Oxidation Of Ferrocyanide Research Articles

On the impedance response of reactions influenced by mass transfer

A direct relationship is derived between the charge-transfer resistance and the resistive terms ascribable to diffusion for a faradaic reaction influenced by transport of the reacting species to the electrode. The charge-transfer resistance is shown to approach a finite value for potentials at which the current is limited by mass transfer and, conversely, the diffusion impedance approaches a finite value when the current is controlled by kinetics. Supporting experimental results are presented for both an irreversible (oxygen reduction reaction) and a quasi-reversible (ferrocyanide oxidation) electrochemical systems investigated with a rotating- disk electrode.

Kinetic and Diffusion-Driven Instabilities in the Bromate–Sulfite–Ferrocyanide System

The spatiotemporal dynamics of the bromate-sulfite-ferrocyanide (BSF) reaction-diffusion system in a open one-side-fed reactor (OSFR) is investigated by numerical simulations. The results of the simulations are compared with experiments performed in an annular shape OSFR. Both kinetic and diffusion-driven instabilities are identified in the model. There are two hydrogen ion consuming pathways in the mechanism: the partial oxidation of sulfite to dithionate and the oxidation of ferrocyanide by bromate ions. Their dynamical effects are similar, as they support the same negative feedback loop via sulfite ion. However, the time scale of the oxidation of ferrocyanide by bromate ions can be conveniently controlled by the input feed concentrations, thus it provides a more flexible way to find spatiotemporal oscillations. Long-range activation due to the relative fast diffusion of hydrogen ions compared to the other reactants can also result in oscillations in this mechanism. We show that the spatial extent of the reaction-diffusion medium along the direction of the diffusive feed (the thickness) acts as a general control parameter of the dynamics. Oscillations, either originated in kinetic or in diffusive instabilities, can only develop in a narrow range of the thickness. This property explains the experimentally often observed spatial localization of the oscillations. A reciprocal relationship is found between two main control parameters of the dynamics, which are the thickness and the hydrogen ion input feed concentration.

Electrocatalytic water treatment using carbon nanotube filters modified with metal oxides.

This study examined the electrocatalytic activity of multi-walled carbon nanotube (CNT) filters for remediation of aqueous phenol in a sodium sulfate electrolyte. CNT filters were loaded with antimony-doped tin oxide (Sb-SnO2; SS) and bismuth- and antimony-codoped tin oxide (Bi-Sb-SnO2; BSS) via electrosorption at 2V for 1h and then assembled into a flow-through batch reactor as anode-cathode couples with perforated titanium foils. The as-synthesized pristine CNT filters were composed of 50-60-nm-thick tubular carbons with smooth surfaces, whereas the tubes composing the SS-CNT and BSS-CNT filters were slightly thicker and bumpy, because they were coated with SS and BSS particles ~50nm in size. Electrochemical characterization of the samples indicated a positive shift in the onset potential and a decrease in the current magnitude in the modified CNT filters due to passivation and oxidation inhibition of the bare CNT filters. These filters exhibited a similar adsorption capacity for phenol (5-8%), whereas loadings of SS and BSS enhanced the degradation rate of phenol by ~1.5 and 2.1 times, respectively. In particular, the total organic carbon removal performance and mineralization efficiency of the BSS-CNT filters were approximately twice those of the bare CNT filters. The BSS-CNT filters also exhibited an enhanced oxidation of ferrocyanide [FeII(CN)64-], which was not adsorbed onto the CNT filters. The enhanced electrocatalytic performance of the modified CNT filters was attributed to an effective generation of OH radicals. The surfaces of the filters were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy.

Simple and Ultrasensitive Chemically Amplified Electrochemical Detection of Ferrocenemethanol on 4-Nitrophenyl Grafted Glassy Carbon Electrode

Chemically amplified electrochemical detection, redox-active probe being amplified its electrochemical anodic current by a sacrificial electron donor presenting in solution, holds great potential for simple and quantitative bioanalytical analysis. Herein, we report the chemically amplified electrochemical analysis that drastically enhanced a detection of ferrocenemethanol (analyte) by ferrocyanide (chemical amplifier) on 4-nitrophenyl grafted glassy carbon electrodes at 60°C. The glassy carbon electrode grafted with a 4-nitrophenyl group using an electrochemical reduction suppressed the oxidation of ferrocyanide and thus enabled detection of ferrocenemethanol with excellent selectivity. The ferrocenemethanol was detected down to an nM range using a linear sweep voltammetry under kinetically optimized conditions. The detection limit was improved by decreasing the concentration of the ferrocyanide and increasing temperature. Keywords: Chemically amplified electrochemical detection, Ferrocenemethanol, Ferrocyanide, Nanomolar electrochemical detection, 4-nitrophenyl grafted glassy carbon electrode

Determination of Melamine by a Reduced Graphene Oxide–Gold Nanoparticle Composite Carbon Paste Electrode

ABSTRACTA reduced graphene oxide–gold nanoparticle composite was synthesized and characterized by the X-ray diffraction and microscopy. Modified carbon paste electrode was fabricated from the film of the composite. Adsorption of melamine on the composite material was characterized by scanning electrochemical microscopy. Melamine was determined by probing the decrease in the oxidation of ferrocyanide on the modified carbon paste electrode. An analytical method for the determination of melamine has been proposed using the modified electrode. The detection limit of the method was 2.23 µM.

Core-Shell Si-Ta3N5 Heterostructures As Photoanodes for Photoelectrochemical Water Splitting

Tantalum nitride (Ta3N5­) is a promising photoanode material for photoelectrochemical water splitting due to its n-type doping, bandgap of 2.1 eV, and band positions that straddle the redox potentials of both the hydrogen and oxygen evolution reactions.1 However, there are other challenges associated with Ta3N5 including poor charge transport properties, late photocurrent onset and photodegradation. To address all of these challenges, we fabricated efficient and stable core-shell heterostructured Si-Ta3N5 nanowire photoanodes coated with CoTiOx and NiO oxygen evolution co-catalysts. For metal oxide semiconductors with charge transport limitations such as short charge carrier diffusion lengths and/or lifetimes, previous device architecture strategies have included nanostructuring the oxide or coating it onto a conductive, high-aspect ratio scaffold.2, 3 In this work, a similar approach was applied to Ta3N5 to make a nanostructured core-shell Si-Ta3N5 device where the Si is a conductive, nanowire scaffold and the Ta3N5 is coated onto Si as a thin shell through which charge extraction should be efficient. Furthermore, if n-type Si is used, then a heterojunction between Si and Ta3N5 is formed enabling a tandem, dual-absorber configuration. This results in a 200 mV cathodic shift for photocurrent onset due to the photovoltage gained from Si and therefore improves the overall performance of the Si-Ta3N5 photoanode. The Si nanostructures were fabricated by a pseudo-Bosch deep reactive ion etching process,4 then tantalum oxide was coated onto Si by atomic layer deposition (ALD), and finally the tantalum oxide was nitrided in pure ammonia gas at 900 °C to yield crystalline Ta3N5. To gain a deeper understanding of charge transport within the thin Ta3N5 shells and to optimize the electrode performance, we varied the thickness of the shell between 10 and 70 nm and tested for photoelectrochemical ferrocyanide oxidation in a reversible ferri/ferrocyanide redox couple. We found that in a core-shell Si-Ta3N5 nanowire device, where light absorption should not vary as a function Ta3N5 thickness, photocurrent decreased with increasing Ta3N5 thickness, which indicates that charge extraction becomes problematic with thicker Ta3N5 films. As a clearer demonstration of this charge transport issue, we performed absorbed photon to current efficiency (A.P.C.E.) measurements using 10-70 nm films of Ta3N5 on planar Si and quartz substrates. Again, we found that A.P.C.E. decreased once the films were thicker than 30 nm, demonstrating that the minority carrier diffusion length is likely tens of nanometers. Finally, to address the problem of Ta3N5 photodegradation and to demonstrate photoelectrochemical performance for water oxidation with the core-shell system, CoTiOx and NiO catalysts were coated onto Si-Ta3N5. We found that CoTiOx, deposited by dipcoating from a sol-gel,5 pairs well with Ta3N5 as a cocatalyst and yields a photocurrent density of 2.6 mA/cm2 at 1.23 V vs. RHE. However, the device is not stable. With NiO deposited by ALD,6 we were able to achieve a photocurrent density of 2.4 mA/cm2 after Fe incorporation into NiO. A bare Si-Ta3N5 yields 0.7 mA/cm2. Furthermore, the Si-Ta3N5 coated with only ~1 nm of Ni(Fe)O loses 40-50% of its peak photocurrent over a 24 hour chronoamperometry test. Compared to the current Ta3N5 reports in the literature, the Ni(Fe)O catalyst affords noteworthy stability.7, 8 Therefore, in this work, we demonstrate a heterostructured Ta3N5 system with a core-shell Si-Ta3N5 dual absorber configuration that enabled earlier onset of photocurrent, efficient charge extraction from Ta3N5 and relatively stable long term water oxidation with a Ni(Fe)O co-catalyst.

Electrochemical Detection of Single Phospholipid Vesicle Collisions at a Pt Ultramicroelectrode.

We report the collision behavior of single unilamellar vesicles, composed of a bilayer lipid membrane (BLM), on a platinum (Pt) ultramicroelectrode (UME) by two electrochemical detection methods. In the first method, the blocking of a solution redox reaction, induced by the single vesicle adsorption on the Pt UME, can be observed in the amperometric i-t response as current steps during the electrochemical oxidation of ferrocyanide. In the second technique, the ferrocyanide redox probe is directly encapsulated inside vesicles and can be oxidized during the vesicle collision on the UME if the potential is poised positive enough for ferrocyanide oxidation to occur. In the amperometric i-t response for the latter experiment, a current spike is observed. Here, we report the vesicle blocking (VB) method as a relevant technique for determining the vesicle solution concentration from the collisional frequency and also for observing the vesicle adhesion on the Pt surface. In addition, vesicle reactor (VR) experiments show clear evidence that the lipid bilayer membrane does not collapse or break open at the Pt UME during the vesicle collision. Because the bilayer is too thick for electron tunneling to occur readily, an appropriate concentration of a surfactant, such as Triton X-100 (TX100), was added in the VR solution to induce loosening of the bilayer (transfection conditions), allowing the electrode to oxidize the contents of the vesicle. With this technique, the TX100 effect on the vesicle lipid bilayer permeability can be evaluated through the current spike charge and frequency corresponding to redox vesicle collisions.

Interrogation of immunoassay platforms by SERS and SECM after enzyme-catalyzed deposition of silver nanoparticles

The manuscript demonstrates the interrogation of immunoassay platforms after enzyme-catalyzed deposition of silver nanoparticles (AgNPs) using scanning electrochemical microscopy (SECM) and surface-enhanced Raman scattering (SERS). We have selected an immunoassay model platform for the determination of residues of the antibiotic sulfapyridine in milk. The assay involves a direct competitive approach with an HRP-labeled antigen analog and selective capture antibodies immobilized on the surface of glassy carbon plates modified with protein G. Interrogation of the modified substrate by SECM and SERS was carried out after enzyme-catalyzed in-situ deposition of AgNPs. The enhanced Raman scattering for proflavine in the presence of AgNPs was used as signalling system. Hexacyanoferrate(III) was applied as the redox probe in SECM; the visualization of the deposited AgNP spots was enabled by using a competition between the SECM tip microelectrode and the modified carbon plate for the oxidation of ferrocyanide. This SECM strategy proved to be an efficient tool for the interrogation of sensing surfaces that were amplified by enzyme-catalyzed silver deposition.

Reactivation of HIF prolyl hydroxylase 2 from E.coli inclusion bodies

Hypoxia inducible factor (HIF) prolyl hydroxylases (PHD) belong to α-ketoglutarate-dependent non-heme iron dioxygenases catalyzing hydroxylation of HIF prolines. The catalytic domains of all three enzyme isoforms (PHD1–3) were expressed in E.coli with the highest expression level being observed for the PHD2 isoform. In all cases, the recombinant portion of protein was mainly expressed as insoluble inclusion bodies. PHD was reactivated by refolding from inclusion bodies. To optimize the refolding procedure, a novel continuous assay based on measurement of ferrocyanide oxidation activity in the presence of HIF peptide or protein was developed. The comparison between the purified soluble enzyme samples and the PHD2 samples reactivated from inclusion bodies showed a 4–5-fold higher specific activity of the latter (5 mol min−1 vol) in the α-ketoglutarate consumption determined by fluorescence detection of ketoglutarate—o-phenylene diamine adduct. The PHD2 isoform is highly hydrophobic, has to be handled in high-molarity buffer solutions to prevent aggregation and precipitation, and is inactivated rapidly in the absence of dithiothreitol (DTT).

Tuning the electrochemical swelling of polyelectrolyte multilayers toward nanoactuation.

We discuss physicochemical determinants of electrochemical polyelectrolyte multilayer swelling that are relevant to actuator usage. We used electrochemical quartz crystal microbalance with dissipation monitoring (EC-QCM-D) and cyclic voltammetry to compare the electrochemical swelling of two types of ferrocyanide-containing polyelectrolyte multilayers, poly(l-glutamic acid)/poly(allylamine hydrochloride) (PGA/PAH), and carboxymethyl cellulose/poly(diallyldimethylammonium chloride) (CMC/PDDA). We showed that ferrocyanide oxidation causes the swelling of PGA/PAH multilayers whereas it results in the contraction of CMC/PDDA multilayers. This behavior can be attributed to the presence of a positive and a negative Donnan potential in the case of PGA/PAH and CMC/PDDA multilayers, respectively. Using multilayers consisting of PGA and poly(allylamine) ferrocene (PGA/PAH-FC), we applied EC-QCM-D and demonstrated potentiostatic thickness control with nanometer precision and showed that the multilayer's thickness depends linearly on the applied potential within a certain potential range.

Electric field effects on current–voltage relationships in microfluidic channels presenting multiple working electrodes in the weak-coupling limit

While electrochemical methods are well suited for lab-on-a-chip applications, reliably coupling multiple, electrode-controlled processes in a single microfluidic channel remains a considerable challenge, because the electric fields driving electrokinetic flow make it difficult to establish a precisely known potential at the working electrode(s). The challenge of coupling electrochemical detection with microchip electrophoresis is well known; however, the problem is general, arising in other multielectrode arrangements with applications in enhanced detection and chemical processing. Here, we study the effects of induced electric fields on voltammetric behavior in a microchannel containing multiple in-channel electrodes, using a Fe(CN) 6 3/4− model system. When an electric field is induced by applying a cathodic potential at one in-channel electrode, the half-wave potential (E 1/2) for the oxidation of ferrocyanide at an adjacent electrode shifts to more negative potentials. The E 1/2 value depends linearly on the electric field current at a separate in-channel electrode. The observed shift in E 1/2 is quantitatively described by a model, which accounts for the change in solution potential caused by the iR drop along the length of the microchannel. The model, which reliably captures changes in electrode location and solution conductivity, apportions the electric field potential between iR drop and electrochemical potential components, enabling the study of microchannel electric field magnitudes at low applied potentials. In the system studied, the iR component of the electric field potential increases exponentially with applied current before reaching an asymptotic value near 80 % of the total applied potential. The methods described will aid in the development and interpretation of future microchip electrochemistry methods, particularly those that benefit from the coupling of electrokinetic and electrochemical phenomena at low voltages.

Highly disparate activity regions due to non-uniform potential distribution in microfluidic devices: Simulations and experiments

In a microfluidic flow cell activity pattern can occur along a thin band electrode due to the potential distribution in the cell. For quantitative characterization of the pattern formation exclusively due to electric effect and for elimination of interactions of reaction sites from concentration distribution along the flow channel, a partial differential equation model is formulated for the spatiotemporal variation of electrode potential with Butler–Volmer kinetics limited by mass transfer. At constant applied circuit voltage, with increase of the electrode size a limiting current is achieved because of the spatial pattern formation. The limiting current arises due to the formation of high activity at the downstream edge, and low (nearly open circuit potential) activity at the upstream edge. The spatial pattern (e.g., ratio of active vs. inactive region) depends on the electrode size, the applied voltage, the conductivity of the electrolyte, and the distance from the downstream electrode edge to the reservoir. It is also shown that by placing equally spaced insulating stripes on the electrode much of the activity can be retained and the current does not decrease significantly due to the lessened surface area (as long as the surface area of the insulating stripes is less than about 50% of the entire electrode area). The model simulations are interpreted with a coupled ordinary differential equation model of segmented electrodes and the occurrence of the strong edge effects is confirmed with experiments of a four-electrode electrode array in a microfluidic flow cell with ferrocyanide oxidation.

Thermal switching of redox reactions at gold electrodes

Gold electrodes as one of the most common electrode materials e.g. in devices or chemical sensors are the subject of detailed studies on their surfaces with respect to passivation by very thin oxide layers. Here, we show that the passivating effect of oxide layers on gold can be switched on and off by changing the temperature of the electrode at a fixed potential. Formation and deletion of passivating oxide layers as fast processes can be changed rapidly at heated gold electrodes. Consequently, thermal switching can be performed with high frequency. Examples are given where homogeneous redox reactions are changed by switching the passive films e.g. for the oxidation of ferrocyanide, hydrogen peroxide or ferrocene. Furthermore, the reversible anodic oxidation of gold in the presence of chloride ions can be switched thermally as well. The processes contributing to passivation or depassivation, respectively, have been studied by standard as well as novel thermoelectrochemical methods like TPV (temperature pulse voltammetry). It is shown that temperature variation is an additional parameter to enhance the performance of electrochemical processes at solid electrodes.

Trapping of redox-mediators at the surface of Chlorella vulgaris leads to error in measurements of cell reducing power

The reduction of the redox mediator ferricyanide, [Fe(CN)6](3-), by a range of algal and bacterial species, is frequently measured to probe plasma membrane ferrireductase activity or to quantify the reducing power of algal/bacterial biofilms and suspensions. In this study we have used rotating disk electrochemistry (RDE) to investigate the reduction of ferricyanide by the model organism Chlorella vulgaris. Importantly, we have seen that the diffusion limited current due to the oxidation of ferrocyanide, [Fe(CN)6](4-), at the electrode decreased linearly as C. vulgaris was added to the solution, even though in a pure ferrocyanide solution the algae are not able to reduce the mediator further and are simply spectator 'particles'. We attribute this effect to trapping of ferrocyanide at the cell surface, with up to 14% of the ferrocyanide missing from the solution at the highest cell concentration. The result has important implications for all techniques that use electrochemistry and other concentration dependent assays (e.g. fluorescence and colourimetry) to monitor ferrocyanide concentrations in the presence of both biofilms and cell suspensions. Analyte trapping could lead to a substantial underestimation of the concentration of reduced product.

Interdigitated ring electrodes: Theory and experiment

The oxidation of potassium ferrocyanide, K4Fe (CN)6, in aqueous solution under fully supported conditions is carried out at interdigitated band and ring electrode arrays, and compared to theoretical models developed to simulate the processes. Simulated data is found to fit well with experimental results using literature values of diffusion coefficients for Fe(CN)64- and Fe(CN)63-. The theoretical models are used to compare responses from interdigitated band and ring arrays, and the size of ring array required to approximate the response to a linear band array is investigated. An equation is developed for the radius of ring required for a pair of electrodes in a ring array to give a result with 5% of a pair of electrodes in a band array. This equation is found to be independent of the scan rate used over six orders of magnitude.

Electrochemical and microfabrication strategies for remotely operated smart chemical sensors: Application of anodic stripping coulometry to calibration-free measurements of copper and mercury

Remote unattended sensor networks are increasingly sought after to monitor the drinking water distribution grid, industrial wastewater effluents, and even rivers and lakes. One of the biggest challenges for application of such sensors is the issue of in-field device calibration. With this challenge in mind, we report here the use of anodic stripping coulometry (ASC) as the basis of a calibration-free micro-fabricated electrochemical sensor (CF-MES) for heavy metal determinations. The sensor platform consisted of a photo-lithographically patterned gold working electrode on SiO2 substrate, which was housed within a custom stopped-flow thin-layer cell, with a total volume of 2–4μL. The behavior of this platform was characterized by fluorescent particle microscopy and electrochemical studies utilizing Fe(CN)63−/4− as a model analyte. The average charge obtained for oxidation of 500μM ferrocyanide after 60s over a 10 month period was 176μC, corresponding to a volume of 3.65μL (RSD=2.4%). The response of the platform to copper concentrations ranging from 50 to 7500ppb was evaluated, and the ASC results showed a linear dependence of charge on copper concentrations with excellent reproducibility (RSD≤2.5%) and accuracy for most concentrations (≤5–10% error). The platform was also used to determine copper and mercury mixtures, where the total metallic content was measurable with excellent reproducibility (RSD≤4%) and accuracy (≤6% error).

An amperometric biosensor for glucose detection from glucose oxidase immobilized in polyaniline–polyvinylsulfonate–potassium ferricyanide film

In this study, a novel amperometric glucose biosensor with immobilization of glucose oxidase on electrochemically polymerized polyaniline–polyvinylsulphonate–potassium ferricyanide (Pani–Pvs–Fc) films has been accomplished via the entrapment technique. Potassium ferricyanide was used as the mediator. Determination of glucose was carried out by the oxidation of potassium ferrocyanide at 0.3 V vs. Ag/AgCl. The effects of pH and temperature were investigated, and the optimum pH value was found to be 7.5. The storage stability and the operational stability of the enzyme electrode were also studied.

Simple and multi-configurational flow-cell detector for UV–vis spectroelectrochemical measurements in commercial instruments

An original, simple and sensitive flow-detector for quantitative determination by electrochemical, UV–vis absorption or spectro-electrochemical techniques has been developed. It allows variable configurations for use in a number of analytical situations besides the possibility to use different types of electrodes and materials. The dimensions and format of the detector are suitable for fitting in a standard cell holder for macro cuvettes in commercial UV–vis spectrometers. The sensor has been verified as an optical detector measuring absorbance at 420nm, due to ferricyanide, with a linear relationship for molar concentrations of between 10−5 and 10−3, with dispersions in the measurements of less than 1%. As an electrochemical detector, two different working electrodes, one made with a stainless steel (SS) pipe and another based on an indium tin oxide (ITO) layer, have been tested by measuring the current due to the oxidation of ferrocyanide while a constant potential is applied. The best results were obtained using the ITO layer because the SS electrode produces distorted chromatographic signals. Lastly, it was tested as a spectro-electrochemical sensor for both electrodes following absorbance at 420nm of the ferricyanide electro-generated in the detector from the oxidation of injected ferrocyanide. Here, the best results were obtained using the SS electrode with a linear behaviour ranging from 1.2×10−4M to 5×10−3M and dispersions of 5.4% in terms of % RSD.

High Rate Detection of Volatile Products Using Differential Electrochemical Mass Spectrometry: Combining an Electrode-Coated Membrane with Hydrodynamic Flow in a Wall-Tube Configuration

We present an experimental system that combines differential electrochemical mass spectrometry with hydrodynamic flow consisting of an impinging jet in a wall-tube configuration. This assembly allows simultaneous detection of electrochemical signals along with monitoring of dissolved gas species using differential electrochemical mass spectrometry under well-defined hydrodynamic conditions and over a wide range of mass transfer rates. The working electrode is deposited directly onto a thin, hydrophobic membrane, which also serves as the inlet to the mass spectrometer. This inlet provides extremely rapid mass detection as well as a high flux of products from the electrode surface into the mass spectrometer. The impinging jet is designed in a wall-tube configuration, in which the jet diameter is large compared to the electrode diameter, thus providing uniform and rapid mass transfer conditions over the entirety of the electrode surface. This combination of rapid detection and controllable flow conditions allows a wide range of hydrodynamic conditions to be accessed with simultaneous electrochemical and mass spectrometric detection of dissolved gas species, which is important in the analysis of a range of electrochemical reactions. The capabilities of this configuration are illustrated using a platinum-coated electrode and several electrochemical reactions, including ferrocyanide oxidation, proton reduction, and oxalic acid oxidation.

Quantitative Examination of Aqueous Ferrocyanide Oxidation in a Carbon Nanotube Electrochemical Filter: Effects of Flow Rate, Ionic Strength, and Cathode Material

The unique conductivity, small diameter, and high specific surface area of carbon nanotubes (CNTs) make them suitable for a range of nontraditional electrode structures. For example, an electrochemically active CNT microfilter has been shown to be effective for water treatment. The forced convection through the 3D CNT electrode improves mass transfer relative to conventional 2D electrodes, but the effects of several solution and reactor parameters in this system are poorly understood because previous works focused on strongly sorbing organic species capable of undergoing several multielectron transfer reactions. Here, the use of Fe(CN)64–/3– as a model soluble and nonadsorbing redox system enabled a near complete accounting of the predominant electron transfer reactions of anodic Fe(CN)64– oxidation and cathodic water reduction to H2. Subsequently, the effects of liquid flow rate, electrolyte concentration, target molecule concentration, anode potential, and cathode material on anodic Fe(CN)64– oxidation kinetics and thermodynamics in an electrochemical filter were investigated. Electrochemical kinetics were observed to increase linearly with increasing flow rate, and electrolyte concentration had negligible effects in the flow configuration due to convective replenishment of Fe(CN)64– and electrolyte to the CNT surface. In the electron-transfer-limited regime ([Fe(CN)64–]0 = 15 mM), a rate constant for the oxidation of Fe(CN)64– was calculated to be in the range ket = 2332–3705 s–1 or (6–10) × 10–3 cm s–1. The use of a CNT network cathode furthermore enabled the cathodic reaction to proceed at a lower cell potential, indicating that the CNT network catalyzed water reduction. The total cell potential required for facile water reduction decreased from 1.6 V with the Ti cathode to 0.8 V with the CNT cathode, resulting in a total cell energy efficiency (>75%) that approached the current efficiency. Overall, the results quantitatively exemplify some of the advantages of using a 3D CNT electrode in the flow-through configuration.