Electrochemical impedance spectra of RuO2 during oxygen evolution reaction studied by the distribution function of relaxation times

Sankar, K. Vijaya; Attias, Rinat; Tsur, Yoed

doi:10.1016/j.elecom.2019.106641

Cited by 18 publications

(21 citation statements)

References 17 publications

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“…The unique yolk/shell structure of the ZIF-67@POM catalyst ensured a high electrical conductivity and fast charge transfer, which resulted in a significant reduction of the overpotential. From all of the examined ZIF-67@POM hybrids, the 6-ZIF-67@POM catalyst exhibited the smallest Tafel slope (58 mV dec −1 ) and lowest overpotential values (287, 313, and 338 mV at current densities of 10, 20, and 30 mA cm −2 , respectively), which are even comparable to those observed for RuO 2 , which is one of the most efficient and well-known electrocatalysts for the OER reaction [159].…”

Section: Electrocatalysismentioning

confidence: 76%

“…Besides the use of POM@MOF hybrids in organocatalysis, POMs also exhibit interesting electrocatalytic properties as they can undergo fast and reversible multi-electron transfers [158]. Within this context, POMs have already shown great potential in the electrochemical oxygen evolution reaction (OER) in a homogenous manner [159]. Despite the remarkable progress in this field, there are only a few reports on the encapsulation of POMs in the cages of MOFs for electrocatalytic water oxidation, as can be seen in Table 2.…”

Section: Electrocatalysismentioning

confidence: 99%

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POM@MOF Hybrids: Synthesis and Applications

et al. 2020

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The hybrid materials that are created by supporting or incorporating polyoxometalates (POMs) into/onto metal–organic frameworks (MOFs) have a unique set of properties. They combine the strong acidity, oxygen-rich surface, and redox capability of POMs, while overcoming their drawbacks, such as difficult handling, a low surface area, and a high solubility. MOFs are ideal hosts because of their high surface area, long-range ordered structure, and high tunability in terms of the pore size and channels. In some cases, MOFs add an extra dimension to the functionality of hybrids. This review summarizes the recent developments in the field of POM@MOF hybrids. The most common applied synthesis strategies are discussed, together with major applications, such as their use in catalysis (organocatalysis, electrocatalysis, and photocatalysis). The more than 100 papers on this topic have been systematically summarized in a handy table, which covers almost all of the work conducted in this field up to now.

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Section: Electrocatalysismentioning

confidence: 76%

Section: Electrocatalysismentioning

confidence: 99%

POM@MOF Hybrids: Synthesis and Applications

et al. 2020

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“…Therefore, R h decreasing with increasing overpotential indicates that the parallel model should be used, whereas an overpotential‐independent R h corresponds to the series model [36,60] . In order to verify the selected models, we applied the distribution of relaxation times (DRT) method to determine the time constant(s) from the impedance data of all electrolytes [70] . (Details can be found in Section 2.2 in Supporting Information.…”

Section: Experimental and Simulation Sectionmentioning

confidence: 99%

Understanding the Hydrogen Evolution Reaction Kinetics of Electrodeposited Nickel‐Molybdenum in Acidic, Near‐Neutral, and Alkaline Conditions

et al. 2021

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Nickel‐molybdenum (NiMo) alloys can be a possible alternative to platinum as hydrogen evolution reaction (HER) catalysts because of the superior HER activity. However, the superior HER activity and the pH‐dependent kinetics are not currently fully understood. Herein, we present a study of HER kinetics and mechanisms of NiMo in alkaline, near‐neutral and acidic media by combining voltammetry measurements with electrochemical impedance spectroscopy and a microkinetic model. The results indicate that, compared to Ni, NiMo has significantly higher active surface area and intrinsic HER activity. In the subsequent measurements, we demonstrated that different from the existing explanations to the HER mechanisms for NiMo, the HER process in acidic, near‐neutral, and alkaline media is controlled by the Heyrovsky step. Our results show that increasing pH increases the hydrogen coverage, which increases the Tafel‐slope at low overpotentials, eventually resulting in only a single Tafel slope, which would commonly be interpreted as a Volmer‐limited reaction. Furthermore, the studies of thickness effect on HER kinetics show that the HER kinetics of NiMo are thickness‐dependent. In phosphate buffer, the increase in thickness did not significantly increase the double‐layer capacitance, but simulations with the microkinetic model indicate that the active surface area still increased similarly to other electrolytes, which is likely related to the type of electrolyte used.

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“…The alternating voltage amplitude in impedance measurements was 3 mV and the frequency ranged from 100 kHz to 5 mHz. The electrochemical impedance spectroscopy data were analyzed using Impedance Spectroscopy Genetic Programing (ISGP), a matlab based program that finds the distribution function of relaxation times (DFRT) via genetic programming [ 60 , 61 , 62 ]. ISGP finds an analytical form of the DFRT, which makes it possible to follow the changes in each peak that idealy represent a process.…”

Section: Methodsmentioning

confidence: 99%

Electrochemical Activation of Li2MnO3 Electrodes at 0 °C and Its Impact on the Subsequent Performance at Higher Temperatures

et al. 2020

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This work continues our systematic study of Li- and Mn- rich cathodes for lithium-ion batteries. We chose Li2MnO3 as a model electrode material with the aim of correlating the improved electrochemical characteristics of these cathodes initially activated at 0 °C with the sstructural evolution of Li2MnO3, oxygen loss, formation of per-oxo like species (O22−) and the surface chemistry. It was established that performing a few initial charge/discharge (activation) cycles of Li2MnO3 at 0 °C resulted in increased discharge capacity and higher capacity retention, and decreased and substantially stabilized the voltage hysteresis upon subsequent cycling at 30 °C or at 45 °C. In contrast to the activation of Li2MnO3 at these higher temperatures, Li2MnO3 underwent step-by-step activation at 0 °C, providing a stepwise traversing of the voltage plateau at >4.5 V during initial cycling. Importantly, these findings agree well with our previous studies on the activation at 0 °C of 0.35Li2MnO3·0.65Li[Mn0.45Ni0.35Co0.20]O2 materials. The stability of the interface developed at 0 °C can be ascribed to the reduced interactions of the per-oxo-like species formed and the oxygen released from Li2MnO3 with solvents in ethylene carbonate–methyl-ethyl carbonate/LiPF6 solutions. Our TEM studies revealed that typically, upon initial cycling both at 0 °C and 30 °C, Li2MnO3 underwent partial structural layered-to-spinel (Li2Mn2O4) transition.

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Electrochemical impedance spectra of RuO2 during oxygen evolution reaction studied by the distribution function of relaxation times

Cited by 18 publications

References 17 publications

POM@MOF Hybrids: Synthesis and Applications

POM@MOF Hybrids: Synthesis and Applications

Understanding the Hydrogen Evolution Reaction Kinetics of Electrodeposited Nickel‐Molybdenum in Acidic, Near‐Neutral, and Alkaline Conditions

Electrochemical Activation of Li2MnO3 Electrodes at 0 °C and Its Impact on the Subsequent Performance at Higher Temperatures

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