Platinum Electrode In Alkaline Solution Research Articles

FTIR Characterization of Surface Interactions of Cyanide and Copper Cyanide with a Platinum Electrode in Alkaline Solution

In this paper, the nature of the species formed in theelectrochemical interactions between a polycrystalline platinum surface and cyanide and copper−cyanide species in alkaline solution (pH 13) has been investigated by combining cyclic voltammetry with in situ FTIR spectroscopy. This study was performed because electrochemical reactors for the treatment of cyanide-containing industrial wastewaters have been shown to achieve viable destruction rates when copper ions are present in the alkaline solution through the formation of copper oxide films [Palmer, S. A. K.; Breton, M. A.; Nunno, T. J.; Sullivan, D. M.; Surprenant, N. F.Metal/Cyanide Containing Wastes; Noyes Data Corp.: Park Ridge, New Jersey, 1988. Monteagudo, J. M.; Rodríguez, L.; Villaseñor, J.Advanced oxidation processes for destruction of cyanide from thermoelectric power station waste waters. J. Chem. Technol. Biotechnol. 2004, 79, 117−125. Sax, N. I., Ed.Dangerous Properties of Industrial Materials, 5th ed.; Van Nostrand-Reinhold: New York, 1979; p 526]. It has been found that the complexation of cyanide ions by copper species hinders the adsorption of the anion at the electrode, thus avoiding the characteristic electrode poisoning by CO that occurs in the absence of soluble copper species. Conversely, soluble copper−cyanide complexes can be electrooxidized at the platinum surface through the formation of cyanate species as an intermediate, and of HCOO− and NO as end products. The addition of copper species to the electrolyte also facilitates this route for cyanide oxidation to occur at higher rates without poisoning the platinum electrode.

Electrooxidation of amino acids on platinum electrodes in alkaline solutions

Electrooxidation of amino acids on platinum electrodes in alkaline solutions

Electrocatalytic oxidation of hydrazine on platinum electrodes in alkaline solutions

The mechanism and structure sensitivity of the electrocatalytic oxidation of hydrazine on platinum in alkaline solutions were investigated using cyclic voltammetry, steady-state current measurements, and on-line electrochemical mass spectrometry. The voltammetry of hydrazine oxidation on platinum in alkaline media is characterized by a single diffusion-controlled wave. The on-line electrochemical mass spectrometry measurements of hydrazine oxidation on Pt(1 1 1), Pt(1 0 0), and Pt(1 1 0) surfaces indicated the formation of molecular nitrogen. No oxygen-containing nitrogen compounds were detected under the given experimental conditions. A comparative analysis of voltammetric data for hydrazine oxidation in alkaline solutions on the three surfaces at low overpotentials points to a structure sensitivity of the reaction. The electrocatalytic activity of basal planes increases in the order Pt(1 1 0) > Pt(1 0 0) > Pt(1 1 1), as deduced from the onset of the oxidation wave. The structure of the electrocatalyst surface affects the mechanism of the reaction, although without affecting the selectivity. At low overpotentials the hydrazine oxidation on the Pt(1 1 0) and Pt(1 1 1) surfaces is limited by the rate of electrochemical steps, whereas on Pt(1 0 0) a chemical step that probably involves N 2H 2 adsorbed intermediate is the rate-determining step. Platinum is more active in hydrazine oxidation in alkaline solution than in acidic solutions. In contrast to hydrazine oxidation on platinum in acidic media, the stabilization of chemisorbed hydrazine does not occur to a significant extent in alkaline media.

Kinetics and mechanism of oxygen reduction at hydrous oxide film-covered platinum electrode in alkaline solution

This study uses rotating ring-disk electrode (RRDE) and linear sweep voltammetry (LSV) to characterize oxygen reduction kinetics in alkaline solution on platinum electrodes with various thickness of hydrous oxide (oxyhydroxy) film. Oxyhydroxy films are created on Pt electrodes by pretreatment in 1.0 mol dm −3 KOH at a constant voltage. The pretreatment voltage ranges from −1.2 to 1.0 V and is increased stepwise before each new experimental run to produce seven discreet films. LSV plots show oxyhydroxy film thickness strongly inhibits oxygen reduction and is inversely proportional to RRDE oxygen reduction current I D for LSV voltages E D from −0.1 to −0.46 V, but this trend reverses at E D more negative than −0.46 V so that the worst-performing electrode becomes the best. However, this improvement disappears at around −0.8 V, suggesting this change involves a negatively charged ion, possibly embedded into the metal in the top few atomic layers either interstitially or substitutionally. The 1.0 V-pretreated electrode in the E D range from −0.46 to −0.9 V of highest oxygen reduction current also exhibits the lowest hydrogen peroxide production, with zero H 2O 2 produced at −0.6 V, indicating the brief presence of the oxyhydroxy film on the Pt surface has strong lingering effects. The post-oxyhydroxy Pt surface is very different than the native Pt for oxygen reduction pathway and efficiency. Reaction order with respect to oxygen is close to 1. The rate constants of the direct O 2 to H 2O electroreduction reaction are increased with decreasing the potential from −0.2 to −0.6 V, but the O 2 to H 2O 2 electroreduction is contrary to this expectation. The rate constants of H 2O 2 decomposition on the oxyhydroxy film-covered Pt electrode are near constant around 1 × 10 −4 cm s −1 at E D > −0.5 V.

Electrochamical oxidation of ethanol on Pt-CeO 2/C catalysts

CeO 2/C used in this study was prepared by a solid-state reaction under the microwave irradiation. The activities of Pt/C, Pt/-CeO 2/C for electrochemical oxidation of ethanol were studied in 1.0 M KOH solution by cyclic voltammetry, chronopotentiometry and electrochemical impedance spectroscopy (EIS). The results showed that the composite of Pt-CeO 2/C gave the better performance than Pt/C. The influence of the amount of the addition of CeO 2 on the catalytic activity of alcohols oxidation on platinum electrode in alkaline solution was tested. The electrode with the weight ratio of Pt to CeO 2 of 2:1 with a platinum loading of 0.30 mg cm −2 showed the highest electro-catalytic activity.

Methanol oxidation at platinum electrodes in alkaline solution: comparison between supported catalysts and model systems

Methanol oxidation was studied in 0.1 M NaOH at supported Pt electrodes, and compared with the single crystal Pt electrodes, Pt(1 1 1), Pt(1 1 0) and Pt(3 3 2), chosen as model systems, and with a polycrystalline Pt electrode. The supported Pt electrodes were obtained by chemical (Pt–C/GC) and electrochemical (Pt/GC) deposition of the catalyst layer on glassy carbon resulting in the same metal loading of 20 μg Pt cm −2. Using STM in air, the average particle size distributions, 3–6 nm at Pt–C/GC and 4–32 nm at Pt/GC were determined. Both supported Pt catalysts were less active than polycrystalline Pt. Negligible differences in the kinetics observed between Pt–C/GC and Pt(1 1 0) and also Pt/GC and Pt(1 1 1) suggested that the activities of supported Pt electrodes could be correlated with the activities of single crystal Pt electrodes oriented as the sites dominating in the Pt particles in catalyst deposits. The electrocatalytic activities of the electrodes studied increase in the sequence: Pt(3 3 2) > polycrystalline Pt > Pt–C/GC ∼ Pt(1 1 0) > Pt/GC ∼ Pt(1 1 1). On the basis of diagnostic criteria obtained, the chemical reaction between HCO ad and OH ad giving formate was proposed as the rate limiting step in methanol oxidation.

Kinetics and mechanism of the oxidation of sodium dithionite at a platinum electrode in alkaline solution

In this paper the oxidation of sodium dithionite in alkaline solution was studied by cyclic voltammetry at a stationary and rotating platinum disk electrode. The reaction proceeds in two steps, with sulfite as a relatively stable intermediate and sulfate as final product. It was possible to quantitatively analyze the kinetics of the oxidation wave making use of the experimental evidence that the reaction rate is not dependent on pH, with a reaction order of 0.5 with respect to sodium dithionite and a charge transfer coefficient of 0.5. The proposed mechanism of the overall electron transfer reaction consists of five consecutive steps starting with the adsorption of dithionite, followed by decomposition into SO 2 −, which releases an electron in the rate determining step and finally two more chemical steps leading to the formation of sulfite. The predicted behavior by this mechanism is in agreement with the experimentally observed one.

A new method to analyze polarization curves — its application for the determination of kinetic parameters for oxygen reduction

A new method has been developed to analyze current–potential curves. The treatment was applied to determine the kinetic parameters of oxygen reduction. The reduction of oxygen was studied on thin-film platinum electrodes in alkaline solution. For the purpose of comparison the kinetic parameters were determined by the traditional method of constructing Tafel plots.

Oxidation of glucose at electrodeposited platinum electrodes in alkaline solution

Download options Please wait... Article information DOI https://doi.org/10.1039/FT9938900385 Article type Paper Download Citation J. Chem. Soc., Faraday Trans., 1993,89, 385-389 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions Oxidation of glucose at electrodeposited platinum electrodes in alkaline solution C. P. Wilde and M. Zhang, J. Chem. Soc., Faraday Trans., 1993, 89, 385 DOI: 10.1039/FT9938900385 To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Search articles by author C. Paul Wilde Meijie Zhang

Structural effects in electrocatalysis: Oxidation of D-glucose on single crystal platinum electrodes in alkaline solution

Electrochemical oxidation of D-glucose has been studied in 0.1 M NaOH on single crystal platinum electrodes with thirteen different orientations. The reaction rate depends strongly on the crystallographic orientation of the electrode surface. For most of the surfaces investigated, three voltammetric peaks were observed in the potential region of hydrogen adsorption, the double layer region and the region of anodic film formation. The most active surface is Pt(111). The poisoning adsorbates seem to be less strongly adsorbed on this plane than on Pt(100) or Pt(110). The (100) and (111) oriented steps cause a decrease of the activity of Pt(111). A strongly bound species appears to be adsorbed preferentially on the step sites. Its oxidation was found to coincide with the Pt(OH) ads layer formation.

Oxygen Evolution at Platinum Electrodes in Alkaline Solutions: I . Dependence on Solution pH and Oxide Film Thickness

The oxygen evolution reaction (OER) at platinum electrodes in alkaline solutions of various pH's is reexamined. The existence of two linear regions is confirmed, each having a different dependence on Pt oxide film thickness and the OH− concentration. At low current densities (c.d.) , and, at high c.d., it is 120 mV/decade. While the rate of the OER is independent of the oxide film thickness at the electrodes at low c.d., it is strongly dependent on the film thickness at high c.d., as shown by the large decrease of the rates at a given potential with increasing film thickness. At low c.d., the reaction order with respect to OH− is two, while, at high c.d., the order is . The fractional reaction order at high c.d., is unusual and cannot be accounted for by any standard mechanism proposed in the literature for the OER. These results show that the mechanism of the OER at platinum in alkaline solutions is complex and still not thoroughly understood.

Voltammetric response of iron hydroxide layers precipitated on platinum electrodes in alkaline solution

Voltammograms of thin and thick iron hydroxide layers chemically precipitated on platinum were obtained. The influence of the precipitation conditions of iron hydroxide was studied. Different types of combined potential/time perturbation programmes were employed to correlate the anodic and cathodic voltammetric peaks and to detect possible ageing-like effects. The electrochemical response of the iron hydroxide layer depends considerably on the layer thickness and precipitation conditions. The voltammetric behaviour of the precipitated iron hydroxide layer is interpreted in terms of the complex structure involving an inner poorly hydrated layer and an outer porous layer recently proposed from in situ ellipsometry data.

Pulsed amperometric detection of sulfur compounds: Part I. Initial studies of platinum electrodes in alkaline solutions

Conventional voltammetric and amperometric techniques at Pt or Au electrodes have not been considered applicable for quantitative detection of most sulfur compounds. This is the result of the observed loss of electrode activity caused by accumulation of sulfurous adsorbates and surface oxides. Pulsed Amperometric Detection (PAD) at Pt and Au is highly sensitive for the anodic detection of sulfur compounds, organic and inorganic, which adsorb on the electrode surface. The detection of thiourea by PAD at Pt is described here, and is concluded to correspond to the surface-oxide catalyzed oxidation of the sulfur moiety of adsorbed thiourea to sulfate. Results reported here for detection in a flow-injection system (FI/PAD) produce linear calibration plots of I p vs. c b at low concentration and linear plots of 1/ I p vs 1/ c b at high concentrations. The detection limit for thiourea is 0.38 ppm (i.e., ca 17 ng/45 μl sample) for the FI system used.

Oxygen Evolution at Platinum Electrodes in Alkaline Solutions: II . Mechanism of the Reaction

Kinetic data of the oxygen evolution reaction at Pt electrodes in alkaline solutions have shown two types of behavior, a Tafel slope of 60 mV/decade of current density at low applied current densities and a slope of 120 mV/decade at high current densities. At low current densities, and rate of the reaction was found to be independent of the thickness of the underlying Pt oxide film, while the electrode potential has a −120 mV dependence on solution pH. At high current densities, the rate is strongly dependent on film thickness and exhibits a −180 mV dependence on pH. A mechanism of the oxygen evolution reaction which is consistent with this data is presented. It involves a rate‐determining first electron transfer step at high current densities. At low current densities, the chemical step following the now rapid first electron transfer step is rate limiting. The −180 mV pH dependence observed at high current densities implies a fractional reaction order of with respect to the OH− ion. This has been explained in terms of a dual barrier model of the metal oxide film/solution interface. According to this model, the rates across each barrier are pH dependent. The fractional reaction order is due to the existence of these two dependences and is primarily related to the dependence of the potential difference across the outer Helmholtz layer on pH.

ChemInform Abstract: ANODIC OXIDATION MECHANISM OF HYPOCHLORITE ION ON PLATINUM ELECTRODE IN ALKALINE SOLUTION

Chemischer InformationsdienstVolume 16, Issue 49 Physical Inorganic Chemistry ChemInform Abstract: ANODIC OXIDATION MECHANISM OF HYPOCHLORITE ION ON PLATINUM ELECTRODE IN ALKALINE SOLUTION A. TASAKA, A. TASAKASearch for more papers by this authorT. TOJO, T. TOJOSearch for more papers by this author A. TASAKA, A. TASAKASearch for more papers by this authorT. TOJO, T. TOJOSearch for more papers by this author First published: December 10, 1985 https://doi.org/10.1002/chin.198549022Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume16, Issue49December 10, 1985 RelatedInformation

Anodic Oxidation Mechanism of Hypochlorite Ion on Platinum Electrode in Alkaline Solution

The anodic oxidation of hypochlorite ion (ClO−) or chlorite ion on platinum (Pt) electrode was carried out at 30°C in solution. A plateau was observed on the anodic polarization curve of ClO− in the potential range of 0.90–1.20V and, in the case of , a plateau was observed in the potential range of 1.10–1.50V. When alkaline solutions with various concentration ratios of to were electrolyzed at 1.20V over 50h, the Raman intensity ratio of to ClO− in the anolyte was found to be constant at a value of ca. 0.12 in every case. From the calibration curves obtained in system, the concentration ratio of to ClO− was estimated to be ca. 0.08, which is in good agreement with the theoretical value according to a first‐order consecutive reaction. Based on these results, it is suggested that the mechanism of the anodic oxidation of ClO− is .

XPS investigation of surface oxidation layers on a platinum electrode in alkaline solution

A thick oxidation layer on a platinum electrode has been grown in 1 N NaOH at 3 V vs Ag/AgCl reference electrode. After transferring the Pt electrode into an ultrahigh vacuum chamber the surface layer was analysed by X-ray photoelectron spectroscopy. Pt4f 5/2 amd O1s electron binding energies of 74.3, 77.6 and 530.9 eV respectively, as well as the broad peak shape of the O1s signal and the oxygen-to-platinum intensity ratio of 3.08 point towards a platinum—oxyhydroxide PtO(OH) 2. This formula is in good agreement with cyclic voltammetry curves, measured for the same electrode, that revealed two cathodic reduction peaks for oxygen surface coverages equivalent to more than two hydrogen monolayers. These two peaks were assigned to PtOH and PtO. XPS analysis at elevated temperatures showed that the thick (5 nm) oxidation layer decomposes at 400 K to a mixture of several oxides and hydroxides of Pt 4+ and Pt 2+ and Pt metal with a ratio of O-to-Pt of 1. This mixture further gradually decomposes to only a monolayer of oxygen at 770–870 K. Sodium cations were found to be present in trace amounts in the adlayer and to strongly shift the O1s binding energy to lower values.

Amperometric detection of simple carbohydrates at platinum electrodes in alkaline solutions by application of a triple-pulse potential waveform

The response of ten simple carbohydrates was investigated voltammetrically at platinum electrodes in 0.10 M sodium hydroxide by application of a conventional linear sweep waveform and a triple-pulse waveform. Linear-sweep data were interpreted to suggest that electrochemical reactions of the carbohydrates involve oxidation of adsorbed hydrogen atoms produced by surface-catalyzed dehydrogenation of the adsorbed carbohydrate. The triple-pulse measurement technique was evaluated for a flow-injection system by introducing 100-μl samples into a stream of 0.1 M NaOH with a flow rate of 0.375 ml min -1, and measuring the peak current. Peak currents for ten carbohydrates at 0.5 mM ranged from 17 to 42 μa and a detection limit of 0.01 mM was evaluated for dextrose. Calibration plots of reciprocal peak current ( I -1 p) vs. reciprocal of concentration (C -1) were linear for dextrose and sorbitol concentrations between 0.1 and 1.0 mM.

Behaviour of nitrate impurity in nickelcadmium cells

The oxidation-reduction behaviour of NO3−, NO2−, N2O22−, NH2OH and NH3 at a platinum electrode in alkaline solution has been investigated using cyclic voltammetry. The results have been compared with the corresponding behaviour of these species at charged, porous cadmium and nickel hydroxide electrodes in order to understand the likely behaviour of NO3− impurities in nickelcadmium cells. The reactions are shown to be irreversible processes and strongly dependent on the nature of the electrode surfaces. The reactions which are likely to be involved in a charged cell can be represented by the overall scheme: $${\text{NO}}_{\text{3}} ^\_ {\text{NO}}_{\text{2}} ^\_ {\text{NH}}_{\text{3}} \xrightarrow{{{\text{slow}}}}{\text{N}}_2 $$ It is suggested that the self-discharge of cells containing NO3− is limited by slow kinetic effects rather than by diffusion as previously supposed.

Mechanism of the electrooxidation of methanol on a smooth platinum electrode in alkaline solution

1. The proposed mechanism of the electrooxidation of methanol on a platinum electrode explains the formation of various chemisorbed particles and various products of electrooxidation in alkaline and acid solutions under stationary conditions. 2. In alkaline solution, in contrast to acid solution, a process of catalytic decomposition of methanol, parallel to the electrooxidation of chemisorbed particles, takes place on a platinum electrode at high concentrations of methanol and at low anodic potentials. 3. The apparent activation energy of the electrooxidation of methanol in alkaline solutions is lower than in acid solutions at the same p'otentials.