Electrochemical impedance studies of IrO 2 catalysts for oxygen evolution

Papaderakis, Α.; Tsiplakides, D.; Balomenou, Stella; Sotiropoulos, S.

doi:10.1016/j.jelechem.2015.09.033

Cited by 83 publications

(68 citation statements)

References 41 publications

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“…The redox peak at 0.77 V originates from the oxidation of Ir III to Ir IV and the redox peak at 1.23 V originates from the oxidation of Ir IV to Ir V . 4,13,24 This corroborates the assumption that the cathode potential -at least at low current density -is close to the SHE potential.…”

Section: Discussionsupporting

confidence: 85%

Electrochemical Characterization of a PEMEC Using Impedance Spectroscopy

Elsøe

Grahl‐Madsen

Scherer³

et al. 2017

J. Electrochem. Soc.

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In this study, electrochemical impedance spectroscopy (EIS) is applied in combination with cyclic voltammetry (CV) and current density -cell voltage curves (iV-curves) to investigate the processes contributing to the total impedance of a polymer electrolyte membrane electrolysis cell (PEMEC). iV-curves were linear above 0.35 A cm −2 implying ohmic processes to be performance limiting, however the impedance spectra showed three arcs indicating three electrochemical reactions at these conditions not to be purely ohmic, but also to have capacitive properties. A hypothesis that the composite IrO x /Nafion anode catalyst layer causes two of these arcs with a constant sum of resistance and current constrictions cause the third arc, is suggested. This hypothesis implies that the total differential cell resistance at current densities above 0.35 A cm −2 is purely ascribed to protonic resistance in Nafion in this type of PEMEC. The interest in renewable electrical energy obtained from e.g. wind turbines and solar cells have increased over the past years. However, the demand of electrical energy from society does not always correlate with the renewable electrical energy production, and a method to store the excess electrical energy for later use is needed. One such method is electrolysis of water into hydrogen and thus converts electrical energy into chemical energy bound in the hydrogen molecules, and thereby the energy can be stored. PEMECs have the ability to operate at high current densities, which reduces the operation costs.

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Section: Discussionsupporting

confidence: 85%

Electrochemical Characterization of a PEMEC Using Impedance Spectroscopy

Elsøe

Grahl‐Madsen

Scherer³

et al. 2017

J. Electrochem. Soc.

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“…The actual charge transfer resistance values for Ir 0.6 Cr 0.4 O x ‐350, Ir 0.6 Cr 0.4 O x ‐450 and c‐IrO x were 51.9, 54.8 and 222.9 Ω, respectively. Among these catalysts, the Ir 0.6 Cr 0.4 O x ‐350 catalysts had the smallest charge transfer resistance, which contributed to their superior catalytic activity and greatly promoted their oxygen evolution kinetics of Ir 0.6 Cr 0.4 O x ‐350 . The electrochemical surface area (ECSA) of Ir 0.6 Cr 0.4 O x ‐350, Ir 0.6 Cr 0.4 O x ‐450 and c‐IrO x were determined by regional cyclic voltammograms (CVs) at different scan rates.…”

Section: Resultsmentioning

confidence: 99%

Iridium‐Chromium Oxide Nanowires as Highly Performed OER Catalysts in Acidic Media

et al. 2019

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The oxygen evolution reaction (OER) severely restricts the efficiency of electrolyzers due to its sluggish kinetics. In particular, only a few OER electrocatalysts, such as expensive and scarce iridium (Ir)-based materials, have been developed to function in acidic media. Therefore, the exploration of efficient and stable electrocatalysts with decreased precious metal content for the OER in acid is desired. Herein, chromium (Cr)incorporated IrO x solid solution nanowires not only exhibit high catalytic activity with a low overpotential of 250 mV at 10 mA cm À 2 , but also display robust catalytic performance without a decay in activity throughout 25 h of testing at 10 mA cm À 2 in 0.5 M H 2 SO 4 . This improved catalytic performance for the Cr-incorporated IrO x electrocatalysts is ascribed to an abundance of exposed active sites, tuned electronic states, optimized binding energy for intermediates on the catalyst surface and the consequent facile reaction kinetics.

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“…[38][39][40] Figure 8a shows the plot of Tafel slopes of the synthesized materials. [41][42][43] R S and R CT values of RuO 2 /CC, Cu 2 CoS z /CC, CuCoS z / CC, CuCo 2 S z /CC, and CuCo 3 S z /CC are summarized in Table 2. It is clearly visible from Table 2 that CuCo 3 S z /CC electrocatalyst has the lowest Tafel slope value, which indicates better electrocatalytic activity in comparison with other electrocatalysts.…”

Section: Electrocatalytic Activitymentioning

confidence: 99%

“…The data are fitted with the equivalent circuit that comprises of solution resistance (R S ), charge transfer resistance (R CT ), and constant phase element (CPE). [41][42][43] R S and R CT values of RuO 2 /CC, Cu 2 CoS z /CC, CuCoS z / CC, CuCo 2 S z /CC, and CuCo 3 S z /CC are summarized in Table 2. R CT value plays a vital role in controlling the electrocatalytic activity.…”

Section: Electrocatalytic Activitymentioning

confidence: 99%

Development of Copper Cobalt Sulfide with Cu : Co Ratio Variation on Carbon Cloth as an Efficient Electrode Material for the Oxygen Evolution Reaction

Mahala

Sharma

et al. 2019

ChemElectroChem

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When designing a device for energy conversion, development of a highly active catalyst for OER (oxygen evolution reaction) reaction in alkaline medium is of utmost importance. For energy conversion, herein, we developed copper cobalt sulfide on carbon cloth (CC) using a simple and facile hydrothermal method. A vertically grown 2D sheet-like structure of coppercobalt sulfide is observed using L-cysteine as a sulfur source. An optimized ratio of copper(II) and cobalt(III) and the best sulfur source are found to boost the electrocatalytic activity of mixed metal thiospinel for OER. Several characterization techniques (XRD, Raman, FESEM, TEM, XPS, and ICP-AES) were used to confirm phase purity, morphology, and composition of copper cobalt sulfides. We have established that 2D nanosheets of CuCo 3 S z /CC exhibited superior electrocatalytic performance over bare RuO 2 in 1.0 M KOH solution. It is observed that CuCo 3 S z /CC need only 105 mV overpotential to generate 5 mA/ cm 2 current density. CuCo 3 S z /CC is very stable and able to produce unaltered current density under an applied potential of 1.615 V vs. RHE for 48 h. Electrochemically active surface area calculation is performed for all catalysts to confirm higher electrocatalytic activity. The catalyst, CuCo 3 S z /CC is used in a broad pH region using 0.5 M KOH, saline water, and 0.5 M Na 2 SO 4 electrolyte solution to widen the applicability of water splitting. This work shows an avenue to develop active and durable electrocatalyst for OER without using any noble metal electrocatalyst.[a] C.

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Electrochemical impedance studies of IrO 2 catalysts for oxygen evolution

Cited by 83 publications

References 41 publications

Electrochemical Characterization of a PEMEC Using Impedance Spectroscopy

Electrochemical Characterization of a PEMEC Using Impedance Spectroscopy

Iridium‐Chromium Oxide Nanowires as Highly Performed OER Catalysts in Acidic Media

Development of Copper Cobalt Sulfide with Cu : Co Ratio Variation on Carbon Cloth as an Efficient Electrode Material for the Oxygen Evolution Reaction

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