Hexacyanoferrate Film Research Articles

Effect of metal hexacyanoferrate films on hydrogen evolution reaction

In this report for the first time the effect of different metal hexacyanoferrate (MHCF) films on hydrogen evolution reaction (HER) was studied. Some single and mixed MHCFs including CoHCF, CuHCF, NiHCF, PbHCF, Ba–NiHCF, Co–NiHCF, Co–PbHCF, Co–CuHCF, Cu–NiHCF, Cu–PbHCF, Mn–NiHCF, Ni–PbHCF and Ni–ZnHCF were simply electrodeposited on carbon paste electrode (CPE) and their performance for HER were examined in acidic, neutral and alkaline media. Presence of these mediators caused to improvement of hydrogen generation on CPE. Among these mediators Ni–PbHCF had the best efficiency with the lowest over potential for hydrogen evolution in 2M H2SO4. Also, applying several successive potential cycles for HER on the electrode modified with Ni–PbHCF did not reduce the performance of the electrode for hydrogen generation.

Hydrogen Peroxide Detection with n-Silicon Photoelectrodes Modified by Nickel Hexacyanoferrate Films

Hydrogen Peroxide Detection with n-Silicon Photoelectrodes Modified by Nickel Hexacyanoferrate Films

Photocurrent determination ascorbic acid using an n-silicon electrode modified by platinum and cobalt hexacyanoferrate films

By depositing a film of cobalt hexacyanoferrate (CoHCF) on silicon electrode coated by a platinum layer, a novel photoelectrochemical sensor for the detection of ascorbic acid (AA) has been developed. The stable film of CoHCF was electrochemically deposited onto a phosphorus heavy doped silicon (n+-Si) with 9 μm epitaxial layer (n–n+-Si) wafers coated with about 40 nm platinum layer (Pt/n–n+-Si). Scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectra, X-ray diffraction (XRD) and cyclic voltammetry (CV) were used to characterize the CoHCF film on the Pt/n–n+-Si electrode. The CoHCF modified Pt/n–n+-Si electrode has been used for determination of AA with a two-electrode cell in absence of reference electrode by photocurrent measurement at a zero bias. The composite modified electrode demonstrated good photocurrent responses by adding different concentrations of AA with a good stability. The linear range for the detection of AA was 1.0 × 10−6 to 1.0 × 10−3 M, with a detection limit (S/N = 3) of 1.0 × 10−6 M. This provides a facile way of detecting AA and succeeds in averting from inconvenient reference electrode.

Enhancement of stability of Prussian blue thin films by electrochemical insertion of Ni2+ ions: A stable electrocatalytic sensing of H2O2 in mild alkaline media

Electrocatalytic films of mixed (substitutional) nickel–iron hexacyanoferrate with the Ni/Fe molar ratio up to 0.13 were prepared by incorporation of Ni2+ ions into the structure of electrochemically deposited thin Prussian blue films. The obtained films retained the high electrocatalytic activity inherent to Prussian blue and were stable towards degradation in alkaline media up to pH 9.3, enabling the sensing of 5×10−8 to 2×10−4mol/dm3 of H2O2 at pH 9.0, with the sensitivity of 1.14AM−1cm−2 and the detection limit of 2×10−8mol/dm3. Based on the results of electrochemical, XPS, and SEM investigations, the stability of mixed nickel–iron hexacyanoferrate films at pH 9.0 was attributed to the hydrolysis-induced lattice transformation occurring at the film/solution interface and resulting in the formation of a thin and compact layer of an alkaline-stable nickel hexacyanoferrate, which covers the remaining nickel–iron hexacyanoferrate film and protects it from further degradation.

Voltammetric Determination of Captopril Employing Platinum Electrode Modified with Iron (III) Hexacyanoferrate (II) Film

Environment contamination with drugs even at concentrations in the order mg L-1 and ng L-1 culminates in environmental and public health problems because these substances are biologically active. For this reason, the pursuit of instrumental methods for the determination of these substances has been the main target of several investigators. Captopril, an antihypertensive drug employed for the treatment of heart failure, has been identified by means of electrochemical technique. To this end, a platinum electrode modified with an iron (III) hexacyanoferrate (II) film (Prussian blue) associated with the cyclic voltammetry mode has been utilized. Our results have furnished a linear correlation coefficient (r) of 0.998 with a standard deviation (SD) of 0.007 μA, a detection limit (based on the 3 SD/m ratio) in 7 µmol L-1, and a quantification limit (based on the relationship 10 SD/m) of 23.3 µmol L-1.

Structural characterization of electrodeposited copper hexacyanoferrate films by using a spectroscopic multi-technique approach

A deep structural investigation predominantly by X-ray spectroscopic techniques is conducted on films of copper hexacyanoferrate (CuHCF) deposited under different conditions, aimed at establishing structure-properties relationships. We show that the potentiodynamic electrosynthesis of CuHCF on carbon-based surfaces produces a highly disordered material, with a variable amount of Prussian Blue (PB). The subsequent Cu(2+) intercalation induces the partial conversion of PB into CuHCF, which explains the improved electrocatalytic properties after the intercalation process. Both Cu and Fe K-edge data have been recorded. For the sample with the lower amount of PB, we could perform a multiple edge data analysis to determine the local atomic environment around both metal centres using the same set of structural parameters. The presence of high multiplicity Cu-N-C-Fe linear chains has allowed us to determine accurately the local environment of Fe while fitting the Cu K-edge data only. Using this approach we have retrieved structural information around Fe for those samples in which the concomitant presence of PB would have made impossible the analysis of the Fe K-edge. The Fe-C, C-N and Cu-N bond distances have been found in agreement with those of the bulk structures, but higher values of [Fe(CN)(6)] vacancies for the building blocks have been evidenced, reaching a value of ~45% in one sample. XANES, Raman and SEM data agree with the model proposed for each studied electrode.

Electrocatalytic Oxidation of Guanine and Adenine Based on Iron Hexacyanoferrate Film Modified Electrodes

Electrocatalytic Oxidation of Guanine and Adenine Based on Iron Hexacyanoferrate Film Modified Electrodes

Sorption of hydrogen onto titanate nanotubes decorated with a nanostructured Cd 3[Fe(CN) 6] 2 Prussian Blue analogue

Nanostructured films of cadmium hexacyanoferrate (III), Cd 3[Fe(CN) 6] 2 have been deposited on the surface of titanate nanotubes (TiNT) by ion exchange with CdSO 4, followed by reaction with K 3[Fe(CN) 6] in an aqueous suspension. The composite demonstrates a significantly higher hydrogen storage uptake than pure Cd 3[Fe(CN) 6] 2 and TiNT. At a temperature of 77 K and a pressure 100 bar, the hydrogen uptake for the composite is approximately 12.5 wt %, whereas only 4.5 wt % and 4 wt % are achieved for the TiNT and Cd 3[Fe(CN) 6] 2 respectively. Electron microscopy and infrared spectroscopy show that Cd 3[Fe(CN) 6] 2 is uniformly distributed on the surface of the nanotubes forming a discontinuous nanostructured film with a well developed interface, which allows efficient interaction with the support. The possible reasons for the high uptake of hydrogen in the composite are discussed.

Unipolar pulse electrodeposition of nickel hexacyanoferrate thin films with controllable structure on platinum substrates

Unipolar pulse electrodeposition was used to prepare nickel hexacyanoferrate (NiHCF) films on platinum substrates with controllable structure. The unipolar pulse waveforms consisted of an applied cathodic potential during the on-period and the open-circuit potential during the off-period. The effects of the pulse deposition parameters on the electrochemical properties of NiHCF films were investigated by potential cycling in K+-containing electrolytes. The morphology and composition of NiHCF films were characterized using scanning electron microscopy and energy dispersive X-ray spectroscopy. The charge transfer and the stability of the film electrodes were also examined by cyclic voltammetry (CV). Experimental results show that the cathodic pulse potential is the primary factor influencing the composition of the NiHCF films. The structure of NiHCF films prepared with a pulse potential of 0.7V SCE appears close to that of the “insoluble” form with a single reversible CV peak at lower voltage and a unit cell with a stoichiometry close to KNi4II[FeIII(CN)6]3. These films exhibit good stability and high dynamics for charge transport. The application of more negative cathodic potential pulses produces less dense and robust NiHCF films, with a structure closer to the “soluble” form and an approximate stoichiometry K8Ni4II[FeII(CN)6]4.

Simple and reliable biosensor for determination of glucose in alcoholic beverages

The objective of this work was to determine the glucose in alcoholic beverages using the simple and reliable glucose oxidase (GOx) biosensor. Glucose oxidase was immobilized on the surface of modified graphite electrode in mixed photocurable polymeric membranes of polyacrylamide (PAA)/polyvinylpyrolidone (PVP), taking advantage of both immobilizations; higher activity due to enzyme entrapment (PVP) and longer life of biosensor due to covalent bonding of enzyme (PAA). The surface of graphite electrode was modified with electrodeposited layer of indium (III) and ruthenium (III) hexacyanoferrate films to get faster electron transfer through the surface layer of the modified electrode. Voltammetric and amperometric measurements were performed under batch conditions.The response of biosensor was measured as a function of selected organic solvents (methanol, ethanol and isopropanol) containing phosphate buffer solution (pH=6.5) at −100mV against a reference Hg∣Hg2Cl2∣3M KCl electrode. Addition of 10% of methanol and ethanol increased, while higher volume fractions decreased the biosensor response. On the other hand isopropanol (10%) decomposed the photopolymeric membrane. Therefore, the determination of glucose in alcoholic beverages has been performed in phosphate buffer with 10% of ethanol. The linear range was obtained up to 0.8mM (R2=0.9925) for mixed solvents, as well as phosphate buffer (R2=0.9996).The simple, fast and easy preparation of the biosensor, high activity and long life, if glucose was immobilized in mixed polymeric photocurable membrane, and reasonably accurate glucose determination, make the proposed procedure appropriate for quality control of the alcoholic beverages in mixed solvents.

A novel hydrazine electrochemical sensor based on a zirconium hexacyanoferrate film-bimetallic Au–Pt inorganic–organic hybrid nanocomposite onto glassy carbon-modified electrode

This work describes the electrochemical behavior of zirconium hexacyanoferrate (ZrHCF) film immobilized on the surface of bimetallic Au–Pt inorganic–organic hybrid nanocomposite glassy carbon electrode and its electrocatalytic activity toward the oxidation of hydrazine. The electrode possesses a three-dimensional (3D) porous network nano architecture (NFs). The surface structure and composition of the sensor was characterized by scanning electron microscopy (SEM). Electrocatalytic oxidation of hydrazine on the surface of modified electrode was investigated with cyclic voltammetry and chronoamperometry methods and the results showed that the ZrHCF film displays excellent electrochemical catalytic activities toward hydrazine oxidation. The modified electrode indicated reproducible behavior and high level of stability during the electrochemical experiments.

Ni x–Fe (1−x)Fe(CN) 6 hybrid thin films electrodeposited on glassy carbon: Effect of tuning of redox potentials on the electrocatalysis of hydrogen peroxide

The electrochemical deposition of mixed Ni x –Fe (1− x )Fe(CN) 6 thin films on a glassy carbon (GC) electrode surface were carried out by electro-deposition under continuous potential cycling condition for the first time. The redox potential of the low spin iron in the hybrid film was found to depend on the ratio of metal centres. The improvement in the electrocatalytic property of the nickel hexacyanoferrate film with incorporation of iron ions in the film towards the electrocatalysis of hydrogen peroxide was studied in electrolytes like KNO 3 and NaNO 3. The stability of hybrid film in Na + containing supporting electrolytes was examined. Detection limit of H 2O 2 was about 1 μM as determined by amperometry with the sensitivity of 192 nA/μM. The chemically modified glassy carbon electrodes with Ni x Fe (1− x )HCF hybrid films were characterized by cyclic voltammetry, impedance spectroscopy, energy dispersive X-ray analysis etc. These films may find extensive applications as redox mediators in biosensors which employ oxidase enzymes.

Electrocatalytic oxidation of l-tryptophan using copper hexacyanoferrate film modified gold nanoparticle graphite-wax electrode

A novel copper hexacyanoferrate (CuHCF) film modification on cysteamine (Cys)-gold nanoparticle (AuNp) graphite-wax (GW) composite electrode was achieved for the quantitative determination of L-Tryptophan (L-Trp) at a reduced overpotential of 400mV in comparison with the bare Cys-AuNp-GW composite electrode. This modified electrode exhibited a well resolved pair of redox peaks corresponding to the hexacyanoferrate (II/III) reactions of CuHCF film at a formal potential of 0.65 V at a scan rate of 20 mV s(-1). Electrochemical impedance spectroscopy (EIS) studies with the modified electrode showed a very low charge transfer resistance to the electron transfer kinetics of Fe(II)/Fe(III) reactions. A linear range of 8.5×10(-7) M to 1.2×10(-4) M with a detection limit of 1.85×10(-8) M was achieved for the determination of L-Trp with a sensitivity of 0.1198 μA/μM. The influence of ultrasonication on the stability of the CuHCF film modified electrode was investigated. In addition, the CuHCF film modified electrode displayed an excellent reproducibility towards the real time analysis of L-Trp in commercial milk samples.

Amperometric determination of l-dopa by nickel hexacyanoferrate film modified gold nanoparticle graphite composite electrode

Surface modification of graphite electrode with nickel hexacyanoferrate (NiHCF) film through 2-mercaptoethylamine (MEA) capped gold nanoparticle (GNP) was achieved by a novel fabrication approach. The NiHCF modified electrode exhibits a distinct pair of redox peaks corresponding to anodic and cathodic reactions of hexacyanoferrate (II/III) of NiHCF with a formal potential of 0.33 V versus SCE. l-Dopa, is a potential chemotherapeutic drug used for the treatment of a neurodegenerative disease like Parkinson's disease (PD). l-Dopa was successfully determined by NiHCF modified electrode in the concentration range of 0.82 μM to 2.5 mM with a good sensitivity of 0.363 μA/μM. A reduction in overpotential of 200 mV with a detection limit of 0.53 μM was obtained. Determination of l-dopa in commercial tablets was also investigated by the proposed sensor.

Studies on the Electrocatalytic Reduction of Hydrogen Peroxide on a Glassy Carbon Electrode Modified With a Ruthenium Oxide Hexacyanoferrate Film

Studies on the Electrocatalytic Reduction of Hydrogen Peroxide on a Glassy Carbon Electrode Modified With a Ruthenium Oxide Hexacyanoferrate Film

A selective sensor based on a glassy carbon electrode modified with carbon nanotubes and ruthenium oxide/hexacyanoferrate film for simultaneous determination of ascorbic acid, epinephrine and uric acid

The development of a highly selective sensor for voltammetric determination of ascorbic acid (AA), epinephrine (EP) and uric acid (UA) in the same solution has been achieved by a glassy carbon electrode modified with multi-walled carbon nanotubes and ruthenium oxide hexacyanoferrate film. The modified electrode showed effective catalytic activity toward the electro-oxidation of AA, EP and UA by separating their oxidation peak potentials and producing larger anodic peak currents than those at unmodified electrodes. The electron transfer efficiency and rate constant of the oxidation process were studied using electrochemical impedance spectroscopy. The electro-catalytic peak currents of differential pulse voltammograms increased linearly with AA, EP and UA concentrations in the ranges of 0.2–15.0 μM, 0.1–10.0 μM and 0.90–250 μM with a detection limit of 0.087, 0.052 and 0.599 μM, respectively. The modified electrode showed good sensitivity, selectivity and stability for the voltammetric determination of these important biological compounds. The modified electrode was satisfactorily used for simultaneous determination of AA, EP and UA in pharmaceutical and biological samples.

Electrochemical behaviour of metal hexacyanoferrate converted to metal hydroxide films immobilized on indium tin oxide electrodes—Catalytic ability towards alcohol oxidation in alkaline medium

In this work, we demonstrate a simple method to modify indium tin oxide (ITO) electrodes in order to perform electro-catalytic oxidation of alcohols in alkaline medium. Metal hexacyanoferrate (MHCF) films such as nickel hexacyanoferrate (NiHCF) and copper hexacyanoferrate (CuHCF) were successfully immobilized on ITO electrodes using an electrochemical method. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were employed to characterize the structural and morphological aspects of MHCF films. Cyclic voltammetry (CV) was used to study the redox properties and to determine the surface coverage of these films on ITO electrodes. Electrochemical potential cycling was carried out in alkaline medium in order to alter the chemical structure of these films and convert to their corresponding metal hydroxide films. SEM and XPS were performed to analyze the structure and morphology of metal hydroxide modified electrodes. Electro-catalytic oxidation ability of these films towards methanol and ethanol in alkaline medium was investigated using CV. From these studies we found that metal hydroxide modified electrodes show a better catalytic performance and good stability for methanol oxidation along with the alleviation of CO poisoning effect. We have obtained an anodic oxidation current density of ∼82 mA cm −2 for methanol oxidation, which is at least 10 fold higher than that of any metal hydroxide modified electrodes reported till date. The onset potential for methanol oxidation is lowered by ∼200 mV compared to other chemically modified electrodes reported. A plausible mechanism was proposed for the alcohol oxidation based on the redox properties of these modified electrodes. The methodology adapted in this work does not contain costlier noble metals like platinum and ruthenium and is economically viable.

Metal Hexacyanoferrate with Conducting Polymer Composite Film Modification Electrodes for Selectively Determination of AA, DA and UA

This present work describes oxidation of ascorbic acid (AA) at poly(3,4-ethylenedioxy-thiophene) (PEDOT)/nickel hexacyano-ferrate (NiHCF), PEDOT/copper hexacyanoferrate (CuHCF) and manganese hexacyanoferrate (MnHCF) film were modified on glassy carbon electrode (GCE). The NiHCF-PEDOT, CuHCF-PEDOT and MnHCF-PEDOT hybrid materials are characterized using scanning electron microscope (SEM) techniques. The advantages of these films are demonstrated for selectivity detection of ascorbic acid using cyclic voltammetry and amperometric method. Interestingly, the PEDOT-NiHCF and PEDOT-CuHCF modified electrode exhibited a wide linear response range (from 5 x 10-6~3 x 10-4 M, R2 = 0.9973 and 1.8 x 10-3~1.8 x 10-2 M, R2 = 0.9924). The electrochemical sensors facilitated the oxidation of AA but not responded to other electroactive biomolecules such as dopamine, uric acid, H2O2, glucose. The difference is MnHCF-PEDOT/GCE that no response to AA. In addition, the NiHCF-PEDOT and CuHCF-PEDOT modified electrodes exhibited a distinct advantage of simple preparation, specificity, stability and reproducibility.

Study of zinc hexacyanoferrate—modified platinum electrodes using electrochemical quartz crystal microbalance

In this work, the electrochemical quartz crystal microbalance has been employed to monitor directly the in situ growth of the zinc hexacyanoferrate film during the electrodeposition. Mass changes of the platinum|crystal working electrode were correlated with cyclic voltammetry data. Effects of the sorption of counter-cations (K+, Na+, and $$ {\hbox{NH}}_4^{+} $$ and anions (Cl− and $$ {\hbox{SO}}_4^{2 - } $$ ) during redox reactions were studied. The electrocatalytic oxidation properties of procaine by the zinc hexacyanoferrate films were performed.

Chromium hexacyanoferrate as a cathode material in microbial fuel cells

In this work, it has been demonstrated that the disadvantages associated with the use of the potassium ferricyanide solution as the catholyte in a microbial fuel cell (MFC) were overcome by using a graphite cathode electrochemically modified with chromium hexacyanoferrate (CrHCF) film. The existing use of potassium ferricyanide solution as the catholyte is limited by the need to replace the catholyte every week and it cannot be used in a sustained manner. The present work evaluates the suitability of the CrHCF modified film as a suitable cathode material in a prototype of a MFC wherein Hansenula anomala is used as the biocatalyst in the anode compartment. The CrHCF film was prepared in the presence of the dopant camphor sulphonic acid to improve the reversibility of the film in phosphate buffer.