Redox Reaction Of Ferrocene Research Articles

Monitoring the Solid-Electrolyte Interphase Formation in Bis(fluorosulfonyl)Amide Ionic Liquid Electrolyte Using a Redox Probe Method

The solid-electrolyte interphase (SEI) has been considered to be formed on the negative electrode surface by reductive decomposition of electrolyte components. In the case of the electrolytes containing lithium ions, the SEI can be regarded as the Li+ conductor that enables the negative electrode reactions and prevents the further decomposition of the electrolytes. The structure of the SEI is often explained by the mosaic model, in which the SEI is a composite of several different inorganic and organic domains [1]. On the other hand, we have proposed the formation of the gelled SEI in bis(fluorosulfonyl)amide (FSA–) ionic liquid electrolytes containing a high concentration of LiFSA [2,3]. Furthermore, we have reported that the SEI formation can be detected by monitoring the redox reaction of ferrocene (Fc) and ferrocenium (Fc+) [4,5]. In the present study, the time-dependent transition of the SEI formed on a Pt electrode was investigated by the redox probe method in BMPFSA (BMP+ = 1-butyl-1-methylpyrrolidinium) containing LiFSA.The formation of SEI by holding a Pt electrode at a negative potential was confirmed by a shift in the anodic peak potential of the cyclic voltammogram for Fc+/Fc couple in LiFSA/BMPFSA. The anodic peak disappeared when the electrode was held at the negative potential for a few hours, indicating the formation of a thick SEI. However, the anodic peak was observed again after keeping the electrode at the open circuit potential for a few hours, indicating the disappearance of the SEI. These results suggest that the SEI is formed by dissolution and/or dispersion of the decomposed products, which form at the electrode surface and diffuse into the electrolyte. Thus, the SEI formed at the potential is considered to exist as a metastable phase in the balance between the formation and diffusion of the decomposition products. This work was partly supported by GteX Program Japan Grant Number JPMJGX23S0.[1] E. Peled, D. Golodnitsky, and G. Ardel, J. Electrochem. Soc., 144, L208 (1997).[2] R. Furuya, T. Hara, T. Fukunaga, K. Kawakami, N. Serizawa, and Y. Katayama, J. Electrochem. Soc., 168, 100516 (2021).[3] N. Serizawa, R. Yamashita, and Y. Katayama, J. Phys. Chem. C, 127, 10434 (2023).[4] S. Kato, N. Serizawa, and Y. Katayama, J. Electrochem. Soc., 169, 076509 (2022).[5] S. Kato, N. Serizawa, and Y. Katayama, J. Electrochem. Soc., 170, 056504 (2023).

Solid-Electrolyte Interphase Formation in Amide-Type Ionic Liquids in the Presence of Different Metal Cations

The formation of solid-electrolyte interphase (SEI) on a glassy carbon (GC) electrode in 1-butyl-1-methylpyrrolidinium bis(fluorosulfonyl)amide (BMPFSA) and 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide (BMPTFSA) containing Li+, Na+, K+, and Ni2+ was investigated using the redox reaction of ferrocene (Fc). The anodic peak potential (E pa) for the oxidation of Fc changed after holding the electrode at –1.4 to –1.5 V vs Ag|Ag(I) in BMPFSA in the presence of the alkali metal ions. The decomposition of FSA– was confirmed by X-ray photoelectron spectroscopy (XPS) on a GC electrode held at –1.5 V vs Ag|Ag(I) for 6 h in BMPFSA containing the alkali metal ions. The change in E pa may also suggest the formation of homogeneous SEI in the FSA–-type ionic liquid. Moreover, E pa changed after holding the electrode at the potential more negative than –0.9 V vs Ag|Ag(I) in 50 mM Ni(TFSA)2/BMPTFSA while the decomposition of TFSA– was not confirmed by XPS on the electrode held at –1.1 V vs Ag|Ag(I) for 6 h, suggesting the bonds except C-F (e.g., S-C) were dissociated to form the SEI. Since the deposition potential of Ni in BMPTFSA was more negative than the SEI formation potential, the deposition of Ni may be inhibited by the SEI.

Redox-Copolymers for Nanofiltration-Enabled Electrodialysis

Robust, energy-efficient separation technologies for desalination and the removal of organic contaminants are critical in addressing growing concerns about water shortage and water pollution. Here, we propose a generalized strategy for advancing electrodialysis technologies using redox-flow concepts, by implementing a water-soluble redox-copolymer, poly(ferrocenylpropylmethacrylamide-co-[2-(methacryloyloxy)ethyl]trimethylammonium chloride), P(FPMAm-co-METAC), to eliminate the need for anion-exchange membranes (AEMs) and deploy cheaper and more robust nanofiltration membranes (NFs). The effective membrane retention of the redox material and stable redox activity facilitate the continuous desalination of various source waters, including brackish water, seawater, and wastewater, to produce potable water and remove organic contaminants without membrane fouling or polymer crossover. Leveraging the reversible redox reaction of ferrocene reduces energy consumption by 88% within a single-unit cell compared to conventional ED. In addition, utilizing reusable redox-copolymer and cost-effective NFs promotes economic feasibility, achieving a water production cost of $0.13 m–3. Overall, the combination of redox-copolymer in flow and NFs provides a new avenue to address water contamination caused by organic pollutants and water scarcity in an energy efficient manner.

Communication—Determination of the Formation Potential of Solid-Electrolyte Interphase in Amide-Type Ionic Liquids Containing Lithium Salts

The formation potentials of solid-electrolyte interphase (SEI) were investigated in 1-butyl-1-methylpyrrolidinium bis(fluorosulfonyl)amide (BMPFSA) and 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide (BMPTFSA) containing LiFSA and LiTFSA, respectively, by monitoring the redox reaction of ferrocene with high sensitivity. The SEI was found to affect the electrode kinetics of the outersphere electron transfer reaction. The SEIs with the thickness of less than a few nm formed in LiFSA/BMPFSA and LiTFSA/BMPTFSA at 2.4 and 2.5 V vs Li∣Li(I), respectively. The cathodic decomposition of FSA– and TFSA– was considered to be promoted by the interaction with Li+ based on the ab-initio calculation.

Effect of Additives on the Interfacial Degradation Phenomena of LiNi0.5Mn1.5O4 Thin-Film Electrodes

LiNi0.5Mn1.5O4 shows promise as a positive electrode material for lithium-ion batteries. However, because the material has a higher operating potential than conventional cathodes, interfacial side reactions are accelerated during cycling, which degrades the outmost surface of the material. Although it has been reported that some additives offer effective protection against degradation, their protection mechanism has not been clarified in detail. Here, the effect of additives on the surface states of LiNi0.5Mn1.5O4 was investigated using thin film model electrodes. It was found that surface film was not formed on LiNi0.5Mn1.5O4 in additive-free electrolyte solution even after cycling at 55 °C, and severe dissolution of transition metal ions continuously occurred, leading to rapid capacity fading. Addition of ethylene glycol bis(propionitrile) ether (EGBE) effectively suppressed the capacity fading at 55 °C. Analysis with redox reaction of ferrocene on the electrodes, X-ray photoelectron spectroscopy, and scanning electron microscopy indicated that surface film hardly formed in EGBE-containing solution, but the dissolution was effectively suppressed. Because a nitrile group tends to adsorb on positive active material at high potential, it was concluded that the adsorption layer of EGBE impeded side reactions at the interface, resulting in improved cycleability of LiNi0.5Mn1.5O4.

A portable digital-control electrochemical system with automatic ohmic drop compensation for fast scan voltammetry and its application to ultrasensitive detection of chromium(III)

In this work, a portable digital-control electrochemical system with automatic ohmic drop compensation for fast scan voltammetry was developed. The whole system consists of waveform generator module, detection module, power management module, display module, WiFi module and keying module, and it is digitally controlled. Based on the positive feedback technology and the control of microcontroller, ohmic drop could be 100% compensated automatically. Performance and behavior of this system are tested with dummy cells and an actual electrochemical cell using the redox reaction of ferrocene as a model, it was found that the highest scan rate 400 V/s could be achieved. And, it was applied to ultrasensitive detection of chromium(III), with a limit of detection of 0.3 pmol/L. In addition, it is portable because of light weight and small volume. Thus, this portable digital-control electrochemical system with automatic ohmic drop compensation opens the avenue for extensive research and application of fast scan voltammetry, especially in the construction of ultrasensitive sensors.

Characterization of the Interface between LiMn<sub>2</sub>O<sub>4</sub> Thin-film Electrode and LiBOB-based Electrolyte Solution by Redox Reaction of Ferrocene

Characterization of the Interface between LiMn<sub>2</sub>O<sub>4</sub> Thin-film Electrode and LiBOB-based Electrolyte Solution by Redox Reaction of Ferrocene

Investigation of the Surface State of LiCoO2 Thin-Film Electrodes Using a Redox Reaction of Ferrocene

One of the reasons of performance deterioration of lithium-ion batteries is the degradation of positive electrode materials. In this study, the degradation mechanism of LiCoO2 was investigated focusing on the surface electron conductivity of LiCoO2. The surface electron conductivity change in LiCoO2 thin-film electrode was investigated using a redox reaction of ferrocene. After charge-discharge cycles, the surface electron conductivity of the LiCoO2 thin-film electrode was increased and this indicates that the electron insulating surface film was not formed and lithium-ion deficit phase Li1-xCoO2 was rapidly formed at the surface region at the 1st cycle. It is found that the use of the redox reaction of ferrocene is useful to evaluate the surface state change in LiCoO2.

Investigation of LiMn2O4 Thin-Film Electrode Using Redox Reaction of Ferrocene

Introduction Lithium-ion batteries (LIBs) have been expected as the power supplies of electric vehicles (EVs). LiMn2O4 is widely desired as the positive active materials for EVs-use, However, LiMn2O4 suffer from severe degradation at elevated temperature, leading to poor cycleability of LIBs. One of the factors of degradation is formation of surface film. The surface film might bring passivation of the electrode, however, detailed properties of the surface film were not fully understood. In this study, we investigated passivation behavior of LiMn2O4using redox reaction of ferrocene. Experimental LiMn2O4 thin-film electrode was prepared by pulsed laser deposition. Three-electrode cell was used for electrochemical measurements of LiMn2O4 thin-film electrode. Lithium-ion de-intercalation/intercalation was conducted in 1 mol dm-3 LiPF6/propylene carbonate (PC) by cyclic voltammetry (0.1 mV s-1, 3.5 – 4.2 V vs. Li+/Li.). Before and after the lithium-ion de-intercalation/intercalation process, redox reaction of ferrocene was measured in 1 mol dm-3 LiClO4/PC containing 1 mmol dm-3 ferrocene by cyclic voltammetry (10 mV s-1, 3.0 – 3.6 V vs. Li+/Li.). Results and discussion Figure 1 shows cyclic voltammograms (CVs) of LiMn2O4 thin-film electrode at room temperature. Around 4.0 and 4.2 V, reversible peaks of lithium-ion de-intercalation/intercalation, which are characteristic of LiMn2O4, were observed. As the cycle number increased, peak currents gradually decreased. It indicated degradation of LiMn2O4 proceeded during cycling test. Figure 2 shows the CVs of redox reaction of ferrocene on LiMn2O4 thin-film electrode before and after the cycling process of lithium-ion de-intercalation/intercalation. Reversible redox peaks of ferrocene were observed before the initial cycle. However, these peaks disappeared after the initial cycle, indicating passivation of LiMn2O4thin-film electrode. X-ray photoelectron spectroscopy revealed that LiF was formed on the surface, and it should be the cause of the passivation. The influence of electrolyte, elevated temperature and additive on the passivation behavior will be discussed in the meeting. Acknowledgment This work was partially supported by CREST, JST. Figure 1

Interdigitated metal electrodes for high-resolution in situ electrochemical NMR

Despite being among the most widely used spectroscopic methods, high-resolution NMR has not yet been applied routinely to electrochemistry and (organic) electrosynthesis, due largely to the incompatibility between NMR detection and electrical conduction of electrochemistry. Here, we introduce a straightforward, easy-to-construct system that incorporates high-resolution (HR) in situ NMR spectroscopy with electrochemistry by using cylindrically symmetric interdigitated metal (Au) electrodes. The constructed system is simple to build, inexpensive, and robust. It requires with minimal setup time and can be used with conventional commercial probes without the need of any modifications to them. To demonstrate the feasibility and performance of the system, we used 1H NMR to monitor the reversible redox reaction of ferrocene and 13C NMR to follow the electro-oxidation reaction of methanol on a commercial ptru electrocatalyst.

Electrically Driven Motion of an Air Bubble on Hemispherical Oil/Water Interface by Three-Phase Boundary Reactions

Our electrochemical cell consisted of a ferrocene-included hemispherical nitrobenzene (NB) droplet on the glassy carbon (GC) electrode which was immersed in the aqueous solution including sodium sulfate and sodium dodecyl sulfate (SDS). When an air bubble was injected near the boundary between the oil and the aqueous phase, it stayed at the top of the hemisphere on the boundary so that the lower half of the bubble was put in oil and the other half was in water. From the force balance of surface tension and buoyancy of the bubble, the bubble took an energetic minimum at the interface. It sank into the oil phase when ferrocene in the oil was electrochemically oxidized through the GC electrode by the three-phase boundary reaction. The electrochemical reduction caused the bubble to move back toward the aqueous phase. The motion of the bubble was synchronized with the redox reaction of ferrocene. The potential step oxidation showed such a rapid response that the motion could not be attributed to diffusion of ferricenium ion from the three-phase boundary to the bubble. Our idea of explaining the rapidity was the translational motion of the SDS layer along the boundary, which was driven by the difference in the surface concentration of SDS caused by the electrochemical generation of the ferricenium ion. The motion of the SDS layer was demonstrated by the shrinkage of the oil layer spread on the water surface when SDS solution was dropped on the oil layer. The spreading velocity was close to the velocity of propagating the oxidation of ferrocene to the bubble.

The electrochemical redox reactions in silica sol–gel glass monoliths and films with embedded organic electrolyte

The electrochemical redox reaction of ferrocene and Co(II)tris(bipyridine) has been studied in silica sol–gel glass with embedded organic electrolyte. This material has been prepared by acid catalysed hydrolysis of the tetraalkylorthosilicate sol mixed with salt solution in organic polar solvent. Tetramethyl- or tetraethylorthosilicate was used as precursor. Lithium or tetraalkylammonium perchlorate solution in propylene carbonate or sulpholane was used as modifier. Sol–gel glass has been prepared in the form of a monolith or film. The electrochemical behaviour of the redox probe was studied by cyclic voltammetry and chronoamperometry on ultramicroelectrodes in the absence of macroscopic liquid phase. The accessible potential window in solid material is more narrow than in analogous liquid organic electrolyte. The shape of the cyclic voltammograms corresponding to the electrochemical redox reaction in sol–gel monolith is similar to that obtained in liquid electrolyte and does not depend on gel ageing. On the other hand, the current substantially decreases during the first few days after gelation, and later becomes weakly dependent on ageing. The precursor, salt, solvent and redox probe affect the motion rate of the redox probe. The latter is five times slower in electrolyte made of tetraethylorthosilicate in comparison to that obtained using the tetramethyl derivative. The diffusion coefficient of ferrocene is larger in the gel obtained in the presence of the large tetraalkylammonium cations. The electro-oxidation of ferrocene was also studied in films made from tetraethylorthosilicate, cast on the surface of the electrode assembly. The magnitude of the current is similar to that obtained in a glass monolith made of the same material.

Direct Observation of Perchlorate Incorporation Induced by Redox Reaction of Ferrocene Terminated Self-Assembled Monolayer Studied by in situ FT-Surface Enhanced Raman Spectroscopy

Abstract The incorporation of ClO4− into 8-ferrocenyloctanethiol (8FT) self-assembled monolayer (SAM) induced by the redox reaction at a gold wire electrode was demonstrated using in situ FT Raman spectroelectochemistry. Upon oxidation of the 8FT SAM, a band attributed to ClO4− was clearly observed and the band disappeared in its reduced state. On the other hand, when HNO3 was used as a supporting electrolyte, the band attributed to NO3− was not observed in the oxidized form of 8FT.

Electrochemical redox reaction in a silica sol-gel glass with embedded organic electrolyte

The electrochemical redox reaction of ferrocene was studied in silica sol-gel glass with embedded organic electrolyte. This material has been prepared by mixing hydrolysed tetramethylorthosilicate sol with propylene carbonate LiClO 4 solution containing ferrocene and further gelation in a form of block or film. The electrochemical behaviour of encapsulated ferrocene was studied by cyclic voltammetry, chronoamperometry, differential pulse voltammetry and impedance spectroscopy on ultramicroelectrodes. The shape of the cyclic voltammograms corresponding to the electrooxidation of ferrocene in sol-gel block is similar to that obtained in liquid electrolyte and it does not depend on gel aging. The current substantially decreases during the first few days after gelation. Later it becomes weakly dependent on aging and the apparent diffusion coefficient of ferrocene in the gel block is about half of that in liquid electrolyte. The electrooxidation of ferrocene also occurs in film of the analogous sol-gel material cast on the surface of the electrode assembly.

Mass transport accompanied with electron transfer between the gold electrode modified with 11-ferrocenylundecanethiol monolayer and redox species in solution — an electrochemical quartz crystal microbalance study

Abstract An electrochemical quartz crystal microbalance (EQCM) was employed to investigate mass transport during the redox reaction of the ferrocenylundecanethiolate (FcC 11 S(H)) monolayer modified gold electrode in solution containing other redox species. The FcC 11 S-monolayer on gold acts as a barrier for the electron transfer between a gold electrode and Fe(CN) 6 4−/3− in solution and as a mediator for the reduction of Fe 3+ in solution. In both cases, electrochemical current responses were complicated because the observed currents were due to the redox of both the ferrocenyl group immobilized on gold and others in electrolyte solutions. The frequency change, i.e. interfacial mass change on the gold electrode surface, was observed only during the redox of ferrocenyl groups. The complex current response was deconvoluted into the current components of the redox reaction of ferrocene and that of other redox species in solution by comparing cyclic voltammograms with the current calculated from frequency changes.

Application of SPE composite microelectrodes to the study of the spillover of adsorbed species on electrode surfaces

The electrochemical behavior of ferrocene in acetonitrile at the platinum|Nafion® interface was investigated using SPE composite microelectrodes. Two parallel reactions take place at the interface. The redox reaction of ferrocene|ferricinium ions predominates at the platinum|Nafion® composite microdisk electrode, while the adsorption or desorption of atomic hydrogen predominates at the platinum black|Nafion® composite powder microelectrode. This fact implies that the electrochemical reactions take place only at the interface and the adsorption of atomic hydrogen can occur on surface sites remote from the interface. The SPE composite microelectrode seems to be a potential technique of investigating the spillover of adsorbed species on the electrode surface.

Mass transport accompanied with electron transfer between the gold electrode modified with 11-ferrocenylundecanethiol monolayer and redox species in solution — an electrochemical quartz crystal microbalance study

An electrochemical quartz crystal microbalance (EQCM) was employed to investigate mass transport during the redox reaction of the ferrocenylundecanethiolate (FeC11S(H)) monolayer modified gold electrode in solution containing other redox species. The FeC11S monolayer on gold acts as a barrier for the electron transfer between a gold electrode and Fe(CN)64−/3− in solution and as a mediator for the reduction of Fe3+ in solution. In both cases, electrochemical current responses were complicated because the observed currents were due to the redox of both the ferrocenyl group immobilized on gold and others in electrolyte solutions. The frequency change, i.e. interfacial mass change on the gold electrode surface, was observed only during the redox of ferrocenyl groups. The complex current response was deconvoluted into the current components of redox reaction of ferrocene and that of other redox species in solution by comparing cyclic voltammograms with the current calculated from frequency changes.

Kinetics of glassy carbon electrodes coated with polystyrene films containing ferrocene and ionic surface-active agents

Glassy carbon electrodes coated with polystyrene films containing ferrocene show redox activity when a cationic surface-active agent, lauryltrimethylammonium chloride (LMA), or an anionic surface-active agent, sodium n-dodecylbenzenesulphonate (DBS), is added to the film. Chronoamperometry reveals that the redox reaction of ferrocene in the presence of DBS in the film is accompanied by the diffusion of electrolyte cations in the polymer layer and that ionized DBS works as a charge compensater of the resulting ferricinium cations. Similarly, when LMA is present in the film, electrolyte anions are involved in the redox reaction of the immobilized ferrocene. The rate of the electron-transfer reaction between the electrode substrate and the polymer layer, which is evaluated by normal pulse voltammetry, is influenced greatly by the kind and the amount of ionic surface-active agents in the polystyrene film.

Synthesis of ferrocenyl derivatives of anthracene

1-Ferrocenylantraquinone has been synthesized from the cheap and commercially available 1-diazoniumanthraquinone (Aldrich Fast Red Al salt). Reduction of this anthraquinone with aluminium alkoxide has given good yields of 1-ferrocenylanthracene, the first preparation of such polycyclic ferrocenes. The TCNE adduct of the anthracene was prepared in good yield, in marked contrast to the outcome of the redox reaction of ferrocene itself with TCNE. No oxidation was observed with TCNQ. Diels-Alder addition of benzyne resulted in a very low yield (∼ 1%) of 1-ferrocenyltriptycene. The 1H and 13C NMR spectra are reported, and discussed in detail together with 57Fe Mössbauer data.

Electrocatalytic oxidation of ascorbic acid and voltammetric determination with a ferrocene-modified platinum electrode

Ferrocene attached to the surface of a platinum electrode catalyses the electrochemical oxidation of ascorbic acid in acidic buffer solutions. The overpotential for ascorbic acid oxidation is decreased by 150 mV at pH 2.2 compared with reaction at bare platinum; and an increase in anodic current and decrease in cathodic current for the redox reaction of ferrocene occurs on addition of ascorbic acid to the solution. The ferrocene-modified electrode is useful for the voltammetric determination of ascorbic acid in natural fruit juices. The advantages result from the electrocatalytic effect and from the prevention of adsorption of inhibitory substances from solution.