Ferrocyanide Ions Research Articles

Zinc‐Ferricyanide Flow Batteries Operating Stably under −10 °C

AbstractAlkaline ferri/ferro‐cyanide‐based flow batteries are well suited for energy storage because of their features of high electrochemical activity, good kinetics and low material cost. However, they suffer from low energy density and poor temperature adaptability. The ferri/ferro‐cyanide catholyte exhibits low solubility (~0.4 M at 25 °C) in NaOH‐ or KOH‐based supporting electrolyte and can easily form precipitates below room temperature. Here we report a lithium‐based supporting electrolyte that significantly enhances the solubility of ferrocyanide. The use of LiOH intensifies the ion‐dipole interaction between water molecules and solutes and cripples polarization among ferrocyanide ions. Thus, we have achieved a ferrocyanide‐based catholyte of 1.7 M at 25 °C and of 0.8 M at −10 °C. A zinc‐ferricyanide flow battery based on the lithium‐based supporting electrolyte demonstrates a steady charge energy of ~72 Wh L−1catholyte at 25 °C, and maintains stable for ~4200 cycles (~4200 hours). Furthermore, it remains stable for ~800 cycles (~800 hours) at −10 °C.

In situ green architecture of the 3D FeZn-N-C based electrocatalyst for efficient oxygen reduction.

We prepared a 3D FeZn-N-C based catalyst by green in situ growth of 1D Fe-N-C carbon nanotubes by introducing ferrocyanide ions on the surface of 2D exfoliated MOF-5. The 1D/2D FeZn-N-C based electrocatalyst is conducive to O2 diffusion and ionic/electron transfer, exhibiting an excellent ORR catalytic performance and a peak power density of 294 mW cm-2 for Zn-air batteries.

Unlocking the electrochemical performance of glassy carbon electrodes by surface engineered, sustainable chitosan membranes

Chitosan coatings, derived from crustacean shell waste, possess inherent biocompatibility and biodegradability, rendering them suitable for various biomedical and environmental applications, including electrochemical biosensing. Its amine and hydroxyl functional groups offer abundant sites for chemical modifications to boost the charge transfer kinetics and provide excellent adhesion, enabling the construction of robust electrode-coating interfaces for electroanalysis. This study explores the role of electrostatically-driven chemical interactions and crosslinking density originating from different chitosan (Cs) and glutaraldehyde (Ga) concentrations in this aspect. Studying anionic ([Fe(CN)6]3−/4−), neutral (FcDM0/+), and cationic ([Ru(NH3)6]2+/3+) redox probes highlights the influence of Coulombic interactions with chitosan chains containing positively-charged pathways, calculated by DFT analysis. Our study reveals how a proper Ch-to-Ga ratio has a superior influence on the cross-linking efficacy and resultant charge transfer kinetics, which is primarily boosted by up to 20× analyte preconcentration increase, due to electrostatically-driven migration of negatively charged ferrocyanide ions toward positively charged chitosan hydrogel. Notably the surface engineering approach allows for a two-orders of magnitude enhancement in [Fe(CN)6]4− limit of detection, from 0.1 µM for bare GCE down to even 0.2 nM upon an adequate hydrogel modification.

Leaching behaviour of a crystallisation inhibitor in mortars

This paper investigates the leaching behaviour of sodium ferrocyanide, a known crystallisation inhibitor of sodium chloride, which is added to mortars for mitigation of salt decay. Leaching and depletion of the inhibitor is a practical performance related issue that might over time, make the inhibitor less effective against salt decay. In this research, the inhibitor was added to natural hydraulic lime (NHL) mortars during the mixing stage. Leaching of the inhibitor from the hardened mortar was assessed experimentally in laboratory. Both diffusion- and advection-driven transport mechanisms were considered. Diffusion experiments were carried out in a tank leaching test setup. Capillary absorption and drying cycles were used as a driving force to study advection-driven transport. Quantification of the leached species was carried out using various analytical techniques, including UV-VIS spectroscopy, ICP-OES and ion chromatography. The results from the tank leaching test show a high effective diffusion coefficient of ferrocyanide ions, in the same order of magnitude as sodium chloride transport. The advection test shows accumulation of the inhibitor at the evaporative surface and depletion of the inhibitor in the inner layers with successive wet-dry cycles. Based on these results it can be inferred that the degree of inhibitor leaching is significant and needs to be minimised to prolong the positive effect of the inhibitor on mortar durability. Potential solutions to reduce inhibitor leaching are discussed.

In Situ Fe-Substituted Hexacyanoferrate for High-Performance Aqueous Potassium Ion Batteries.

The eco-friendliness, safety, and affordability of aqueous potassium batteries (AKIBs) have made them popular for large-scale energy storage devices. However, the cycling and rate performance of research materials, particularly cobalt hexacyanoferrate, have yet to meet satisfactory standards. Herein, a room-temperature drafted K1.66 Fe0.25 Co0.75 [Fe(CN)6 ]·0.83H2 O (KFCHCF) sample is reported using an in situ substitution strategy. A higher concentration of ferrocyanide ions decreases the water content and increases the potassium content, while citric acid works as a chelating agent and is responsible for Fe-substitution in the KFCHCF sample. The resultant KFCHCF sample exhibits good rate performance, and about 97% and 90.6% of discharge capacity are conserved after 400 and 1000 cycles at 100 and 200mA g-1 , respectively. The full cell using the KFCHCF cathode and 1,4,5,8-naphthalenetetracarboxylic dianhydride-derived polyimide (PNTCDA) anode maintains ≈74.93% and 74.35% of discharge capacity at 200mA g-1 and 1000mA g-1 for 1000 and >10,000 cycles, respectively. Furthermore, ex situ characterizations demonstrate the high reversibility of K-ions and structural stability during the charge-discharge process. Such high performance is attributed to the fast K-ion migration and crystal structure stabilization caused by in situ Fe-substitution in the KFCHCF sample. Other hexacyanoferrates can be synthesized using this method and used in grid-scale storage systems.

A multimode detection of silver ions based on peroxidase-like activity and photothermal effect of Prussian blue nanoparticles

Silver ion (Ag+), as a heavy metal ion easily absorbed by organisms, can be enriched through the food chain. This study present a novel multimodal detection system for Ag+ using Prussian blue nanoparticles (PB NPs) with excellent photothermal effect and peroxidase-like activity. The PB NPs undergo a dissolution-precipitation equilibrium, converting blue PB NPs into colourless silver ferrocyanide ions in the presence of Ag+. The color, photothermal effect, and peroxidase-like activity of the PB NPs change with the concentration of Ag+, making them an effective probe for detecting Ag+. The key parameters that affect the performance of multimode detection assay were optimized. Under optimal conditions, the detection limit of visual detection was estimated to be 2.94 μM. Based on catalytic color development and the photothermal effect of PB NPs, the detection limit of color development detection and photothermal analysis were reduced to 0.57 μM and 0.23 μM, respectively. And the detection range was also broadened than visual direct detection. Besides, the multimode detection of Ag+ improves the accuracy of detection by mutual verification. The promising multimode system exhibited good repeatability and specificity of Ag+ in different sample implementations, which has great potential for applications in food safety regulation and environmental monitoring.

Post-Synthetic Cyano-ferrate(II) Functionalization of a Metal–Organic Framework, NU-1000

Starting with ferrocyanide ions in acidic aqueous solution, cyano-ferrate(II) species are post-synthetically grafted to the nodes of a mesoporous zirconium-based MOF, NU-1000. As indicated by single-crystal X-ray crystallography, grafting occurs by substitution of cyanide ligands by node-based hydroxo and oxo ligands rather than by substitution of node aqua ligands by cyanide ligands as bridges between Fe(II) and Zr(IV). The installed moieties yield a broad absorption band that is tentatively ascribed to iron-to-zirconium charge transfer. Consistent with Fe(III/II) redox activity, a modest fraction of the installed iron complexes are directly electrochemically addressable.

Ferrocyanide enhanced evaporative flux to remediate soils contaminated with produced water brine.

Accidental releases of highly saline produced water (PW) to land can impact soil quality. The release of associated salts can clog soil pores, disperse soil clays, and inhibit plants and other soil biota. This study explores a novel remediation technique using ferrocyanide to enhance the evaporative flux of soil porewater to transport dissolved salts to the soil surface, where crystallization then occurs. The addition of ferrocyanide modifies crystal growth that enhances salt transport, allowing salt efflorescence on the soil surface and physical removal. Release sites were simulated through beaker sand column experiments using two PWs collected from the Permian Basin. PW composition altered efflorescence, with up to ten times as much ferrocyanide required in PWs than comparable concentrations of pure NaCl solutions. The addition of EDTA reduced dissolved cation competition for the ferrocyanide ion, improving PW salt recovery at the soil surface. The speciation model, PHREEQC, was used to predict the onset of salt precipitation as a function of evaporative water loss and model the effect of aqueous ferrocyanide and EDTA speciation on efflorescence. The results highlight the utility of predictive modeling for optimizing additive dosages for a given release of PW.

States of Aggregation and Phase Transformation Behavior of Metallosurfactant Complexes by Hexacyanoferrate(II): Thermodynamic and Kinetic Investigation of ETR in Ionic Liquids and Liposome Vesicles.

Electronic absorption spectroscopy was used to study the ETR of surfactant-cobalt(III) complexes containing imidazo[4,5-f][1,10]phenanthroline, dipyrido[3,2-d:2'-3'-f]quinoxaline and dipyrido[3,2-a:2',4'-c](6,7,8,9-tetrahydro)phenazine ligands by using ferrocyanide ions in unilamellar vesicles of dipalmitoylphosphotidylcholine (DPPC) and 1-butyl-3-methylimidazolium bromide ((BMIM)Br), at different temperatures under pseudo-first-order conditions using an excess of the reductant. The reactions were found to be second-order and the electron transfer is postulated as occurring in the outer sphere. The rate constant for the electron transfer reactions was found to increase with increasing concentrations of ionic liquids. Besides these, the effects of surfactant complex ions on liposome vesicles in these same reactions have also been studied on the basis of hydrophobicity. We observed that, below the phase transition temperature, there is an increasing amount of surfactant-cobalt(III) complexes expelled from the interior of the vesicle membrane through hydrophobic effects, while above the phase transition temperature, the surfactant-cobalt(III) complexes are expelled from the interior to the exterior surface of the vesicle. Kinetic data and activation parameters are interpreted in respect of an outer-sphere electron transfer mechanism. By assuming the existence of an outer-sphere mechanism, the results have been clarified based on the presence of hydrophobicity, and the size of the ligand increases from an ip to dpqc ligand and the reactants become oppositely charged. In all these media, the ΔS# values are recognized as negative in their direction in all the concentrations of complexes employed, indicative of a more ordered structure of the transition state. This is compatible with a model in which these complexes and [Fe(CN)6]4- ions bind to the DPPC in the transition state. Thus, the results have been interpreted based on the self-aggregation, hydrophobicity, charge densities of the co-ligand and the reactants with opposite charges.

Optimizing NH4+ Storage Capability of Nickel Ferrocyanide by Regulating Coordination Anion in Aqueous Electrolytes

AbstractWill anions in electrolytes affect the electrochemical properties of Prussian blue analogues for aqueous ammonium ion batteries? In this study, the electrochemical reaction between nickel ferrocyanide and ammonium ions is investigated in three common inorganic ammonium salt solutions [NH4NO3, NH4Cl, and (NH4)2SO4]. The results suggest that at the same NH4+ concentration, nickel ferrocyanide exhibits different electrochemical performances. The as‐prepared nickel ferrocyanide contains two phases, which are rhombohedral phase and cubic phase. Rhombohedral phase of nickel ferrocyanide has a high reactivity in 0.5 M (NH4)2SO4 solution during cycling while cubic phase shows good performance in 1 M NH4NO3 and 1 M NH4Cl electrolyte. It should be noted that the performance of cubic phase is superior to rhombohedral phase in kinetic consideration. Additionally, due to the strong coordination ability of chloride, nickel ferrocyanide exhibits an excellent electrochemical performance in 1 M NH4NO3 solution, rather than 1 M NH4Cl electrolyte.

The effect of a sulfonated naphthalene-based polymer on redox reaction data, potassium ferrocyanide complexation, and the compressive strength of Portland cement paste

In this work, the effect of sulfonated naphthalene-based polymer (Sikament) on redox reactions of potassium ferrocyanide and the compressive strength of Portland Cement paste was investigated. Cyclic voltammetry of sulfonated naphthalene-based polymers with different concentrations was measured experimentally using a DY2000 potentiostat. We used KCl (0.1 M) as a supporting electrolyte. A glassy carbon working electrode was used, purified, and polished before use. The other two electrodes are platinum wire and Ag/AgCl electrodes put in saturated KCl solution were used. The interaction of sulfonated naphthalene-based polymer and potassium ferrocyanide was studied with the use of different potassium ferrocyanide concentrations at 290.65 K. The oxidation, reduction mechanisms and the stability constants of the complexes formed are discussed. Scan rates and different kinetic parameters that resulted from this interaction were also evaluated and their values were discussed. The compressive strength for each paste at different time intervals (1, 3, 7 and 28 days) was determined. The results showed clearly that the polymer is combined with the iron and thus increases its compressive strength and decreases iron oxidation. Complexation was observed from the interaction thermodynamic data resulting from the interaction of the used polymer and ferrocyanide ion.

Adapting confocal Raman microscopy for in situ studies of redox transformations at electrode-electrolyte interfaces

Confocal Raman microscopy was applied to quantify redox species present within the diffusion layer adjacent to an electrode surface under potentiostatic control. A glass microscope coverslip with a thin indium tin oxide (ITO) coating served as both the working electrode and optical window for a microscope-stage mountable spectroelectrochemical cell. A high numerical aperture objective mounted in an inverted microscope frame just below the stage brought excitation radiation through the coverslip window and to a tight focus a few micrometers above the ITO film surface. Species diffusing into the confocal probe volume defined by the excitation beam focus and the collected light region were detected, identified and quantified based on their Raman scattering frequencies and intensities. In measurements that interrogated the interconversion of ferrocyanide and ferricyanide ions as a function of applied voltage, least-squares regression analysis of spectral datasets predicted the formal potential and relative surface concentrations of the ions in good agreement with the expected Nernstian response. Preliminary studies of methyl viologen reduction at an ITO film/Nafion membrane interface were conducted and show the possibility for estimation of mass transport coefficients of redox species within ionic polymer materials.

Effect of Supporting Background Electrolytes on the Nanostructure Morphologies and Electrochemical Behaviors of Electrodeposited Gold Nanoparticles on Glassy Carbon Electrode Surfaces.

Electrodeposition is an electrochemical method employed to deposit stable and robust gold nanoparticles (AuNPs) on electrode surfaces for creating chemically modified electrodes (CMEs). The use of several electrodeposition techniques with different experimental parameters allow in obtaining various surface morphologies of AuNPs deposited on the electrode surface. By considering the electrodeposition of AuNPs in various background electrolytes could play an important strategy in finding the most suitable formation of the electrodeposited AuNP films on the electrode surface. This is because different electrode roughnesses can have different effects on the electrochemical activities of the modified electrodes. Thus, in this study, the electrodeposition of AuNPs onto the glassy carbon (GC) electrode surfaces in various aqueous neutral and acidic electrolytes was achieved by using the cyclic voltammetry (CV) technique with no adjustable CV parameters. Then, surface morphologies and electrochemical activities of the electrodeposited AuNPs were investigated using scanning electron microscopy (SEM), atomic force microscopy (AFM), CV, and electrochemical impedance spectroscopy (EIS). The obtained SEM and 3D-AFM images show that AuNPs deposited at the GC electrode prepared in NaNO3 solution form a significantly better, uniform, and homogeneous electrodeposited AuNP film on the GC electrode surface with nanoparticle sizes ranging from ∼36 to 60 nm. Meanwhile, from the electrochemical performances of the AuNP-modified GC electrodes, characterized by using a mixture of ferricyanide and ferrocyanide ions [Fe(CN6)3–/4–], there is no significant difference observed in the case of charge-transfer resistances (Rct) and heterogeneous electron-transfer rate constants (ko), although there are differences in the surface morphologies of the electrodeposited AuNP films. Remarkably, the Rct values of the AuNP-modified GC electrodes are lower than those of the bare GC electrode by 18-fold, as the Rct values were found to be ∼6 Ω (p < 0.001, n = 3). This has resulted in obtaining ko values of AuNP-modified GC electrodes between the magnitude of 10–2 and 10–3 cm s–1, giving a faster electron-transfer rate than that of the bare GC electrode (10–4 cm s–1). This study confirms that using an appropriate supporting background electrolyte plays a critical role in preparing electrodeposited AuNP films. This approach could lead to nanostructures with a more densely, uniformly, and homogeneously electrodeposited AuNP film on the electrode surfaces, albeit utilizing an easy and simple preparation method.

Identification of thermodiffusion coefficients in an aqueous potassium ferri/ferrocyanide thermocell using open-circuit voltage data

Ion thermodiffusion coefficients are crucial to analyse effects of thermodiffusion in thermocells and these values are difficult to measure experimentally. To determine these coefficients, this paper adopts parameter identification and studies their identifiability. Time dependence of open-circuit voltage is measured in an aqueous potassium ferri/ferrocyanide thermocell as data set. A one-dimensional numerical model is established according to theories of electrochemistry and non-equilibrium thermodynamics. Identification of thermodiffusion coefficients is conducted using genetic algorithm in eight parameter spaces, which are divided according to signs of three parameters. Thermodiffusion is suggested to induce a 9.38% drop in voltage. The best identification results are −8.30 × 10−12, −6.56 × 10−12, −3.48 × 10−12 m2/(s K) for ferricyanide, ferrocyanide and potassium ion, respectively. However, five optimal parameters in other parameter spaces have close fitness, implying multimodality of identification. And only one of these parameters is practically identifiable using this method. To improve identification results, more accurate estimation of inner temperature difference and determination of ion mobilities are necessary. Besides, electric current data has the potential to determine the actual combination of thermodiffusion coefficients from these six optimal results.

Electrochemical vanillin reduction in a plane parallel flow reactor: Characterization, modeling and process improvement

The application of electrochemical flow reactors for electrosynthetic processes on a laboratory or pilot scale has recently gained increased attention as they provide reliable and improved performance and facilitate a further scale-up. We investigated in this study the electrochemical reduction of vanillin (4-hydroxy-3-methoxybenzaldehyde) to its pinacolization product hydrovanilloin, a building block in the synthesis of biobased polymers, in a divided plane parallel flow reactor in batch recycle operation mode. First, the mass transport of the flow reactor was characterized with dimensionless groups using the ferricyanide ion / ferrocyanide ion system as model reaction. The mass transport was further improved by 3D-printed turbulence promoters. We then studied the electrochemical vanillin reduction monitored by an online UV-cell setup at various electrolyte flow rates up to 20 cm s−1 and current densities up to 50 mA cm−2 with total conversions of 95%. Key figures of merit such as Faradaic efficiencies, space-time-yields and specific energy consumptions were calculated and a simple model was used to describe vanillin concentration decays and courses of these key figures of merit. The model distinguishes between a kinetic and mass transport-controlled zone, which transition point was predicted based on the mass transport characterization results. Lastly, we developed based on the model an operational process improvement strategy for fast and energy efficient production of hydrovanilloin and validated it experimentally. This study reports a first engineering approach for the production of vanillin-based polymer building blocks in an electrochemical flow reactor highlighting the ability of simple prediction models.

Low‐cost conductive films based on graphite and cellulose acetate as promising electroanalytical platforms

AbstractConducting films were produced by incorporating 35, 50, and 60 wt.%. of graphite in cellulose acetate. The graphite contents showed to be of pivotal importance to the properties of the materials, mainly on the electrochemical performance. Thermal analyses indicated the graphite hinders the crystallization process of cellulose acetate and increases the hydrophobicity of the films. Scanning electron microscopy provided evidence of laminated graphite structures well‐dispersed in the polymeric matrix and exhibited a more porous aspect surface for the 50% G/Composite, which led to a higher surface area obtained by the N2 adsorption/desorption technique. This composite also had a better electrochemical response for ferrocyanide ion. The fabrication method was reproducible, which was associated with the structural uniformity of the resulting material. In addition, the conductive films are ready to use after production, precluding the need for any surface pretreatment. Moreover, the proposed sensor showed analytical potentiality for dopamine and hydroquinone determination, extending the possibilities for new electroanalytical applications.

Alkaline phosphatase-regulated in situ formation of chromogenic probes for multicolor visual sensing of biomarkers

Alkaline phosphatase (ALP), as an immunological label, is widely used in biochemical assays. Here, a simple yet effective strategy for ALP activity detection was proposed on the basis of in situ formation of Prussian blue nanoparticles and polychromatic superposition effect. Firstly, ascorbic acid, a product from ALP-catalyzed hydrolysis of 2-phospho-l-ascorbic acid (AAP), converted yellow ferricyanide into ferrocyanide. Then, the specific reaction between ferrocyanide and ferric ions (Fe3+) initiated the generation of Prussian blue nanoparticles in situ. Meanwhile, the residual AAP chelated with Fe3+, and a stable Fe3+-AAP complex was quickly formed. When Prussian blue nanoparticles mixed with brown Fe3+-AAP complex and yellow ferricyanide at different ratios, a distinct color variation was presented. Therefore, a sensitive multicolor assay of ALP activity with a detection limit of 1.0 U/L was realized by simply blending commercially available reagents. Furthermore, magnetic sandwich and competitive sensing platforms for multiple biomarkers detection were constructed by combining the ALP-regulated multicolor system with the well-developed aptasensor. The feasibility of the sensors was convincingly demonstrated by using thrombin and prostate specific antigen as model targets. In addition, the proposed multicolor strategy was employed for evaluating inhibition efficiency, and shows potential in visual screening of enzyme inhibitors. Such a facile, sensitive and low-cost sensing strategy provides a new perspective to develop universal platforms of point-of-care testing.

A sensitive spectrofluorimetry method based on S and N dual-doped carbon nanoparticles for ultra-trace detection of ferrocyanide ion in food salt samples

ABSTRACT An ultra-sensitive spectrofluorimetry method was developed and validated for the rapid determination of ferrocyanide ions (hexacyanidoferrate(II), FeCN6 4-, FCNs) by using sulphur (S) and nitrogen (N) dual-doped fluorescence carbon nanoparticles (S,N-FCNPs) as nanoprobe. The fluorescence of S,N-FCNPs was strongly reduced due to the dynamic interaction between S,N-FCNPs and FeCNs. The developed method proved to be highly sensitive and selective for FeCNs detection with linearity in three concentration ranges over four orders of magnitude, covering 0.01–200.0 μg/mL. A limit of detection (LOD) of 2.8 ng/mL was obtained. The method was successfully applied for the determination of FeCNs in a series of dietary food salt samples and gave satisfactory results; the spiked recoveries were 97.6‒104.6% with standard uncertainty less than 5.8%. The method proved to be applicable for ultra-trace detection of FeCNs in food salt samples, having advantages in great simplicity, rapid response, low cost, favourable selectivity, and high sensitivity.

Thermodynamics, in vitro release and cytotoxity studies on doxorubicin–toluidine blue O combination drugs co-loaded in aptamer-tethered DNA nanostructures

DNA nanostructures-based chemotherapy-phototherapy (CTPT) combination therapy can achieve targeted release and effectively overcome multidrug resistance (MDR). The therapeutic effect of CTPT combination drugs loaded in DNA nanostructures is related to the interactions among them. Herein, based on our previous research on AS1411NTrs loading with a single drug of DOX, the interactions between a single drug (toluidine blue O, TBO) or combination drugs (doxorubicin and toluidine blue O, DOX + TBO) and AS1411 aptamer-tethered DNA nanotrains (AS1411NTrs) were investigated. By fluorescence spectroscopy and isothermal titration calorimetry technique, the corresponding thermodynamic parameters were obtained, including the number of binding sites, binding constant, enthalpy change and entropy change. By combining with the differential scanning calorimetry and ferrocyanide ion quenching analysis, the binding mode-thermodynamic parameters were correlated. In addition, the effect of the binding affinity of DOX and TBO to AS1411NTrs on the drugs release rate was studied. Finally, the in vitro cytotoxicity and confocal laser scanning microscopy imaging of AS1411NTrs + TBO + DOX was investigated. The results showed that this drug delivery system could increase its in vitro cytotoxicity and overcome drug resistance in DOX-resistant human breast cancer cells (MCF-7/ADR). The work would provide important information for the combination therapy of DOX and TBO to overcome MDR effectively.

Sampled current voltammetry for kinetic studies on materials unsuitable for rotating discs or microelectrodes: Application to the oxygen reduction reaction in acidic medium

Herein, sampled current voltammetry (SCV) is exploited to study the kinetics of electrochemical reactions with electrode materials that are unsuitable for rotating disc or microelectrode experiments. The approach described opens up the possibility of assessing the electrocatalytic activity of films produced by high throughput deposition techniques, especially conducting films formed on insulators. This is particularly valuable for testing novel oxygen reduction or oxygen evolution catalysts. SCV is a transient technique, yet for processes affected by mass transport, it produces sigmoidal current-voltage curves, which can be analysed as conventional steady state voltammograms. Selecting different sampling times affords a range of mass transfer coefficients and this is particularly useful to determine kinetic parameters. The applicability of SCV is first assessed with the fast electron transfer between ferri and ferrocyanide ions and an excellent agreement between the SCV and RDE methods is found. Then, SCV is used to investigate the oxygen reduction reaction (ORR) on a stationary polycrystalline Pt disc, on a polycrystalline Pt foil and on a thin Pt film orientated in the (110) direction. The results are systematically compared with those from a rotated polycrystalline Pt disc. Importantly, the sampled current voltammograms (SCVs) are found to be sufficiently sensitive to reveal differences in electrocatalytic activity between the Pt electrodes and between different sulfate concentrations. The technique is thus well adapted to probing variations in catalytic activity due to surface structure or interactions between solution species and surface sites. For polycrystalline Pt, the ORR kinetic parameters obtained from the Koutecký-Levich (K-L) analysis of the SCVs are in good agreement with those obtained with the RDE. Overall, the sampled current voltammetry approach reported here provides a valuable alternative to steady state voltammetry, and it is particularly suited to assess the electrocatalytic properties of surfaces where epitaxial thin film electrodes are grown on insulating substrates. The methodology could easily be extended to other substrates such as catalysts deposited on gas diffusion electrodes.