Modified Nickel Electrode Research Articles

Amperometric Highly Sensitive Phosphate Ion Sensor Based on the Electrochemically Modified Ni Electrode.

We present a study of high-performance electrochemical phosphate sensors, which are exquisitely designed and easy to operate. We innovatively utilized the insolubility of nickel phosphate and developed a new type of sensor through electrochemical methods. The experiment first used cyclic voltammetry to determine -0.4 V as the optimal electrochemical modification potential and used constant potential electrodeposition technology to form a nickel oxide layer on the surface of the nickel electrode, which serves as the active layer in response to phosphate ions. The changes in the surface structure and chemical composition of the electrode before and after modification were thoroughly characterized by scanning electron microscopy and energy scattering spectroscopy analysis. The performance evaluation of the sensor shows that the modified nickel electrode has excellent responsiveness to phosphate ions in the concentration range of 10-7 to 10-10 mol/L, with a detection lower limit of 10-10 mol/L. As the concentration decreases, a shoulder peak appears at ∼0.63 V and the current change shows a regular increase. Compared with traditional detection methods, this sensor exhibits higher stability and practicality and is suitable for the rapid identification of phosphates in real samples. In summary, this study successfully developed a fast, sensitive, and wide response range current type electrochemical phosphate sensor, which has broad application prospects in environmental monitoring, water quality analysis, and biomedical fields.

Preliminary study of electrochemical conversion of glucose on novel modified nickel electrodes

Preliminary study of electrochemical conversion of glucose on novel modified nickel electrodes

A potentiometric phosphate ion sensor based on electrochemically modified nickel electrode

The effective detection of phosphate ions is very important in the fields of chemistry, biology, medicine, environment and industry. At present, the detection of phosphate ion mainly depends on molybdenum blue colorimetry. Although this method is accurate, it needs sample pretreatment, complex operation and high cost. Therefore, it is urgent to design and develop a phosphate ion sensor with high efficiency, accuracy, simple operation and real-time on-line detection. In this study, a phosphate ion sensor was designed and developed by electrochemical modification based on nickel metal electrode. Nickel electrode was specifically modified to form a phosphate of Ni on the surface of Ni electrode. The phosphate ion response of Ni-PME(Nickel-phosphate modified electrode) was evaluated in a two-electrode system. The results show that under the condition of pH 4, Ni-PME can respond to phosphate ions with a concentration of 10−5 M to 0.1 M, the response slope is −81.0 mV dec−1, and the selectivity coefficients for common anions are below −2. The response time is less than 20 s. The stability of electrode potential is very high, and the fluctuation of 24-hour continuous test potential is within ± 3 mV. The lifetime is more than 4 weeks. Compared with the traditional molybdenum blue colorimetry, Ni-PME showed good accuracy and good recovery rate.

Anodic Oxidation of Sulphite in Alkaline Media on Platinum Nanoparticles Modified Nickel Electrode

Anodic Oxidation of Sulphite in Alkaline Media on Platinum Nanoparticles Modified Nickel Electrode

Ruthenium oxide modified nickel electrode for ascorbic acid detection

Electrodes of ruthenium oxide modified nickel were prepared by a thermal decomposition method. The stoichiometry of the modifier, RuOx, was quantitatively determined to be a meta-stable phase, RuO5. The electrodes were employed to sense ascorbic acid in alkaline solution with a high sensitivity, 296 μAcm−2 mM−1, and good selectivity for eight kinds of disturbing reagents. We found that the ascorbic acid was oxidized irreversibly in solution. To match with the variation of the morphology, the sensitivity reached a maximum when the RuOx segregated with a nano-crystalline feature. We find that the substrate oxidized as the deposited RuOx grew thicker. The feature of the deposited RuOx changed from nano-particles to small islands resulting from the wetting effect of the substrate oxide, NiO; meanwhile the sensitivity decreased dramatically. The endurance of the RuOx/Ni electrode also showed a good performance after 38 days of successive test.

Electrochemical investigation of the voltammetric determination of hydrochlorothiazide using a nickel hydroxide modified nickel electrode.

The preparation and electrochemical characterization of a nickel hydroxide modified nickel electrode as well as its behavior as electrocatalyst toward the oxidation of hydrochlorothiazide (HCTZ) were investigated. The electrochemical behavior of the modified electrode and the electrooxidation of HCTZ were explored using cyclic voltammetry. The voltammetric response of the modified electrode in the detection of HCTZ is based on the electrochemical oxidation of the Ni(II)/Ni(III) and a chemical redox process. The analytical parameters for the electrooxidation of HCTZ by the nickel hydroxide modified nickel electrode were obtained in NaOH solution, in which the linear voltammetric response was in the concentration range from 1.39×10(-5) to 1.67×10(-4)mol L(-1) with a limit of detection of 7.92×10(-6)mol L(-1) and a sensitivity of 0.138 μA Lmmol(-1). Tafel analysis was used to elucidate the kinetics and mechanism of HCTZ oxidation by the modified electrode.

Plastic supported platinum modified nickel electrode and its high electrocatalytic activity for sodium borohydride electrooxidation

A novel plastic/multi-walled carbon nanotube (MWNTs)-nickel (Ni)-platinum (Pt) electrode (PMNP) is prepared by chemical-reducing Pt onto the surface of Ni film covered plastic/MWNTs (PM) substrate. The MWNTs are adhered by a piece of commercial double faced adhesive tape on the surface of plastic paper and the Ni film is prepared by a simple electrodeposition method. The morphology and phase structure of the PMNP electrode are characterized by scanning electron microscopy, transmission electron microscope and X-ray diffractometer. The catalytic activity of the PMNP electrode for NaBH4 electrooxidation is investigated by means of cyclic voltammetry and chronoamperometry. The catalyst combines tightly with the plastic paper and exhibits a good stability. MWNTs serve as both conductive material and hydrogen storage material and the Ni film and Pt are employed as electrochemical catalysts. The PMNP electrode exhibits a high electrocatalytic performance and the oxidation current density reaches to 10.76 A/(mg·cm) in 0.1 mol/dm3 NaBH4 at 0 V, which is much higher than those in the previous reports. The using of waste plastic reduces the discarding of white pollution and consumption of metal resources.

Fabrication of nickel nanoparticles modified electrode by reverse microemulsion method and its application in electrolytic oxidation of ethanol

This paper highlights recent work on formulation and stability of nickel sulphate W/O microemulsion using hydrophilic nonionic surfactant Tween 80, and its use for electrodeposition of uniform Ni-nanoparticles on nickel plating. The prepared microemulsion was found to be crystal clear and very stable for more than 30 days at a wide range of temperature (20≥T≤45°C). The Tween 80/n-hexane/n-hexanol/water microemulsion was used for fabrication of nickel nanoparticles modified nickel electrode. These electrodeposited Ni-nanoparticles were characterized by SEM, which revealed that uniform spherical nanoparticles of diameter 100–160nm were deposited on electrode surface. The Ni-nanoelectrode was applied for electrooxidation of alcohols. The catalytic efficiency of Ni-nanoelectrode was far better than bulk electrode due to its high surface area.

Redox Switching and Oxygen Evolution at Hydrous Oxyhydroxide Modified Nickel Electrodes in Aqueous Alkaline Solution: Effect of Hydrous Oxide Thickness and Base Concentration

Redox Switching and Oxygen Evolution at Hydrous Oxyhydroxide Modified Nickel Electrodes in Aqueous Alkaline Solution: Effect of Hydrous Oxide Thickness and Base Concentration

Electro-catalytic oxidation of methane at multi-walled carbon nanotubes-Nafion/nickel hydroxide modified nickel electrode

A novel chemical modified nickel (Ni) electrode based on multi-walled carbon nanotubes (MWCNTs), Nafion film and nickel hydroxide has been successfully fabricated for methane (CH 4) detection at ambient conditions. The morphology of the MWCNTs–Nafion/Ni(OH) 2 film was characterized by transmission electron microscopy and the electrochemical properties of the Ni modified electrode were studied by cyclic voltammetry. The MWCNTs–Nafion/Ni(OH) 2–Ni electrode showed good catalytic effect on the oxidation of CH 4 in 1.0 M NaOH. In addition, the modified electrode was free from nitrogen and oxygen interferences. When differential pulse voltammetry was applied to the MWCNTs–Nafion/Ni(OH) 2–Ni electrode, a good linear relationship between the oxidation peak current ( i) and CH 4 concentration ( C methane) was obtained: i = 1.841 C methane + 46.25, where i is in μA and C methane is in 0.0–16.0% (v/v). The relative standard deviation for detection of 3.0% (v/v) CH 4 was 1.80% ( n = 5). The proposed Ni modified electrode is anticipated to provide a promising technique to detect CH 4 at ambient conditions.

Voltammetric Study and Detection of Methane on Nickel Hydroxide–Modified Nickel Electrode

The nickel hydroxide–modified nickel (NMN) electrode was prepared by cyclic voltammetry. The modified electrode exhibited better catalytic effect toward electrochemical oxidation of methane in 1.0 mol · L−1 NaOH solution. The catalytic activation of nickel hydroxide on the nickel electrode surface was investigated in different supporting electrolyte solutions by the cyclic voltammetry method in detail, and the related electrochemical oxidation of methane at the NMN electrode was first proposed by amperometric i‐t curve method under the experiment conditions. The results indicated that in the 1.0 mol · L−1 NaOH solution, the anodic peak current increased with the increased concentration of methane.

A novel titanium-supported nickel electrocatalyst for cyclohexanol oxidation in alkaline solutions

Abstract A novel titanium-supported nickel electrode (Ni/Ti) is fabricated by a simple hydrothermal process using hydrazine hydrate as a reduction agent. Its electrocatalytic activity towards cyclohexanol oxidation has been investigated by cyclic voltammetry (CV), chronoamperometry (CA), quasi-steady state polarization and electrochemical impedance spectroscopy (EIS). Effects of various parameters such as potential scan rate and cyclohexanol concentration on the electro-oxidation of cyclohexanol are investigated. Results show that the Ni/Ti electrode behaves as an efficient catalyst for the electro-oxidation of cyclohexanol in basic media and its electrocatalytic activity towards cyclohexanol oxidation is higher than a nickel oxyhydroxide modified nickel electrode (NOMN). It is confirmed that during the anodic potential sweep the electro-oxidation of cyclohexanol follows the formation of NiOOH on the electrode surface and is then catalysed by NiOOH. The rate-determining step for cyclohexanol oxidation is the reaction between the high oxidation state nickel (Ni 3+ ) and the adsorbed cyclohexanol on the surface of the Ni/Ti.

Oxygen electroreduction on anthraquinone-modified nickel electrodes in alkaline solution

The electrochemical reduction of oxygen has been studied on anthraquinone (AQ) modified nickel electrodes in 0.1 M KOH solution using the rotating disk electrode (RDE) technique. Modification of the Ni electrode surface with AQ by electrochemical reduction of the corresponding diazonium salt was carried out in two different media (in acetonitrile and in aqueous acidic solution). The AQ-modified Ni electrodes showed a good electrocatalytic activity for O 2 reduction. The RDE data indicate that the reduction of oxygen on Ni/AQ electrodes proceeds by a two-electron pathway in alkaline solution. The O 2 reduction results obtained for Ni/AQ electrodes are compared with those of AQ-modified glassy carbon electrodes.

Electrocatalytic oxidation of cyclohexanol on a nickel oxyhydroxide modified nickel electrode in alkaline solutions

Electrocatalytic oxidation of cyclohexanol was investigated with cyclic voltammograms, linear galvanic voltammograms and chronoamperometric responses on a nickel oxyhydroxide modified nickel (NOMN) electrode prepared by cycling the potential of a nickel electrode in the potential range of 0.1 V to 0.6 V (vs SCE) in alkaline solutions. It was found that cyclohexanol was oxidized by NiOOH generated with further electrochemical oxidation of nickel hydroxide during the anodic potential sweep. One of the products of the reaction between cyclohexanol and NiOOH was Ni(OH) 2 which was subsequently oxidized to NiOOH on the anode. This resulted in the appearance of a new anodic peak in cyclic voltammograms compared with the absence of cyclohexanol and this anodic peak strongly depends upon potential scan rates and cyclohexanol concentrations. In addition, the presence of cyclohexanol in NaOH solutions also lead to the decrease of anodic potentials in linear galvanic voltammetric responses and the increase of current densities in chronoamperometric curves. Results showed that the oxidation of cyclohexanol on the NOMN electrode follows the catalytic reaction mechanism.

Methanol electrooxidation on a nickel electrode modified by nickel–dimethylglyoxime complex formed by electrochemical synthesis

Abstract Nickel–dimethylglyoxime complex (NiDMG) modified nickel electrode (Ni/NiDMG) showed a catalytic activity towards methanol oxidation in NaOH solution. The modified electrode prepared by the dimethylglyoxime anodic deposition on Ni electrode in the solution containing 0.20 mol L−1 NH4Cl + NH4OH (pH 9.50) and 1.0 × 10−4 mol L−1 dimethylglyoxime. The modified electrode conditioned by potential recycling in a potential range of 100–700 mV (vs. SCE) by cyclic voltammetry in alkaline medium (0.10 M NaOH). The results show that the NiODMG film on the electrode behaves as an efficient catalyst for the electrooxidation of methanol in alkaline medium via Ni(III) species formed on the electrode with the cross exchange reaction occurring throughout the film at a low concentration of methanol. A plausible mechanism was proposed for catalytic oxidation of methanol at NiODMG-modified Ni electrode. Moreover, the effects of various parameters such as anodic deposition time, anodic deposition potential (both in modification step), potential scan rates, methanol concentration and media temperature on the electrooxidation of methanol were investigated.

The structure, morphology and electrochemical impedance study of the hydrogen evolution reaction on the modified nickel electrodes

Composite layers of modified amorphous nickel were prepared by simultaneous electrodeposition of Ni and TiO 2 on a Cu substrate from a solution containing TiO 2 (anatase) particles suspended by stirring. Scanning electron microscopy, X-ray diffractometry, Auger spectroscopy and absorption spectroscopy, were used for physical and chemical characterization of the layers. Obtained deposits exhibit an amorphous structure of the Ni-P matrix in which the crystalline component, TiO 2, is embedded. Additionally, the presence of non-stoichiometric oxide, Ti 2O 3, formed on a boundary of the TiO 2 grain and nickel matrix in consequence of the reduction conditions during the electrodeposition, was revealed by auger electron spectroscopy (AES). The hydrogen evolution reaction (HER) was investigated on the Ni-P+TiO 2 and compared with Ni-P electrode in 5 M KOH at 25°C using steady-state polarization and electrochemical impedance spectroscopy (EIS). In order to explain the electrochemical behaviour of the electrode materials, electrical equivalent circuits containing: (i) the constant-phase element (CPE), (ii) the porous electrode impedance, and (iii) two-CPE elements were compared and verified. The ac impedance behaviour of the electrodes may be well described using the two-CPE or porous electrode model in case of the Ni-P+TiO 2, and a simple CPE model for the Ni-P. The results obtained from the EIS and steady-state measurements allowed for the determination of the mechanism and kinetics of the HER. It has been found that an increase in electrochemical activity of the Ni-P+TiO 2 electrode is due to both the increase in the real surface area and the presence of titanium oxides TiO 2 and Ti 2O 3, as compared with the Ni-P electrode.

Electrocatalytic oxidation of methane at nickel hydroxide modified nickel electrode in alkaline solution

Nickel hydroxide modified nickel electrodes prepared by cycling the potential of a nickel electrode in alkaline solution exhibited electrocatalytic activity for the oxidation of methane in alkaline media. In the presence of methane the oxidation peak current of nickel hydroxide increases while that of the reverse process decreases. This is attributed to the mediation of nickel species, probably β-NiOOH phase, in the process of electrocatalysis. The mechanism of methane oxidation has also been discussed in terms of the formations of intermediates normally encountered in small organics electro-oxidation. It has also been suggested that in the further oxidation of the intermediates, ions in the solution or anion vacancies in the solid phase of nickel hydroxide are probably involved.

Electrochemical properties of the pasted nickel electrode using surface modified Ni(OH) 2 powder as active material

Nickel hydroxide powder was modified by immersing the mixture of nickel hydroxide powder with cobalt compounds in an alkali solution or by chemical deposition. Electrochemical properties of the pasted nickel electrodes consisting of surface modified Ni(OH) 2 powder in a porous nickel substrate were studied. The results show that the active material utilization of the modified nickel electrodes greatly increases due to the uniform distribution of a Co(OH) 2 layer on the surface of the nickel hydroxide powder resulting in the improvement of the electrochemical activity and conductivity. The EIS results show that the Co(OH) 2 layer decreases the charge-transfer resistance and increases the active surface area of the nickel electrode.

Surface-modified electrodes for NADH oxidation in oxidoreductase-catalysed synthesis

Three surface-modified electrodes were investigated: 3,4-dihydroxybenzaldehyde electropolymerized on glassy carbon, hexacyanoferrate modified nickel electrodes, Meldola Blue adsorbed on graphite, for application to NADH oxidation in oxidoreductase-catalysed synthesis. The high overpotential, which is generally required for NADH oxidation on clean electrodes, was perfectly overcome with the three electrodes and especially with the Meldola blue modified graphite electrode. This electrode allowed fast NADH oxidation at potentials as low as 0.00 V vs SCE. It also ensured good storage stability. It is stressed that the key problem in applying this electrode to synthesis is the decrease in its electrocatalytic properties under operating synthesis conditions. An operating procedure was established that allowed ageing of the electrode to be directly linked to the current measurement. Following this procedure, several methods were investigated for improving the half-life of the electrode: pulse electrolysis, replacing NADH by NAD+ in the initial solution, lowering the NAD+ concentration and using dextran-bound NAD+. In the best conditions, the half-life reached 152 min instead of 34 min with the initial conditions, proving that fouling by anodically produced NAD+ was first of all identified as a very important cause of electrode ageing. Modification of intrinsic surface properties of the electrode also led to the decrease of the interface efficiency.

Investigation of smooth and modified nickel surface by optoelectrochemical method

Optoelectrochemical method (OEM) as a combination of electrochemical and ellipsometric methods has been developed and used for quantitative approach of generalized description of surface state and electrocatalytic properties of smooth standardized and modified nickel electrodes in alkaline solutions. Two well-known principles are underlined the OEM: (1) insensitivity of ellipsometric method to hydrogen adsorption at least within the wavelengths interval 500–700 nm; (2) proportionality between changes in adsorbed oxygen amount and ellipsometric parameter Δ. Using OEM it has been succeeded to obtain the ‘absolute’ oxygen adsorption isotherm with respect to true surface area. On the base of this ‘absolute’ isotherm the simple method for true surface (roughness, R) determination has been proposed. First for the case of compact nickel the hydrogen adsorption and absorption isotherms and oxygen adsorption one have been obtained separately. By extrapolation of Δ, R dependence to R=1 the metal optic constants n and k has been determined. The blocking behavior of different types of oxides has been investigated. The peculiar properties of amorphous layer produced by abrading treatment have been studied. It has been shown that this amorphous layer adsorbs much more hydrogen amount with respect to true surface area than common one. The specific oxidation rate of hydrogen adsorbed on such a layer is also much higher.