysis (XRD), show absence of Mn 2 O 3 phase formation and suggest the possible of formation of a solid solution of IrO 2 and MnO 2 mainly between 400 and 450 8C. The voltammetric behavior depends on the potential cycle number and annealing temperature employed in the preparation of the oxide layer. A good potential window in aqueous H 2 SO 4 and high electroactive area are obtained due to the contribution of Ir redox transitions. Energy-dispersive X-ray (EDX) and scanning electron microscopy (SEM) analysis suggest an enrichment of the Ir content on the surface at the cost of the dissolution of the manganese present in the film when the electrode is submitted to the continuous potential scan. The electrodes have been found to perform well in electrochemical capacitor applications with a specific capacitance close to 550 F g (1. The large capacitance exhibited by this system arises from a combination of the double-layer capacitance and pseudocapacitance associated with surface redox-type reactions.

Electrochemical impedance studies of IrO 2 catalysts for oxygen evolution

“…ACCEPTED MANUSCRIPT 8 reproducibility of all electrochemical impedance data confirmed by the comparison of consecutive measurements at the same dc potential.…”

“…The electrochemical applications of iridium dioxide span a wide range, from electrochromic materials [1,2] and pH-sensors [3,4] to supercapacitors [5][6][7][8] and oxygen evolving anodes [9][10][11][12]. Since IrO 2 electrodes show good activity and high stability for the oxygen evolution reaction (OER), they are candidates for anode components of water electrolysers and regenerative fuel cells [13][14][15][16].…”

“…C t can be taken as a measure of the catalyst electroactive surface area and the product R ct C t (where R ct is the OER charge transfer/polarization resistance) as the appropriate parameter to characterise the catalyst intrinsic catalytic activity. C t can also be used to correct direct current vs. electrode potential OER data for electroactive surface area effects.The electrochemical applications of iridium dioxide span a wide range, from electrochromic materials [1, 2] and pH-sensors [3,4] to supercapacitors [5][6][7][8] and oxygen evolving anodes [9][10][11][12]. Since IrO 2 electrodes show good activity and high stability for the oxygen evolution reaction (OER), they are candidates for anode components of water electrolysers and regenerative fuel cells [13][14][15][16].…”

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

“…Moreover, IrO 2 -based oxides have been recently investigated as energy storage materials [21] and as electrocatalysts for oxygen reduction reaction (ORR) [22][23][24], hydrogen evolution reaction (HER) [25][26][27] and electrooxidation of organic pollutants [28,29].…”

Nanostructured Coatings for Improved Charge Delivery to Neurons

“…Examples of such reactions include the oxide formation of platinum (Pt) or iridium (Ir) and the valence transitions between different forms of iridium oxides. Electrodes with reversible faradic charge transfer capabilities are said to have pseudocapacitive properties, as the mode of charge injection is through mass transfer (as in faradic reactions), but the electrode material is preserved as in the case of capacitive charge transfer [87][88][89][90] (Fig. 4.4c).…”