Electrocatalytic reduction of hydrogen peroxide at Prussian blue modified electrodes: a RDE study

Electrocatalytic reduction of hydrogen peroxide at Prussian blue modified electrode has been studied with rotating disk electrode in pH 5.5 and 7.3 solutions. It has been shown that the electrocatalytic cathodic reduction obeys Koutecky–Levich relationship at electrode potentials ranging from 0.1 to −0.4 V vs. Ag/AgCl for low concentrations of peroxide not exceeding 0.3 mM. Within this potential window, the calculated kinetic cathodic current ranges within the limits of 2.15–6.09 and 1.00–3.60 mA cm⁻² mM⁻¹ for pH 5.5 and 7.3, respectively. For pH 5.5 and 7.3 solutions, a linear slope of the dependence of kinetic current on electrode potential of −10.8 and −2.89 mA cm⁻² mM⁻¹ V⁻¹, respectively, has been obtained. At a higher concentration of peroxide, exceeding 0.6 mM, deviations from Koutecky–Levich relationship have been observed. These deviations appear more expressed at higher potentials and higher solution pH. The results obtained have been interpreted within the frame of two-step reaction mechanism, including (1) dissociative adsorption of hydrogen peroxide with the formation of OH radicals and (2) one-electron reduction of these radicals to OH⁻ anions. At a higher concentration of peroxide, and especially at a higher pH, the second process becomes rate limiting.     

Rotating disk electrode study of electrocatalytic oxidation of ascorbate at Prussian blue modified electrode

Electrooxidation of ascorbate has been studied with the use of a rotating disk electrode. The results obtained show an efficient electrocatalytic oxidation of ascorbate at the Prussian blue (PB) modified electrode to proceed in solutions of pH 5.5 and 7.3. Depending on solution pH, the onset potential for ascorbate electrooxidation at PB modified electrode appears shifted by 0.1–0.2 V to lower values, as compared to an unmodified glassy carbon electrode. Within the electrode potential window of 0.3 to 0.5 V vs. Ag/AgCl, and electrode rotation velocity of 50–2000 rpm, the catalytic current obeys Koutecky-Levich equation at a submillimolar ascorbate concentration. Kinetic current densities, obtained from the data treatment, are higher for a pH 5.5 solution, and also at higher electrode potential.      

Sensor for traces of hydrogen peroxide using an electrode modified by multiwalled carbon nanotubes, a gold-chitosan colloid, and Prussian blue

An electrochemical sensor for trace levels of hydrogen peroxide (HP) was fabricated by the self-assembly of multi-walled carbon nanotubes, a gold-chitosan colloid, followed by electrodeposition of Prussian blue. The electrode was characterized by cyclic voltammetry, electrochemical impedance spectroscopy and other methods. The electrode shows well-defined peaks at 101 mV and 193 mV, the reduction current is linearly related to the concentration of HP in the range from 4.0 to and 19.6 μM. The detection limit of 3.36 μM (at an S/N of 3).     

A sensitivity-controlled hydrogen peroxide sensor based on self-assembled Prussian Blue modified electrode

In this communication, a hydrogen peroxide (H₂O₂) sensor based on self-assembled Prussian Blue (PB) modified electrode was reported. Thin film of PB was deposited on the electrode by self-assembly process including multiple sequential adsorption of ferric ions and hexacyanoferrate ions. The as-prepared PB modified electrode displayed sufficient stability for practical sensing application. At an applied potential of ?0.05 V vs. Ag/AgCl (sat. KCl), PB modified electrode with 30 layers exhibited a linear dependence on H₂O₂ concentration in the range of 1 × 10^?6–4 × 10^?4 M (r = 0.9998) with a sensitivity of 625 mA M^?1 cm^?2. It was found that the sensitivity of H₂O₂ sensors could be well controlled by adjusting the number of deposition cycles for PB preparation. This work demonstrates the feasibility of self-assembled PB modified electrode in sensing application, and provides an effective approach to control the sensitivity of PB-based amperometric biosensors.     

Oxidation pathways and kinetics of morphine in acidic and neutral media on the aluminum electrode covered by metallic palladium and modified by Prussian blue

This paper describes the use of an aluminum electrode covered by metallic palladium and modified by Prussian blue prepared by a simple and rapid electroless method for the electro-oxidation of morphine. Two different pathways for electro-oxidation of morphine at various pH ranges were suggested. Also, some thermodynamic and kinetic parameters such as the number of electrons involved in the rate determining step, n _α , transfer coefficient α, and the total electrons (n) involved in morphine oxidation at the time scale of the cyclic voltammetric technique, the catalytic rate constant of the electrochemical process k, and diffusion coefficient of morphine D were determined. The mean values obtained are 0.5, 0.5, 1, 26.8 M^-1 s^-1 and 3.1 × 10⁻⁵ cm² s⁻¹, respectively.     

Palladized aluminum electrode covered by Prussian blue film as an effective transducer for electrocatalytic oxidation and hydrodynamic amperometry of N-acetyl-cysteine and glutathione

The mediated oxidation of N-acetyl cysteine (NAC) and glutathione (GL) at the palladized aluminum electrode modified by Prussian blue film (PB/Pd–Al) is described. The catalytic activity of PB/Pd–Al was explored in terms of Fe^III[Fe^III(CN)₆]/Fe^III[Fe^II(CN)₆]¹⁻ system by taking advantage of the metallic palladium layer inserted between PB film and Al, as an electron-transfer bridge. The best mediated oxidation of NAC and GL on the PB/Pd–Al electrode was achieved in 0.5 M KNO₃ + 0.2 M potassium acetate of pH 2. The mechanism and kinetics of the catalytic oxidation reactions of the both compounds were monitored by cyclic voltammetry and chronoamperometry. The charge transfer-rate limiting step as well as overall oxidation reaction of NAC or GL is found to be a one-electron abstraction. The values of transfer coefficients α, catalytic rate constant k and diffusion coefficient D are 0.5, 3.2 × 10² M⁻¹ s⁻¹ and 2.45 × 10⁻⁵ cm² s⁻¹ for NAC and 0.5, 2.1 × 10² M⁻¹ s⁻¹ and 3.7 × 10⁻⁵ cm² s⁻¹ for GL, respectively. The modifying layers on the Pd–Al substrate have reproducible behavior and a high level of stability in the electrolyte solutions. The modified electrode is exploited for hydrodynamic amperometry of NAC and GL. The amperometric calibration graph is linear in concentration ranges 2 × 10⁻⁶–40 × 10⁻⁶ for NAC and 5 × 10⁻⁷–18 × 10⁻⁶ M for GL and the detection limits are 5.4 × 10⁻⁷ and 4.6 × 10⁻⁷ M, respectively.     

Amperometric biosensor for hydrogen peroxide based on the co-electrodeposition of horseradish peroxidase and methylene blue on an ITO electrode modified with an anodic aluminum oxide template

We report on a nano-array sensor for hydrogen peroxide (H₂O₂) that is based on a nanoporous anodic aluminum oxide template. This was used as a matrix for the co-immobilization of horseradish peroxidase (HRP) and methylene blue (MB) on the surface of an indium tin oxide electrode. The immobilized HRP retained its natural activity and MB is capable of efficiently shuttle electrons between HRP and the electrode. The new electrode was characterized by SEM and electrochemical methods. It exhibits fast response, long-term stability, high sensitivity and good selectivity to H₂O₂. Under optimized conditions, it linearly responds to H₂O₂ in the concentration range from 1.0?μM to 26?mM, with a detection limit of 0.21?μM (at S/N?=?3).

A hydrogen peroxide biosensor based on multiwalled carbon nanotubes-polyvinyl butyral film modified electrode

A novel approach to construct a amperometric biosensor for determination of H₂O₂ is described. Horseradish peroxidase (HRP) as a base enzyme was immobilized into the mixture of multiwalled carbon nanotubes (MWNTs) and polyvinyl butyral (PVB). Taking the classical hydroquinone as mediator, cyclic voltammetry and amperometric measurements were used to study and optimize the performance of the resulting H₂O₂ biosensor. The effect of the concentration of MWNTs, HRP, hydroquinone, solution pH, and the working potential of amperometry on the electrochemical biosensor was systematically studied. The results showed that the fabricated biosensor demonstrated significant electrocatalytic activity for the reduction of hydrogen peroxide with wide linear range from 0.000832 to 0.6 mM, and low detection limit 0.000167 mM (S/N = 3) with fast response time less than 8 s. The apparent Michaelis–Menten constant was determined to be 0.049 mM. Additionally, the biosensor exhibited high sensitivity, rapid response and good long-term stability.     

铁氰化铈薄膜固载血红蛋白修饰的过氧化氢生物传感器的制备及性能

采用电化学沉积法将铁氰化铈(CeHCF)薄膜修饰于玻碳电极(GCE)表面,得到铁氰化铈薄膜修饰玻碳电极;将血红蛋白(Hb)固载于该修饰电极表面,成功制得了Hb/CeHCF/GCE过氧化氢生物传感器.考察了铁氰化铈薄膜修饰玻碳电极的氧化还原机理和制备条件,并对血红蛋白在电极上的电子传递过程进行了较为深入的研究.结果表明,铁氰化铈薄膜为血红蛋白提供了温和的固载环境,可实现血红蛋白与电极表面的直接电子转移,提高了血红蛋白的电化学活性;所制得的传感器对过氧化氢具有较高的催化响应和较强的稳定性.相关研究结果在生物医学和临床医学领域具有一定的借鉴意义.     

Label-free amperometric immunobiosensor based on a gold colloid and Prussian blue nanocomposite film modified carbon ionic liquid electrode

A novel experimental methodology based on a Prussian blue (PB) and gold nanoparticles (AuNPs) modified carbon ionic liquid electrode (CILE) was developed for use in a label-free amperometric immunosensor for the sensitive detection of human immunoglobulin G (HIgG) as a model protein. The CILE was fabricated by using the ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate as binder. Controllable electrodeposition of PB on the surface of the CILE and coating with 3-aminopropyl triethylene silane (APS) formed a film with high electronic catalytic activity and large surface area for the assembly of AuNPs and further immobilization of HIgG antibody. The electrochemistry of the formed nanocomposite biofilm was investigated by electrochemical techniques including cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy. The HIgG concentration was measured through the decrease of amperometric responses in the corresponding specific binding of antigen and antibody. The decreased differential pulse voltammetric values were proportional to the HIgG concentration in two ranges, 0.05–1.25 ng mL⁻¹ and 1.25–40 ng mL⁻¹, with a detection limit of 0.001 ng mL⁻¹ (S/N = 3). This electrochemical immunoassay combined the specificity of the immunological reaction with the sensitivity of the AuNPs, ionic liquid, and PB amplified electrochemical detection and would therefore be valuable for clinical immunoassays.     

Self-assembling of Prussian blue nanocubic particles on nanoporous glassy carbon and its use in the electrocatalytic reduction of hydrogen peroxide

In this paper, self-assembled Prussian blue nanocubic particles on nanoporous glassy carbon was developed. The morphology of the PBNP-modified porous glassy carbon was characterized by scanning electron microscopy. The PBNP-GCE-red film-modified electrode was used for the sensitive detection of hydrogen peroxide. The electrochemical behavior of the resulting sensor was investigated using cyclic voltammetry and chronoamperometry. The value of α, k _cat, and D was calculated as 0.35, 1.7 × 10⁵ cm³ mol^?1 s^?1, and 2.6 × 10^?5 cm² s^?1, respectively. The calibration curve for hydrogen peroxide determination was linear over 0–600 μM with a detection limit (S/N = 3) of 0.51 μM.     

Electrochemical behavior of hydrogen peroxide sensor based on new methylene blue as mediator

A novel amperometric hydrogen peroxide sensor was proposed by co-immobilizing new methylene blue (NMB) and Horseradish peroxidase (HRP) on glassy carbon electrode through covalent binding. The electrochemical behavior of the sensor was studied extensively in 0.1 mol/L phosphate buffering solution (pH = 7.0). The experiments showed NMB could effectively transfer electrons between hydrogen peroxide and glassy carbon electrode. The electron transfer coefficient and apparent reaction rate constant were determined to be 0.861 and 1.27 s⁻¹. The kinetic characteristics and responses of sensor on H₂O₂ were investigated. The Michaelis constant is 8.27 mol/L and the linear dependence of current on H₂O₂ is in the range of 2.5–100 μmol/L. At the same time, the effects of solution pH, buffer capacity, and temperature on the sensor were examined. Translated from Chemistry, 2006, 23(8): 916–920 [译自: 化学通报]     

Electrochemical reduction of oxygen to hydrogen peroxide in a gas-diffusion electrode based on mesoporous carbon

Mesoporous carbon prepared by template synthesis using SBA-15 mesostructured silicate material was tested as an electrocatalyst for electrochemical synthesis of Н₂О₂ from О₂ in a two-layer gas-diffusion electrode. Preparative syntheses of Н₂О₂ in 0.06 to 2.0 M aqueous solutions of various electrolytes (pH 2–8) were performed at current densities in the interval 0.05–0.19 A cm^–2. Solutions with an Н₂О₂ concentration of 1–2.8 M were prepared with 46–70% current efficiency. Thus, the material tested shows promise as an electrocatalyst of two-electron reduction of oxygen to Н₂О₂.     

基于聚苯胺-普鲁士蓝/普鲁士蓝复合膜的过氧化氢电化学传感器的制备及表征

利用聚苯胺和普鲁士蓝的协同作用,构建了聚苯胺-普鲁士蓝/普鲁士蓝复合膜的H2O2电化学传感器.聚苯胺的带正电骨架和带负电的普鲁士蓝粒子相互吸引,且聚苯胺提供了很多氧化还原位点,有利于普鲁士蓝粒子的进一步均匀生长,使制备的传感器具备优异的电催化性能.采用扫描电镜和电化学方法对修饰电极进行了表征.在最佳实验条件下,该修饰电...     

Simplifying the evaluation of graphene modified electrode performance using rotating disk electrode voltammetry

Graphene modified electrodes have been fabricated by electrodeposition from an aqueous graphene oxide solution onto conducting Pt, Au, glassy carbon, and indium tin dioxide substrates. Detailed investigations of the electrochemistry of the [Ru(NH(3))(6)](3+/2+) and [Fe(CN)(6)](3-/4-) and hydroquinone and uric acid oxidation processes have been undertaken at glassy carbon and graphene modified glassy carbon electrodes using transient cyclic voltammetry at a stationary electrode and near steady-state voltammetry at a rotating disk electrode. Comparisons of the data with simulation suggest that the transient voltammetric characteristics at graphene modified electrodes contain a significant contribution from thin layer and surface confined processes. Consequently, interpretations based solely on mass transport by semi-infinite linear diffusion may result in incorrect conclusions on the activity of the graphene modified electrode. In contrast, steady-state voltammetry at a rotating disk electrode affords a much simpler method for the evaluation of the performance of graphene modified electrode since the relative importance of the thin layer and surface confined processes are substantially diminished and mass transport is dominated by convection. Application of the rotated electrode approach with carbon nanotube modified electrodes also should lead to simplification of data analysis in this environment.     

Electrochemical deposition and mechanism investigation of Prussian blue on graphic carbon paste electrode from an acidic ferricyanide solution

Prussian blue (PB) films were electrochemically deposited on graphite carbon paste electrodes (GCPEs) from an acidic solution of ferricyanide using the potentiodynamic and potentiostatic techniques. Interestingly, we, for the first time, observed that on the surface of GCPE, the electrochemistry of PB films strongly depended on the deposition potential. A maximum formation rate of PB was obtained at a more positive deposition potential (0.4 V vs saturated calomel electrode) on GCPE than that on Au or Pt electrode. The ratio of peak current at ca 0.75 V to the one at 0.19 V varied with the deposition potential. In addition, the electrocatalytic activity of the modified GCPEs towards the reduction of hydrogen peroxide considerably changed with the formation potentials of the PB films. These phenomena can be due to the different formation mechanism of PB at different deposition potentials. Dedicated to Prof. Dr. Teresa Iwasita on the occasion of her 65th birthday in recognition of her numerous contributions to interfacial electrochemistry.     

Efficient nonenzymatic hydrogen peroxide sensor in acidic media based on Prussian blue nanoparticles-modified poly(o-phenylenediamine)/glassy carbon electrode

The Prussian blue nanoparticles(PBNPs) were prepared by a self-assembly process, on a glassy carbon(GC) electrode modified with a poly(o-phenylenediamine)(Po PD) film. The stepwise fabrication process of PBNPs-modified Po PD/GCE was characterized by scanning electron microscopy(SEM) and electrochemical impedance spectroscopy. The prepared PBNPs showed an average size of 70 nm and a homogeneous distribution on the surface of modified electrodes. The PBNPs/Po PD/GCE showed adequate mechanical, electrochemical stability and good sensitivity in comparison with other PB based H_2O_2 sensors. The present modified electrode exhibited a linear response for H_2O_2 reduction over the concentration range of 1–58.22 mmol L ~(-1)with a detection limit of ca. 0.8 mmol L ~(-1)(S/N = 3), and sensitivity of 3187.89 m A(mol L ~(-1)) ~(-1)cm 2using the amperometric method. This sensor was employed for the H_2O_2 determination in real sample and also exhibited good interference resistance and selectivity.     

尿酸在聚亚甲基蓝修饰金电极上的电化学及电化学动力学性质

尿酸(Uric acid,UA)是人体内嘌呤核苷酸分解代谢过程中的最终产物.体液中尿酸的含量变化可以充分反映出人体新陈代谢、免疫等机能状况,同时也可间接反映出与嘌呤代谢的有关疾病[1].