Potential Step Method Research Articles

(Invited) Investigation of Anion Role during Electrochemical CO2 Reduction on Copper Sulfide (CuS) by Potential-Step Method

One of the candidate materials as CO2 reduction electrocatalysts is metal sulfide, generally because it possesses multiple adsorption sites to overcome scaling relationship. Furthermore, metal sulfide has unique redox property that not only metal sites but anion (sulfur) sites are redox active. To use this property efficiently, this work focused on potential-step method, in which two different electrode potential are applied to an electrode during CO2 reduction process. Previous electrochemical CO2 reduction works using metal copper (K. Kimura et al., ACS Catal., 10, 8632-8639, 2020) and tin sulfide (A. Woldu et al., Angew. Chem. Int. Ed., 62, 2023) electrodes as catalysts clearly demonstrated the usefulness of this method for CO2 reduction, however, its effect on anion behavior and CO2 reduction intermediate is under exploration. In this work, using copper sulfide (CuS) as a model compound, anion role on CO2 reduction reaction by potential-step method on metal sulfide was investigated. CuS was synthesized with solvothermal method using Cu(NO3)2, thioacetamide, and ethylene glycol as precursor solution. X-ray diffraction (XRD) and Raman measurements revealed that the obtained CuS possesses hexagonal structure. To prepare working electrode, dispersion solution of CuS in water and ethanol containing Sustainion as a binder was dropped onto carbon paper electrode. Electrochemical CO2 reduction properties were examined using H-type cell and 0.1 M KHCO3 aq. as an electrolyte. Platinum mesh and Ag/AgCl (sat. KCl) were used as counter and reference electrodes, respectively. By applying potential step method, selectivity for formic acid (HCOOH) was increased compared with conventional constant-potential method. XRD and X-ray photoelectron spectroscopy measurement revealed that Cu redox state was changed between Cu0 and Cu+ states during cathodic and anodic potential application, respectively. Furthermore, combining in situ Fourie Transformation Infrared spectroscopy and controlling experiment using Cu0 electrode, Cu2O, and Cu0 in the presence of S2- ion, this work proposed possible intermediate species and how they were affected by anions involved in the reaction to generate specific products. Namely, surface-adsorbed sulfur enhanced the adsorption of H+ ion and contributed to promoting all the reaction, while bulk sulfur stabilized CO intermediate to increase HCOOH selectivity. In addition, existence of oxygen generated Cu+ sites and resulting Cu+/Cu0 interface contributed to producing multi-carbon compounds. Our results indicated that the regulation of anion behavior by potential-step method is one of the promising strategies to control product selectivity of electrochemical CO2 reduction.

Intense annihilation electrogenerated chemiluminescence from tris(2-phenylpyridinato)iridium(III) with organic radical cations and anions

The electrogenerated chemiluminescence (ECL) of 0.2 mM tris(2-phenylpyridinato)iridium(III) (Ir(ppy)3) in acetonitrile with a potential step method was dramatically enhanced by the electrochemically generated radical cation of 10-methylphenothiazine (MePT), thianthrene (TH), and dibenzo-1,4-dioxin (DD) or the radical anion of benzophenone (BP) and benzonitrile (BN). In the case of using the radical cation of phenothiazine (PT), no ECL was seen. Among the binary systems containing 0.2 mM Ir(ppy)3 and 10 mM parent molecule of the radical ions, intense annihilation ECL of Ir(ppy)3 was observed from a solution containing BN; the ECL intensity was about 250 times greater than that of the single system of 0.2 mM Ir(ppy)3. Among the cases using the radical cations, the ECL intensity with TH was the largest (about 90 times higher than that of the single system). The mechanism for enhancing the ECL is discussed based on the redox potential, energy level of the lowest triplet excited (T1) state, and electron-donating and −accepting characteristics. The electron transfer reaction between the reduced form of Ir(ppy)3 (Ir(ppy)3•−) and the radical cations can produce the T1 state of Ir(ppy)3 (3Ir(ppy)3*) and that of MePT, TH, and DD, whereas the electron transfer reaction between the oxidized form of Ir(ppy)3 (Ir(ppy)3•+) and the radical anions can produce 3Ir(ppy)3* but not the T1 state of BN or BP. The lower ECL intensity using the radical cations relative to that of using BN suggests that the triplet energy transfer from the parent molecule of the radical cations to Ir(ppy)3 is not efficient. It is also shown that the homogeneous electron transfer reaction between Ir(ppy)3 and the electrochemically generated radical cation of TH and radical anion of BN to produce Ir(ppy)3•+ and Ir(ppy)3•−, respectively, which facilitates an ion annihilation reaction between Ir(ppy)3•− and Ir(ppy)3•+, is also responsible for the intense ECL.

Influence of a polymeric gel on the in situ electropolymerization of 3,4-ethylenedioxythiophene and application in irreversible electrochemical indicators

Electropolymerization triggered inside of a pre-assembled device can produce a high-contrast, visually irreversible color change. This format of electrochemical indicator has potential applications in a broad range of commercial sectors, including authenticity labeling, healthcare, food packaging, and logistics. However, there is limited work exploring how polymer gel electrolytes, which are commonly employed in flexible electrochemical devices, influence the electropolymerization process. Here, we study the electrochemical polymerization of 3–4-ethylenedioxythiphene (EDOT) in a UV-curable ethylene oxide-propylene oxide-allyl glycidyl ether (EO-PO-AGE) polymer gel electrolyte. Using potential step methods and cyclic voltammetry, we find that the addition of the polymer gel matrix lowers the overpotential required for film formation by 0.1 V compared to the liquid electrolyte. Furthermore, indicators with the polymer gel electrolyte show an increase in coloration efficiency, and greater visual homogeneity compared to indicators with the liquid electrolyte.Graphical

Electrochemical Impedance Spectroscopic Investigations of Nanocomposite Thin-Film Formation at an Electrified Micro Liquid-Liquid Interface

Herein, the interface between two immiscible electrolyte solutions (ITIES) has been exploited as a pristine platform for electropolymerization of the 2D and 3D nanocomposite materials, i.e., metal nanoparticles (NPs) embedded within a conductive polymer matrix that are electrogenerated/electropolymerized simultaneously The free-standing conductive thin film can be prepared with an adjustable loading of metallic NPs, to be tailored for a variety of applications, including as catalytic electrodes in fuel cells, or act as a bioreceptor in a biosensor. Electrochemical impedance spectroscopy (EIS) has been used to investigate mechanistic aspects of film growth through two types of charge transfer processes, ion and electron transfer, that occur during electropolymerization. The thermodynamics of a heterogeneous electron transfer (HET) between redox centers, KAuCl4(aq) and terthiophene (TT, org), across the interface governs the electropolymerization reaction, including the rate, which is itself affected by the rate of diffusion of reactants toward the interface, ohmic resistance of the two electrolyte solutions, distance between reactants due to arrangement of ions at the interface, and reorganization energy of the involved species in the reaction. Electropolymerization is controlled through application of an applied external potential difference and monitored voltammetrically as well as by EIS. Curve fitting of EIS data was performed using an equivalent circuit incorporating a phase constant element (CPE) parallel to a resistor for non-ideal interfacial capacitance, and HET resistance across the film as it forms at the ITIES. Next, those elements are parallel to a resistor (R), and a Warburg element (W) to approximate ion transfer across the ITIES/porous thin-film as it grows (Fig. 1). Data suggest that the films electronic conductivity improves with increasing the [TT]:[KAuCl4] ratio. Increased capacitance was hypothesized to be linked to an increase in the effective surface area of the polymer film during its growth phase versus the molecularly smooth ITIES. Higher [TT]:[KAuCl4] ratios elicited higher capacitance as well as diffusion resistance which can be attributed to formation of a more compact film structure. Cyclic voltammetric and potential step methods are compared and discussed, highlighting the formed films final properties, including film thickness and conductivity. Figure 1

Green electrochemical method for the synthesis of nitro and azo derivatives based on mefenamic acid

Electrochemical study of mefenamic acid (MFA) was carried out with details in water/ethanol mixture by the various voltammetric techniques. The results showed that the oxidation of MFA is highly dependent on pH and follows the Eir mechanism. The EpA1-pH diagram plotted based on the differential pulse voltammograms shows two linear segments, 66 and 26 mV/pH slope. Also, the diffusion coefficient and the surface excess, Ӷ* of MFA in aqueous buffered solution, determined by using the single potential-step chronoamperometry and chronocoulometry methods. Electrochemical nitration of MFA in an aqueous solution and the presence of nitrite ion (1) were both investigated by the cyclic voltammetry and controlled-potential coulometry techniques. Our results indicate that the oxidized form of MFA participates in a Michael-type addition reaction with nitrite ion (1) to form the corresponding Nitromefenamic acids (MFA-4-NO2 and MFA-5-NO2). Also, in another part, a computational study based on the density functional theory (DFT/B3LYP) was performed for the prediction of the best possible pathway in the nucleophilic addition of nitrite ion (1). The electrochemical reduction of produced nitromefenamic acids was investigated using cyclic voltammetry and controlled-potential coulometry techniques. Eventually, two new azo derivatives have been generated via electroreduction of produced nitromefenamic acids and conduction of diazotization reaction, respectively. Both nitro and azo products are approved as paints.

Synthesis of new azobenzo[c]cinnolines and investigation of electronic spectra and spectroelectrochemical behaviours

A series of disazobenzo[c]cinnoline dyes was prepared by coupling reaction of 3,8-dihydroxybenzo[c]cinnoline with diazotised aromatic amines. The structures of these dyes were confirmed using UV–Vis, FTIR, 1H NMR, LC-MS/MS and LC-MS/TOF spectroscopic techniques. 13C NMR, 13C-DEPT, 1H–1H COSY, 1H–13C HMQC and 1H–13C HMBC spectra of dye 12 were demonstrated in this study. In addition, the effects of the substituent attached to the phenyl ring, solvent and acid-base on the UV-Vis spectra of the dyes were investigated. Besides, voltammetric and spectroelectrochemical behaviours of four disazobenzo[c]cinnolines (2, 8, 11 and 13) in acetonitrile (ACN) solution were also evaluated. It was observed that the disazobenzo[c]cinnoline derivatives indicated reversible voltammetric behaviour in acetonitrile-tetrabutylammonium perchlorate (ACN-TBAP) solution. A square-wave potential step method coupled with optical spectroscopy was used to probe switching times and optic contrast of the dyes.

Electrochemical Detection of 4-Nitrophenol on a Nanoporous Gold Electrode Prepared by One-Step Anode Potential Step Method

The wastewater containing nitrophenol compounds is discharged into the water and soil environment, causing severe environmental pollution problems. In this paper, a one-step anodic potential step method involving Au(I) disproportionation was used to prepare nanoporous gold (D-NPG) electrodes for the electrochemical detection of 4-nitrophenol (4-NP) by differential pulse voltammetry (DPV). The D-NPG electrode has a high current response to the oxidation peak of 4-hydroxylaminophenol, a product of 4-NP electroreduction. This peak is used in the 4-NP detection. Under the optimized conditions, the resulting detection range is wide (0.01~20 µM) and the detection limit is low (3.5 nM), and its anti-interference ability is good. It can be used for the electrochemical detection of 4-NP in real water samples.

Electrochemical measurements of the corrosion of pure Fe and JLF-1 steel in HF-containing molten FLiNaK salt

In order to establish a liquid blanket using a Li-containing molten fluoride salt, the corrosion rate and mechanism of pure Fe and JLF-1 steel in FLiNaK (LiF-NaF- KF = 46.5-11.5-42.0) was investigated by one of the electrochemical methods, the potential step method. Simulating the TF breeding in the blanket, HF gas was injected into FLiNaK at 773 K. The partial pressure of HF gas (pHF) was varied from 8.59 to 2.46 × 103 Pa. The current-potential curves of pure Fe and JLF-1 steel were measured in an electrochemical cell and fit by the Butler-Volmer equation with limited current density. The corrosion current density (icor) of pure Fe increased with pHF as icor=0.6pHF. The corrosion rates of pure Fe and JLF-1 steel were close. In order to keep the uniform corrosion rate of JLF-1 steel below 0.1 mm/year in the blanket, HF concentration in FLiNaK is required less than 1.2 × 10−4 molHF/m3. The cathodic current density (iLc) was proportional to pHF as iLc=-0.11pHF, and, therefore, the rate-limiting process of HF corrosion of pure Fe is predicted to be HF or H+ diffusion in FLiNaK.

Effect of sulfate adlayer on formic acid oxidation on Pd(111) electrode

The kinetics of formic acid oxidation (FAO) on Pd(111) in 0.1 mol/L H2SO4+0.1 mol/L HCOOH with and without addition of Na2SO4 is studied using cyclic voltammetry and potential step method, which is compared with that in 0.1 mol/L HClO4. It is found that adsorbed sulfate has significant inhibition effect on FAO kinetics. After addition of 0.05 mol/L or 0.1 mol/L Na2SO4, FAO current in the negative-going scan is found to be significantly smaller than that at the same potential in the positive-going scan. We speculate that at potentials positive of the phase transition potential for the (SO4ad*)m+[(H2O)n−H3O+] or (SO4ad*)m+[Na+(H2O)n−H3O+] adlayer, the adlayer structure probably becomes denser and more stable with the increase of potential or with the addition of Na2SO4. The formation of connected adlayer network greatly enhance the stability of the adlayer, and the insertion of positive-charged H+ or Na+ into the adlayer network further reduces the electrostatic repulsion between partially charged sulfates. As a result, the destruction/desorption of compact sulfate adlayer becomes more difficult, which leaves much less free sites on the surface for FAO, and thus FAO kinetics at higher potentials and in the subsequent negative-going potential scan is significantly inhibited.

Investigations on kinetics properties of hydrogen adsorbing/desorbing reactions for metal hydride electrodes

As we know, the kinetics properties of hydrogen adsorbing/desorbing reactions for metal hydride electrodes are determined by the rates of the charge transfer, hydrogen transfer and hydrogen diffusion reactions. In previous studies, not only the hydrogen transfer process was always ignored, but also the values of the kinetics parameters for the charge transfer and hydrogen diffusion processes were quite different. Therefore, the purpose of this work is to investigate the key issues of the kinetics properties for hydrogen adsorbing/desorbing reactions. Firstly, the hydrogen transfer process was thoroughly studied by electrochemical impedance spectrum (EIS) method, in which it emphasized the corresponding relationship between the electrode process of hydrogen adsorbing/desorbing reactions and the time constants presented in different frequency regions of impedance spectrum. The values of the hydrogen transfer resistance were calculated as a function of depth of discharge (DOD). Meanwhile, almost all the electrochemical techniques including linear polarization curves (LP), constant potential step method (CPSM), galvanostatic intermittent titration technique (GITT), cyclic voltammetry method (CV) and EIS were used to measure the kinetics parameters for the charge transfer and hydrogen diffusion processes. Moreover, the factors causing the discrepancy of the kinetics parameters were analyzed in detail.

Hydrogen storage in a rare-earth perovskite-type oxide La0.6Sr0.4Co0.2Fe0.8O3 for battery applications

Recently, rare-earth perovskite-type oxides with the general formula ABO3 (A rare earth element, B transition metal, O oxygen) are regarded as promising materials for Ni/oxide batteries due to their hydrogen storage ability. In the present study, the hydrogen storage properties of the rare-earth perovskite-type oxide La0.6Sr0.4Co0.2Fe0.8O3 were evaluated in alkaline solution and at various temperatures. The hydrogen storage properties were investigated electrochemically by applying galvanostatic charge/discharge currents. Electrochemical pressure–composition–temperature isotherms were constructed using the Nernst equation. The exchange current density and proton hydrogen diffusion coefficient were calculated using linear polarization measurements and the potential-step method, respectively. Interestingly, the maximum hydrogen absorption capacity, re-calculated from the electrochemical capacity, is 1.72 wt% at 333 K and 6 mol·L−1 KOH. In addition, the hysteresis value, calculated from pressure–composition–temperature isotherms, was 429 J·mol−1 at 333 K, while the self-discharge rate was about 25% after 24-h storage at open circuit and at 333 K.

Dynamics of oxide growth on Pt nanoparticles electrodes in the presence of competing halides by operando energy dispersive X-Ray absorption spectroscopy

In this work we studied the kinetics of oxide formation and reduction on Pt nanoparticles in HClO4 in the absence and in the presence of Br− and Cl− ions. The study combines potential step methods (i.e. chronoamperometry and choronocoulometry) with energy dispersive X-ray absorption spectroscopy (ED-XAS), which in principle allows to record a complete XAS spectrum in the timescale of milliseconds. Here, the information on the charge state and on the atomic surrounding of the considered element provided by XAS was exploited to monitor the degree of occupancy of 5d states of Pt in the course of oxide formation and growth, and to elucidate the competing halide adsorption/desorption phenomena. Electrochemical methods and XAS agree on the validity of a log(t) depending growth of Pt oxide, that is significantly delayed in the presence of Cl− and Br− anions. In the proximity of formation of one monolayer, the growth is further slowed down.

Visible-light-inducible voltage current property of hydrogel on laminated hydrogenated amorphous silicon film

To investigate the possibility of photoinduced controllability of an electrochemical element, using agarose gel, amino acids, and a hydrogenated amorphous silicon (a-Si:H) thin film, an electrochemical element, which constituted the fluorine doped tin oxide glass (FTO/glass) transparent conductive positive electrode, 2 mm thick 0.05 M-Asp gel, 2 mm thick 0.05 M-Arg gel, a-Si:H film (hydrogen 0–40%, thickness 16.2 nm), a-Si:H film (hydrogen 20%, thickness 81 nm), and FTO/glass transparent conductive negative electrode, was constructed. The visible-light-induced current vs a potential behavior was measured by potential step method. Compared with the case of hydrogen concentration of , in the case of current vs potential increased. On the other hand, in the case of , current became smaller than that in the . From these results, a new application aspect of a-Si:H for the control of ion conductivity in organic molecules was revealed.

A comprehensive study on electrochemical oxidation of 2-acetamidophenol (ortho-acetaminophen). A green galvanostatic method for the synthesis of di-arylsulfonyl-2-acetamidophenol derivatives

Electrochemical oxidation of 2-acetamidophenol (ortho-acetaminophen) in water/ethanol (50/50, v/v) mixture, with different pH values was studied by potential sweep methods (CV and LSV), potential step methods (chronoamperometry and chronocoulometry) and controlled-potential coulometry. The cyclic voltammograms of 2-acetamidophenol show a well-defined anodic peak with different potentials, over the studied pH range (1-13). The Pourbaix diagram for 2-acetamidophenol comprises three linear segments which indicates the occurrence of different anodic reactions. In addition, the results indicate that electrochemically generated ortho-benzoquinoneimine can be successfully employed as a Michael acceptor in addition reactions with arylsulfinic acids to produce the corresponding bis(arylsulfonyl) acetamidophenols. In this work, some new bis(arylsulfonyl)acetamidophenol derivatives in water/ethanol (50/50, v/v) mixture, with high yields, under green conditions using an environmentally friendly galvanostatic method, are provided.

Thermal, Physical, and Electrochemical Properties of Li[N(SO2F)2]-[1-Ethyl-3-methylimidazolium][N(SO2F)2] Ionic Liquid Electrolytes for Li Secondary Batteries Operated at Room and Intermediate Temperatures

The Li[FSA]-[C2C1im][FSA] (FSA–: bis(fluorosulfonyl)amide and C2C1im+: 1-ethyl-3-methylimidazolium) ionic liquids have been studied as electrolytes for Li secondary batteries, though their thermal, physical, and electrochemical properties have not been systematically characterized. In this study, the thermal and transport properties of Li[FSA]-[C2C1im][FSA] ionic liquids as a function of the Li[FSA] molar fraction and temperature, in view of their operation at both room and intermediate temperatures. Differential scanning calorimetric analysis revealed that this system has a wide liquid-phase temperature range from Li[FSA] fractions of 0.0 to 0.4 and indicated the existence of the Li[C2C1im][FSA]2 line compound. Single-crystal X-ray diffraction analysis was used to determine the crystal structure of Li[C2C1im][FSA]2, which consists of Li+ octahedrally coordinated by six O atoms originating from four FSA– anions. The temperature dependences of the viscosity and ionic conductivity were fitted by the Vogel–Tammann–Fulcher equation, and the viscosity and molar ionic conductivity were connected by the fractional Walden rule. Lithium–metal deposition/dissolution efficiency decreased with increasing measurement temperature and decreasing Li[FSA] fraction. Aluminum corrosion at positive potentials was investigated by a potential step method, which revealed that the stability of an aluminum electrode was improved at high Li[FSA] fractions at 298 K, and the corrosion-limit potential decreased at elevated temperatures.

The effect of carbon within corrosion pits of iron in chloride solutions

ABSTRACTIron artificial pits have been used in this work to investigate the effect of a carbon-based black layer that can form within a pit during iron dissolution in HCl solutions. Commercial purity iron (99.5%) and high purity iron (99.99+%) have been compared, and a black layer has been observed only in the 99.5% iron pit. It has been found that the formation of a black layer within an iron artificial pit is potential dependent: it can form at applied voltages below 0.2 V(SCE), but not at 0.6 V(SCE). The presence of a black layer can decrease the rate of mass transport inside a pit, which may help to maintain the aggressive acidic solution in an active pit. This effect has been characterised quantitatively via potentiostatic and potential step methods. In addition, the black layer has also been found to induce a small extra resistance in the solution.

A highly sensitive metronidazole sensor based on a Pt nanospheres/polyfurfural film modified electrode

A sensitively electrochemical metronidazole sensor basing on a Pt nanospheres/polyfurfural modified glassy carbon electrode.

Electrodeposited Ni(OH)2 nanostructures on electro-etched carbon fiber paper for highly stable supercapacitors

Herein, we introduce a facile, inexpensive and fast, and additive-/template-free method to fabricate highly stable nickel hydroxide nanofibers for supercapacitor applications. Ni(OH)2 nanofibers were electrodeposited on electro-etched carbon fiber paper by a potential step method (Ni(OH)2-ECFs) and characterized using scanning electron microscopy and X-ray diffraction analysis. Electrochemical performance of Ni(OH)2-ECF was studied in symmetric two-electrode assembly by cyclic voltammetry, galvanostatic charge–discharge method, and electrochemical impedance spectroscopy. A specific capacitance of 277.5 F g−1 was achieved for the symmetric supercapacitor based on two identical Ni(OH)2-ECFs. Our findings demonstrate high-rate capability with excellent stability (approximately 100 % capacitance retention) for Ni(OH)2-ECF supercapacitor, originated from the intimate contact between Ni(OH)2 and ECF. Our studies suggest the Ni(OH)2-ECF electrode as an excellent material for supercapacitor applications.

Electrode Reactions Coupled with Chemical Reactions of Oxygen, Water and Acetaldehyde in an Ionic Liquid: New Approaches for Sensing Volatile Organic Compounds

Water and oxygen are ubiquitous present in ambient conditions. This work studies the unique oxygen, trace water and a volatile organic compound (VOC) acetaldehyde redox chemistry in a hydrophobic and aprotic ionic liquid (IL), 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide ([Bmpy][NTf2]) by cyclic voltammetry and potential step methods. One electron oxygen reduction leads to superoxide radical formation in the IL. Trace water in the IL acts as a protic species that reacts with the superoxide radical. Acetaldehyde is a stronger protic species than water for reacting with the superoxide radical. The presence of trace water in the IL was also demonstrated to facilitate the electro-oxidation of acetaldehyde, with similar mechanism to that in the aqueous solutions. A multiple-step coupling reaction mechanism between water, superoxide radical and acetaldehyde has been described. The unique characteristics of redox chemistry of acetaldehyde in [Bmpy][NTf2] in the presence of oxygen and trace water can be controlled by electrochemical potentials. By controlling the electrode potential windows, several methods including cyclic voltammetry, potential step methods (single-potential, double-potential and triple-potential step methods) were established for the quantification of acetaldehyde. Instead of treating water and oxygen as frustrating interferents to ILs, we found that oxygen and trace water chemistry in [Bmpy][NTf2] can be utilized to develop innovative electrochemical methods for electroanalysis of acetaldehyde.

Hydrogen Diffusion and Trapping in Fluoride Salt Melts and Graphite Electrodes

This paper presents an approach currently under development at University of Wisconsin Madison to study tritium transport in high temperature fluoride salt systems and absorption in graphite. This work has applicability to tritium management in Fluoride Salt Cooled High Temperature Nuclear Reactors (FHRs). The applicability of the Double Potential Step Method (DSPM) and Electrochemical Impendence Spectroscopy (EIS) originally developed for the study of hydrogen transport in metals from water solutions is discussed for the salt-graphite system. Mechanistic models for hydrogen transport and trapping in graphite are reviewed. The experimental setup and electrochemical cell used with 2LiF-BeF2 (flibe) salt at 500-700°C is described. The design and preliminary characterization data for a Ni/Ni(II) flibe thermodynamic reference electrode are presented.