Activation Of Glassy Carbon Electrodes Research Articles

The Effect of Electrochemical Ageing of Glassy Carbon Electrodes on VII-VIII and VIV-VV Kinetics

Electrode activity towards the negative and positive half-cell reactions of a vanadium flow battery were investigated. Cyclic voltammetry and electrochemical impedance spectroscopy were employed to monitor electrode activity of glassy carbon electrodes towards VII-VIII and VIV-VV redox reactions during electrochemical ageing through repeated anodic and cathodic treatments. Electrode activity is found to increase with number of treatment steps, showing little difference initially between anodised and cathodised electrodes. However, after several treatments, a potential-differentiated behaviour emerges, with distinct enhanced and inhibited states. For VII-VIII, anodised electrodes showed enhanced activity, while cathodised electrodes were inhibited. Conversely, for VIV-VV, cathodised electrodes had enhanced activity. In almost all cases, the activity is greater than that of an untreated electrode. Eventually, electrode activities stabilise in a steady-state region where activity depends on the final treatment potential rather than the number of steps. In this region, activity can be toggled reproducibly between enhanced and inhibited states. Therefore, it can be concluded that functional groups, rather than surface roughening or defect formation, are responsible for this toggling capability. Furthermore, for VIV-VV, steady-state activity levels and the number of treatment steps required to reach this region are found to be dependent on the upper and lower treatment potentials.

Electrochemically nitric acid pre-treated glassy carbon electrode sensor for catechol and hydroquinone: A voltammetric study

The electrochemical pre-treatment method was applied for the activation of glassy carbon electrode for the detection of catechol (CC) and hydroquinone (HQ) by using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The influence of concentration, pH and scan rate was studied at nitric acid pre-treated glassy carbon electrode (NAPGCE) for both CC and HQ. The NAPGCE depicts the adsorption controlled process and it exhibits a good limit of detection for CC and HQ was found at 0.99 and 1.2 μM respectively. The suggested electrode exhibited good sensitivity and reliability in the simultaneous electroanalysis of CC and HQ. Moreover, the recovery of CC and HQ was developed by a simple method in tap water.

Titania, zirconia and hafnia supported ruthenium(0) nanoparticles: Highly active hydrogen evolution catalysts

Designing a cost-effective catalyst with high activity and stability for hydrogen evolution reaction (2H+ + 2e− → H2) is a big challenge due to increasing demand for energy. Herein, we report the electrocatalytic activity of glassy carbon electrodes with group 4 metal oxides (TiO2, ZrO2, HfO2) supported ruthenium(0) nanoparticles in hydrogen evolution reaction. Electrochemical activity of modified electrodes is investigated by recording linear sweep voltammograms in 0.5 M H2SO4 solution. The results of electrochemical measurements reveal that among the three electrodes the glassy carbon electrode with Ru0/TiO2 (1.20% wt. Ru) exhibits the highest activity with a relatively small Tafel slope of 52 mV dec−1, the highest exchange current density of 0.728 mA cm−2, and the smallest overpotential of 41 mV at j = 10 mA cm−2. Furthermore, it demonstrates superior stability in acidic solution with an unaltered onset potential for long term electrochemical measurement.

One step synthesis of chlorine-free Pt/Nitrogen-doped graphene composite for oxygen reduction reaction

Chlorine-free Platinum/nitrogen-doped graphene oxygen reduction reaction catalysts were synthesized by a one step method of annealing a mixture of platinum acetylacetonate and graphene oxide under ammonia atmosphere. Nanoparticles with close to the ideal particle size for oxygen reduction reaction (ORR) were formed, i.e., with diameter of 3–4 nm (500 and 600 °C) and 6 nm (700 °C). X-ray photoelectron spectroscopy confirmed the successful introduction of both pyridinic and pyrrolic type nitrogen moieties into the graphene layers, which indicates a strong interaction between the nanoparticles and the graphene layers. The electrocatalytic activity of glassy carbon electrodes (GCE) modified with the synthesized Pt/NG samples for oxygen reduction was compared to that of a platinum/carbon black catalyst modified electrode in acidic and alkaline media. Based on the measured limiting current densities and calculated electron transfer number, the highest activity was measured in acidic and alkaline media on the samples annealed at 600 and 700 °C, respectively.

Electrochemical impedance spectroscopy study on polymerization of L-lysine on electrode surface and its application for immobilization and detection of suspension cells.

Poly-L-lysine (PLL), which has been employed as a conductive polymer in the construction of some electrochemical sensors, can be prepared using L-lysine by cyclic voltammetry (CV) with a wide potential range. However, the presented explanation and description about its polymerization mechanism seems oversimplified because the self-reaction of electrode and the electrolysis of solvent at high potential are ignored. This work presents an intensive investigation on the relevant reactions during the process of PLL-polymerization using CV, X-ray photoelectron spectroscopy, Fourier transform-infrared spectroscopy, and electrochemical impedance spectroscopy. At a higher positive potential, the transfer from lysine molecules to cation radicals and the polymerization reaction on the glassy carbon electrode (GCE) could be achieved, accompanied by the activation of GCE, the formation of oxygen-containing functional groups, and the generation of oxygen derived from the oxidation of water. The adsorbed oxygen had a seriously negative effect on the formation of PLL unless it suffered reduction at a lower negative potential. The charge transfer through the electrochemical polymerized PLL film was seriously hindered by the immobilization of suspension cells due to the electrostatic interaction. The charge-transfer resistance difference (ΔR(ct)) was increased with the enhancement of the cell number (N(cells)) and the 1/ΔR(ct) value displayed a linear response with 1/N(cells) in the range of 5.0 × 10(2)-1.0 × 10(5) cells with a detection limit of 180 cells estimated at a signal-to-noise ratio of 3. A sensitive electrochemical sensor for the quantitative detection of suspension cells was developed.

Voltammetric determination of nicotine in cigarette tobacco at electrochemically activated glassy carbon electrode

The electrochemical behavior of nicotine was investigated using cyclic and square wave voltammetric techniques. Electrochemical activation of glassy carbon electrode significantly increased the oxidation peak current of nicotine compared to the bare glassy carbon. At the activated glassy carbon electrode, the square wave voltammetry of nicotine revealed an oxidation peak at +838 mV ( vs. SCE) in phosphate buffer solution of pH 7. Under optimized conditions, the linear range (R 2 = 0.998) and detection limit (3σ) for nicotine determination were found to be 1-200 µM and 0.7 µM, respectively. The method was successfully applied for the determination of nicotine in two brands of commercial cigarettes and acceptable recovery values of 97-108% were found. KEY WORDS : Nicotine, Activated glassy carbon, Square wave voltammetry, Cigarette Bull. Chem. Soc. Ethiop. 2013 , 27(3), 321-328. DOI: http://dx.doi.org/10.4314/bcse.v27i3.1

Activation of glassy carbon electrodes by photocatalytic pretreatment

Abstract This paper describes a simple and rapid photocatalytic pretreatment procedure that removes contaminants from glassy carbon (GC) surfaces. The effectiveness of TiO2 mediated photocatalytic pretreatment procedure was compared to commonly used alumina polishing procedure. Cyclic voltammetric and chronocoulometric measurements were carried out to assess the changes in electrode reactivity by using four redox systems. Electrochemical measurements obtained on photocatalytically treated GC electrodes showed a more active surface relative to polished GC. In cyclic voltammograms of epinephrine, Fe(CN)63−/4− and ferrocene redox systems, higher oxidation and reduction currents were observed. The heterogeneous electron transfer rate constants (ko) were calculated for Fe(CN)63−/4− and ferrocene which were greater for photocatalytic pretreatment. Chronocoulometry was performed in order to find the amount of adsorbed methylene blue onto the electrode and was calculated as 0.34 pmol cm−2 for photocatalytically pretreated GC. The proposed photocatalytic GC electrode cleansing and activating pretreatment procedure was more effective than classical alumina polishing.

Mechanism of activation of glassy carbon electrodes by cathodic pretreatment

The performance of carbon electrodes depends on the surface pretreatment methods. An exclusively cathodically pretreated glassy carbon electrode (GCE) shows very good activity towards monomeric molybdate(VI) ion adsorption and its reduction. X-ray photoelectron spectroscopy studies reveal the creation of >C–O– surface groups on cathodisation. A strong interaction between the Mo(VI) ion and these >C–O– surface groups with the formation of Mo(V) is responsible for the activation of the cathodically pretreated GCE surface.

Effects of ultrasound on the electrodeposition of lead dioxide on glassy carbon electrodes

The electrodeposition of lead dioxide from lead(II) nitrate in an acid medium has been used as a test reaction to study the effects of an ultrasound field. The different behaviours found between platinum and glassy carbon electrodes have been compared by means of cyclic voltammetry and simple potential steps. The current–time response for a platinum electrode is not affected by the presence or absence of ultrasound; in contrast, significant changes have been observed in the characteristic regions of these curves (induction time t0) with the glassy carbon electrode. Scanning electron microscopy (SEM) has been employed to follow changes in the surface topography after the electrodes had been exposed to ultrasound. Results indicate that neither pits nor structural modifications that may increase the electrode surface occur with the device used. It is concluded that the activation of glassy carbon electrodes by the action of an ultrasound field for electrodeposition of lead dioxide is associated with the surface functionalization caused by the reaction of OH radicals (derived from aqueous sonolysis) with the carbon surface.

Unusual activation of glassy carbon electrodes for enhanced adsorption of monomeric molybdate(VI)

Abstract We have found that an exclusively cathodically pretreated glassy carbon electrode, which has been hitherto considered ineffective in many redox systems, is highly activated towards monomeric Mo(VI) adsorption and its reduction. The most commonly used anodic pretreatment produces an inactive GCE surface with poor response. X-ray photoelectron spectroscopy has been used to probe the surface concentration change of O- and C-containing species with the pretreatment, and identify the nature of the molybdate species adsorbed on the pretreated GCE surfaces. The results obtained clearly show that the precathodisation produces > CO-surface groups, and that there is a correlation between the saturation surface coverage of Mo(VI) determined by cyclic voltammetry experiments and the alcohol O/total O ratio of the pretreated electrodes calculated from XPS measurements. The unusual activation by precathodisation is explained by a mixed potential mechanism .

Influence of the supporting electrolyte and the pH on the electrooxidative activation of glassy carbon electrodes

Glassy carbon electrodes were modified by electrooxidative pretreatment in sulphate, phosphate, perchlorate and tetrafluoroborate solutions applying a constant potential (1600 mV vs. Ag/AgCl) for 1 h. In addition, the pH of the sulphate and phosphate solutions was altered, and two cations (Li + and Na +) were used as counterions of tetrafluoroborate. The effect of the different supporting electrolytes and the pH during electrochemical pretreatment on the formation of graphite oxide on the glassy carbon surfaces was investigated. All anodizations resulted in higher background currents, increased reversibility of the catechol couple, and decreased values of the anodic peak potentials of catechol and ascorbic acid. The anodic peak heights of catechol were dependent on the anion and the pH chosen for the anodization, and the anodic peak heights of ascorbic acid seemed to be specific for the anion chosen as the supporting electrolyte. Most of the modified electrodes showed coloured surface layers and increased wettability. The biggest influence on the anodization had LiClO 4 as supporting electrolyte. The change of the cation from Na + to Li + and the counterion of BF 4 − had almost no effect on the results of the electrochemical pretreatment.

Activation of glassy carbon electrode in aqueous and non-aqueous media

By recording the cyclic voltammograms at a freshly polished and electrochemically pretreated ( ex situ) Tokai gce for the ferric/ferrous reaction in water, water + DMF, and water + ethanol, it was established that the activating effect of electrochemical pretreatment decreases with increasing content of the organic solvent in the solution.

Effects of wavelength, pulse duration and power density on laser activation of glassy carbon electrodes

The hypothesis that laser activation of glassy carbon (GC) electrodes is thermally driven was investigated by comparing simulated surface temperatures for several lasers and experimental conditions. Assuming no phase changes, the surface temperature vs. time profile for a laser pulse striking a GC electrode was predicted by finite difference simulation. It was predicted that peak surface temperature depends on power density, wavelength, pulse duration and the optical properties of the carbon. Experimentally, laser activation is weakly wavelength dependent for ascorbic acid and Fe 2+ 3+ . The surface temperatures required for activation were consistent for different lasers, supporting the conclusion that laser activation is thermally driven. Furthermore, predicted surface temperatures during activation were below the melting point of carbon but well above the boiling point of water. The results should be useful for predicting the effectiveness of different laser conditions on electron transfer activation.

Activation of Glassy Carbon Electrodes by Polishing with Ceramics Particles

Abstract Glassy carbon electrode polished with ceramics particles (TiB2, SiC, and TiC) showed higher oxidation rate of ascorbic acid. The activation seems to depend on hardness of glassy carbon and ceramics particles and to be influenced by fresh edges formed on glassy carbon surface.

Voltammetric studies on glassy carbon electrodes I: Electrochemical behaviour of glassy carbon electrodes in H 2SO 4, Na 2SO 4 and NaOH media

Voltammetric investigations were carried out on glassy carbon electrodes in 0.5 M H 2SO 4, 0.5 M Na 2SO 4 and 1.0 M NaOH over a wide potential region from -2.5 V to +2.0 V versus a saturated calomel electrode at sweep rates up to 640 m V s -1. The results indicate three different processes. (1) In the middle of the potential region reversible surface redox processes take place. Fresh oxidation of surface carbon probably does not occur in this region. (2) In the anodic region surface oxidation as well as oxygen evolution reactions take place. This surface oxidation is probably linked with the activation of glassy carbon electrodes and hence is considered in some detail. (3) In extreme cathodic regions hydrogen adsorption takes place. The surface functional groups undergo spontaneous phase changes in both the middle and the anodic potential regions. The nature of the processes are probably controlled by pH. Preliminary studies in NaCl also indicate a substantial anion effect especially in the anodic region. A detailed discussion of glassy carbon surface behaviour is given with due consideration of earlier work in this field.

Vacuum heat-treatment for activation of glassy carbon electrodes

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTVacuum heat-treatment for activation of glassy carbon electrodesDan T. Fagan, Ing Feng. Hu, and Theodore. KuwanaCite this: Anal. Chem. 1985, 57, 14, 2759–2763Publication Date (Print):December 1, 1985Publication History Published online1 May 2002Published inissue 1 December 1985https://doi.org/10.1021/ac00291a006RIGHTS & PERMISSIONSArticle Views1093Altmetric-Citations240LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (617 KB) Get e-Alerts Get e-Alerts

Activation and deactivation of glassy carbon electrodes

A procedure is described for treating glassy carbon to create an active electrode. For the first time, a level of activity comparable to that of active Pt has been attained. This was determined by the heterogeneous electron transfer rate (0.14±0.01 cm/s) of ferri-/ferro-cyanide. The possible factors in the activation of the glassy carbon electrode (GCE), such as electrode surface cleanliness, roughness and functional groups were studied. However, the GCE was found to deactivate with time; the rate of this deactivation appeared to correlate with the loss rate of hydrogen adsorption/desorption sites at Pt. These results suggest that impurity adsorption played an important role in the deactivation. In addition to assessing the level of activity via the ferri-/ferro-cyanide redox probe, the monitoring of electroactive surface functionalities by differential pulse voltammetry is proposed as a diagnostic for the validation of electrode preparation steps.

Activation of glassy carbon electrodes by alternating current electrochemical treatment

Glassy carbon electrodes subjected to “severe” electrochemical treatment is saturated chloride solutions exhibit enhanced electrochemical reversibility compared to untreated electrodes. Apparently faster rates of electron-transfer result in lowering of the overpotential by 110–300 mV for eight electroactive species tested. Systematic alterations in the response in terms of peak potential, sensitivity, background current, and stability are reported. Scanning electron micrographs show the introduction of pits of random size distribution. From the practical point of view, the most significant improvement is observed in differential pulse measurements, that are highly sensitive to small changes in the rate of electron transfer. In amperometric detection for liquid chromatography, the pretreated electrodes are shown to facilitate the quantitation of different eluting species. It appears that the surface and bulk properties of the glassy carbon have profound effects on the observed behavior.

Activation of Glassy Carbon Electrodes by Dispersed Metal Oxide Particles: I . Ascorbic Acid Oxidation

Various metal oxides (MOx) were dispersed onto a glassy carbon (GC) surface for the purpose of catalyzing the oxidation of ascorbic acid . Of the 37 different metal oxides examined, more than 20 showed varying degrees of rate enhancement (henceforth referred to as activation) for oxidation. The highest degree of activation was exhibited by those MOx's whose oxidation state of the metal was +3 or higher, such as zirconium oxide, ceric oxide, cobaltic oxide, chromic oxide, stannic oxide, and the previously reported alumina. The double layer capacitance was also observed to increase with MOx/GC's compared to the bare GC electrode. This increase suggested that the surface area of the GC electrodes increased due to the dispersion of MOx. The pH dependence of the activation at MOx/GC was considerably different from that at a bare GC electrode and suggested that the enhancement mechanism may involve an acceleration of a proton‐transfer step via interaction with the MOx/GC surface. A model of the physical structure of the MOx/GC surface is proposed to account for the carbon surface activation.