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Derek Pletcher - One of the best experts on this subject based on the ideXlab platform.
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electrodeposited Lead Dioxide coatings
2011Co-Authors: Derek Pletcher, F C WalshAbstract:Lead Dioxide coatings on inert substrates such as titanium and carbon now offer new opportunities for a material known for 150 years. It is now recognised that electrodeposition allows the preparation of stable coatings with different phase structures and a wide range of surface morphologies. In addition, substantial modification to the physical properties and catalytic activities of the coatings are possible through doping and the fabrication of nanostructured deposits or composites. In addition to applications as a cheap anode material in electrochemical technology, Lead Dioxide coatings provide unique possibilities for probing the dependence of catalytic activity on layer composition and structure (critical review, 256 references).
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a novel flow battery a Lead acid battery based on an electrolyte with soluble Lead ii part vii further studies of the Lead Dioxide positive electrode
2009Co-Authors: Derek Pletcher, F C WalshAbstract:The structure of thick Lead Dioxide deposits (approximately 1 mm) formed in conditions likely to be met at the positive electrode during the charge/discharge cycling of a soluble Lead-acid flow battery is examined. Compact and well adherent layers are possible with current densities >100 mA cm−2 in electrolytes containing 0.1–1.5 M Lead(II) and methanesulfonic acid concentrations in the range 0–2.4 M; the solutions also contained 5 mM hexadecyltrimethylammonium cation, C16H33(CH3)3N+. From the viewpoint of the layer properties, the limitation is stress within the deposit Leading to cracking and lifting away from the substrate; the stress appears highest at high acid concentration and high current density. There are, however, other factors limiting the maximum current density for Lead Dioxide deposition, namely oxygen evolution and the overpotential associated with the deposition of Lead Dioxide. A strategy for operating the soluble Lead-acid flow battery is proposed.
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the electrodeposition of highly reflective Lead Dioxide coatings
2009Co-Authors: C T J Low, Derek Pletcher, F C WalshAbstract:Abstract In the presence of a suitable surfactant, such as hexadecyltrimethylammonium chloride or bromide, highly reflective and hard Lead Dioxide coatings with a black appearance can be electrodeposited from methanesulfonic acid media at room temperature (295 K). The reflective PbO 2 coatings are compact, adherent to the (vitreous carbon or carbon-polymer) substrate and can be formed at current densities of 10 to 100 mA cm −2 at a thickness up to several hundred microns. The coatings were characterised by measurement of surface optical reflectance, surface roughness, surface microstructure, phase composition and crystallite size. The reflective PbO 2 films were found to mainly consist of the alpha (orthorhombic) phase with feather-like and orientated microstructures. The crystallite size and surface roughness were in the order of tens of nanometres and their optical reflectance was several orders of magnitude higher than matte coatings produced in the absence of additives.
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a novel flow battery a Lead acid battery based on an electrolyte with soluble Lead ii part vi studies of the Lead Dioxide positive electrode
2008Co-Authors: Derek Pletcher, F C Walsh, Hantao Zhou, Gareth Kear, C John T Low, R G A WillsAbstract:The structure of thick Lead Dioxide deposits (approximately 1 mm) formed in conditions likely to be met at the positive electrode during the charge/discharge cycling of a soluble Lead-acid flow battery is examined. Compact and well adherent layers are possible with current densities >100 mA cm?2 in electrolytes containing 0.1–1.5 M Lead(II) and methanesulfonic acid concentrations in the range 0–2.4 M; the solutions also contained 5 mM hexadecyltrimethylammonium cation, C16H33(CH3)3N+. From the viewpoint of the layer properties, the limitation is stress within the deposit Leading to cracking and lifting away from the substrate; the stress appears highest at high acid concentration and high current density. There are, however, other factors limiting the maximum current density for Lead Dioxide deposition, namely oxygen evolution and the overpotential associated with the deposition of Lead Dioxide. A strategy for operating the soluble Lead-acid flow battery is proposed.
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the fabrication of Lead Dioxide layers on a titanium substrate
2006Co-Authors: Yusairie Mohd, Derek PletcherAbstract:Abstract It is shown that stable and active Lead Dioxide on titanium anodes (including mesh electrodes) may be fabricated by appropriate pretreatment of the substrate and a strategy involving the anodic deposition of two PbO2 layers—a thick underlayer with the Lead Dioxide doped with fluoride and iron and a top layer with the Lead Dioxide doped with bismuth. Periods on open circuit, especially in solutions containing an oxidisable organic or inorganic species must, however, be avoided since all forms of PbO2 are reducible unless protected by an anodic current; the rates of the reduction does depend on the medium, the dopants in the PbO2 and the morphology of the layer. It is also shown that, as at gold substrates, the morphology of the PbO2 layer on titanium (consequently, their properties including adhesion and electrocatalytic activity) depend strongly on the deposition conditions including the bath composition (including Pb(II) concentration, acid concentration, concentration and choice of dopant ion), temperature, current density and deposition charge.
F I Danilov - One of the best experts on this subject based on the ideXlab platform.
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kinetics of Lead Dioxide electrodeposition from nitrate solutions containing colloidal tio2
2009Co-Authors: A B Velichenko, R аmadelli, а V кnysh, т V Lukyanenko, F I DanilovAbstract:Abstract The influence of particles of colloidal titanium Dioxide on Lead Dioxide electrodeposition from nitrate electrolytes was studied in the work. Addition of the nanostructured ТiO2 particles to the electrolyte increases the rate of Lead Dioxide formation. This enhancement is ascribed to extra nucleation sites contributed by Ti–O radicals generated at the TiO2 surface by OH species, in turn formed by discharge of water. A four stages kinetics scheme is proposed for description of the process of Lead Dioxide electrodeposition in presence of oxides of the valve metal in colloidal solutions. It is suggested that the presence of TiO2 nanoparticles influences crystallization, charge transfer and diffusion stages.
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Electrodeposition of Lead Dioxide from methanesulfonate solutions
2009Co-Authors: A B Velichenko, Rossano Amadelli, E.v. Gruzdeva, Tatiana Luk'yanenko, F I DanilovAbstract:Abstract Lead Dioxide electrodeposition from methanesulfonic media and physicochemical properties of the resulting oxide were studied in this work to improve anodic process at PbO 2 /Pb 2+ electrode of flow battery. The presence of methanesulfonate ions in the electrodeposition solution causes only a quantitative difference in the PbO 2 electrodeposition process without apparently changing the reaction mechanism. In methanesulfonic media PbO 2 electrodeposition rate is higher than in nitrate solutions. Current efficiency of PbO 2 formation depends on electrode potential (or deposition current density), electrolyte composition (concentration of Pb 2+ and methanesulfonate ions), hydrodynamic conditions, pH and temperature of the solution. It is important to note that thick PbO 2 coatings (up to 2 mm) with good mechanical properties and adhesion to the substrate can be deposited in a wide range of current density (2–100 mA cm −2 ).
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electrodeposition of co doped Lead Dioxide and its physicochemical properties
2002Co-Authors: A B Velichenko, R Amadelli, Elena A Baranova, D V Girenko, F I DanilovAbstract:Abstract An investigation on the electrodeposition of cobalt-doped Lead Dioxide has been carried out, as part of a study ultimately aimed at producing anodes with improved electrocatalytic activity and stability. An assessment of the influence of different experimental parameters on the amount of incorporated Co was made for PbO 2 films grown either at constant current or constant potential. The Co content in PbO 2 decreases with increasing temperature and pH of the deposition solution, probably due to the fact that increasing the growth electrolyte temperature from 25 to 65 °C causes a decrease of the deposition potential from 1.5 to 1.4 V. Similarly, a rise of the electrolyte pH brings about a decrease of the electrodeposition potential. The same electrodeposition kinetics are obeyed in the absence and in the presence of Co 2+ in solution. In the potential region where the Pb(II) oxidation becomes diffusion controlled, the corresponding limiting current decreases when Co 2+ is present. This is due to an enhancement of the parallel O 2 evolution process. Experiments showed that Co 2+ is weakly adsorbed on PbO 2 , and that the adsorption follows Langmuir conditions. Surface analysis by XRD and XPS of the Co-doped PbO 2 films does not reveal major changes compared to undoped samples. Tritium radiotracer experiments show that the effect of Co-doping on incorporation of protons is appreciable in films deposited at relatively high temperature (65 °C). In this case, as a function of electrodeposition time, the amount of incorporated tritium first increases then decreases to the same value measured for undoped PbO 2 . This behaviour is likely to be due to substitution of Pb(IV) with Co(II) followed by oxidation of the incorporated Co(II) to Co(III) as electrodeposition proceeds.
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oxygen and ozone evolution at fluoride modified Lead Dioxide electrodes
1999Co-Authors: R Amadelli, A B Velichenko, D V Girenko, Lidia Armelao, N V Nikolenko, S V Kovalyov, F I DanilovAbstract:Abstract This work examines the behaviour of fluorine modified β-PbO2 electrodes in the processes of O2 and O3 evolution in sulphuric acid. The electrochemical kinetic analyses of these processes are based on quasi-steady-state polarisation and impedance data. The good agreement between the two sets of measurements allows some basic conclusions to be drawn. In particular, the O2 evolution process is always inhibited at F-doped PbO2 electrodes, and impedance results suggest possible changes in the mechanism, with electrodesorption of intermediates becoming more important as the concentration of the doping element increases. The interpretation of the data for the less positive potentials region invokes the specific adsorption of SO42− as a factor influencing the kinetics of O2 evolution. The current efficiency for O3 formation as a function of the amount of NaF added to the PbO2 growth solution reaches a maximum for a concentration of 0.01 mol dm−3. A plausible cause for the decrease on the higher concentration side is the discharge of adsorbed SO42− (or HSO4−) eventually yielding persulphate. This reaction is known to be favoured in the presence of a relatively high amount of fluoride in the electrolyte. An analysis of the results of modified neglect of diatomic differential overlap (MNDO) calculations on Pb cluster models and of X-ray photoelectron spectroscopy (XPS) data suggests that the coverage by weakly adsorbed oxygen species (OH and H2O) is an important parameter that is influenced by F-doping.
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mechanism of Lead Dioxide electrodeposition
1996Co-Authors: A B Velichenko, D V Girenko, F I DanilovAbstract:Abstract The electrodeposition of PbO 2 from HClO 4 solutions of Pb(II) at an Au rotating ring disk electrode was studied as a function of applied potential and rotational velocity. Experimental data have shown that the process of PbO 2 formation has several stages. The first stage is the formation of oxygen containing particles as OH ads , chemisorbed on the electrode. At the next chemical stage, these particles interact with Lead compounds forming the soluble intermediate product Pb(OH) 2+ which is further oxidized electrochemically to form PbO 2 . Pb(III) intermediate products were detected on a gold ring electrode at more positive potentials.
F C Walsh - One of the best experts on this subject based on the ideXlab platform.
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electrodeposited Lead Dioxide coatings
2011Co-Authors: Derek Pletcher, F C WalshAbstract:Lead Dioxide coatings on inert substrates such as titanium and carbon now offer new opportunities for a material known for 150 years. It is now recognised that electrodeposition allows the preparation of stable coatings with different phase structures and a wide range of surface morphologies. In addition, substantial modification to the physical properties and catalytic activities of the coatings are possible through doping and the fabrication of nanostructured deposits or composites. In addition to applications as a cheap anode material in electrochemical technology, Lead Dioxide coatings provide unique possibilities for probing the dependence of catalytic activity on layer composition and structure (critical review, 256 references).
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electrodeposited nanostructured Lead Dioxide as a thin film electrode for a lightweight Lead acid battery
2011Co-Authors: D R P Egan, C T J Low, F C WalshAbstract:Thin films of nanostructured Lead Dioxide are investigated as a positive electrode material for a lightweight Lead-acid battery. The films are obtained by constant current deposition from electrolytes of Lead methanesulfonate in methanesulfonic acid. The films are tested in two conditions namely (a) cyclic voltammetry and (b) constant current battery cycling in sulfuric acid. The charge and discharge current density, charge density and charge efficiency are measured as a function of cycle number. The effect of deposition conditions, such as solution temperature (295 and 333 K), type of substrate and electrolyte additive (hexadecyltrimethylammonium hydroxide), on the electrochemical performance of the PbO2 in sulfuric acid is investigated. It is found that the as-deposited Lead Dioxide film is compact and nanostructured β-phase structure. Following successive cycling in sulfuric acid, the compact thin film gradually transforms into a porous microstructure consisting of positive active material (PbO2 and PbSO4), several tens of nanometres size. The charge density, discharge density and peak discharge current density of the PbO2 improve with cycling of the thin film electrode.
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a novel flow battery a Lead acid battery based on an electrolyte with soluble Lead ii part vii further studies of the Lead Dioxide positive electrode
2009Co-Authors: Derek Pletcher, F C WalshAbstract:The structure of thick Lead Dioxide deposits (approximately 1 mm) formed in conditions likely to be met at the positive electrode during the charge/discharge cycling of a soluble Lead-acid flow battery is examined. Compact and well adherent layers are possible with current densities >100 mA cm−2 in electrolytes containing 0.1–1.5 M Lead(II) and methanesulfonic acid concentrations in the range 0–2.4 M; the solutions also contained 5 mM hexadecyltrimethylammonium cation, C16H33(CH3)3N+. From the viewpoint of the layer properties, the limitation is stress within the deposit Leading to cracking and lifting away from the substrate; the stress appears highest at high acid concentration and high current density. There are, however, other factors limiting the maximum current density for Lead Dioxide deposition, namely oxygen evolution and the overpotential associated with the deposition of Lead Dioxide. A strategy for operating the soluble Lead-acid flow battery is proposed.
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the electrodeposition of highly reflective Lead Dioxide coatings
2009Co-Authors: C T J Low, Derek Pletcher, F C WalshAbstract:Abstract In the presence of a suitable surfactant, such as hexadecyltrimethylammonium chloride or bromide, highly reflective and hard Lead Dioxide coatings with a black appearance can be electrodeposited from methanesulfonic acid media at room temperature (295 K). The reflective PbO 2 coatings are compact, adherent to the (vitreous carbon or carbon-polymer) substrate and can be formed at current densities of 10 to 100 mA cm −2 at a thickness up to several hundred microns. The coatings were characterised by measurement of surface optical reflectance, surface roughness, surface microstructure, phase composition and crystallite size. The reflective PbO 2 films were found to mainly consist of the alpha (orthorhombic) phase with feather-like and orientated microstructures. The crystallite size and surface roughness were in the order of tens of nanometres and their optical reflectance was several orders of magnitude higher than matte coatings produced in the absence of additives.
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a novel flow battery a Lead acid battery based on an electrolyte with soluble Lead ii part vi studies of the Lead Dioxide positive electrode
2008Co-Authors: Derek Pletcher, F C Walsh, Hantao Zhou, Gareth Kear, C John T Low, R G A WillsAbstract:The structure of thick Lead Dioxide deposits (approximately 1 mm) formed in conditions likely to be met at the positive electrode during the charge/discharge cycling of a soluble Lead-acid flow battery is examined. Compact and well adherent layers are possible with current densities >100 mA cm?2 in electrolytes containing 0.1–1.5 M Lead(II) and methanesulfonic acid concentrations in the range 0–2.4 M; the solutions also contained 5 mM hexadecyltrimethylammonium cation, C16H33(CH3)3N+. From the viewpoint of the layer properties, the limitation is stress within the deposit Leading to cracking and lifting away from the substrate; the stress appears highest at high acid concentration and high current density. There are, however, other factors limiting the maximum current density for Lead Dioxide deposition, namely oxygen evolution and the overpotential associated with the deposition of Lead Dioxide. A strategy for operating the soluble Lead-acid flow battery is proposed.
Yuan Liu - One of the best experts on this subject based on the ideXlab platform.
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investigation on electrochemical properties of cerium doped Lead Dioxide anode and application for elimination of nitrophenol
2011Co-Authors: Yuan Liu, Huiling LiuAbstract:Abstract The present work focused on the investigation of electrochemical properties of cerium doped Lead Dioxide anode, i.e. Ti/Ce–PbO 2 . SEM, AFM, XRD and XPS were used to characterize the morphology, crystal structure and elemental states of the modified anode. Electrochemical impedance spectroscopy (EIS) was also utilized to study the electrochemical property of Ti/Ce–PbO 2 . The electrochemical activity of the Ti/Ce–PbO 2 anode was investigated by means of bulk electrolysis and compared with that of a PbO 2 anode. The accelerated life test and oxidants determination were also conducted. The results indicated that the incorporation of cerium improved the electrocatalytic activity and stability of PbO 2 anode. The service life of Ti/Ce–PbO 2 electrode was much longer than that of traditional Lead Dioxide electrode. The electrochemical activity obtained from degradation of o -nitrophenol ( o -NP) outperformed the traditional Lead Dioxide electrode as well. The Ti/Ce–PbO 2 electrode is considered a promising anode for the treatment of organic pollutants.
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comparison of degradation mechanism of electrochemical oxidation of di and tri nitrophenols on bi doped Lead Dioxide electrode effect of the molecular structure
2009Co-Authors: Yuan Liu, Huiling Liu, Xi WangAbstract:Abstract In the present work, the effect of molecular structures of di- and tri- nitrophenols on electrochemical degradation has been investigated on Bi-doped Lead Dioxide electrodes in terms of cyclic voltammetry and bulk electrolysis. The results of SEM and AFM displayed a porous structure with small-sized crystal particles and compact crystalline structure of Ti/Bi-PbO 2 . These nitrophenols were believed to be mainly degraded by means of indirect oxidation due to the low anodic oxidation currents observed in cyclic voltammetries and large amount of oxidants. And the absence of polymeric adhesive compounds formed and deposited on the surface of electrodes indicated the high electrocatalytic activity of Ti/Bi-PbO 2 for decomposing organics. Within the present experimental conditions used, almost complete elimination of nitrophenols was achieved. The electrochemical oxidation of them followed in the order: 2,6-dinitrophenol > 2,5-dinitrophenol > 2,4-dinitrophenol > 2,4,6-trinitrophenol. The relationship between electrochemical oxidation rate and the molecular structure of nitrophenols was discussed. The results of LC/MS and HPLC suggested that three kinds of intermediates were generated, i.e., polyhydroxylated intermediates, reduction products of nitrophenols and carboxylic acids. The possible degradation pathways of nitrophenols were proposed. The denitration and substitution by hydroxyl radicals on aromatic rings seemed to be the first stage. As a consequence, the formation of polyhydroxylated intermediates took place. These compounds were successively oxidized into catechol, resorcinol and hydroquinone, as well as reduced to aminophenols, followed by the opening of aromatic rings and the formation of a series of carboxylic acids. Finally, these carboxylic acids were oxidized into CO 2 and H 2 O.
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comparative study of the electrocatalytic oxidation and mechanism of nitrophenols at bi doped Lead Dioxide anodes
2008Co-Authors: Yuan Liu, Huiling LiuAbstract:Abstract The electrocatalytic oxidation of o -nitrophenol ( o -NP), m -nitrophenol ( m -NP) and p -nitrophenol ( p -NP) has been studied at Bi-doped Lead Dioxide anodes on acid medium by cyclic voltammetry and bulk electrolysis. The results of voltammetric studies indicated that these nitrophenol isomers were indirectly oxidized by OH radical in the solutions. Within the present experimental conditions used (50 mg of nitrophenol L −1 , pH 4.3, 30 mA cm −2 , 303 K), the complete decomposition of nitrophenols (NPs) was achieved. The electrocatalytic oxidation of NPs lay in the order: p -NP > m -NP > o -NP. Molecular configuration including the electron character and hydrogen bonds of NPs significantly influenced the electrocatalytic oxidation of these isomers. Hydroquinone, catechol, resorcinol, benzoquinone, aminophenols, glutaconic acid and maleic acid and oxalic acid have been detected as soluble products during the electrolysis of NPs. The possible degradation pathways of these isomers were proposed. The first stage is the release of nitro group from the aromatic rings. As a consequence, hydroquinone, catechol, resorcinol and benzoquinone are formed. These organic compounds are oxidized initially to carboxylic acids (glutaconic acid, maleic acid and oxalic acid) and later to carbon Dioxide and water. Simultaneously, the reduction of NPs to aminophenols takes place at the cathode.
Huiling Liu - One of the best experts on this subject based on the ideXlab platform.
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investigation on electrochemical properties of cerium doped Lead Dioxide anode and application for elimination of nitrophenol
2011Co-Authors: Yuan Liu, Huiling LiuAbstract:Abstract The present work focused on the investigation of electrochemical properties of cerium doped Lead Dioxide anode, i.e. Ti/Ce–PbO 2 . SEM, AFM, XRD and XPS were used to characterize the morphology, crystal structure and elemental states of the modified anode. Electrochemical impedance spectroscopy (EIS) was also utilized to study the electrochemical property of Ti/Ce–PbO 2 . The electrochemical activity of the Ti/Ce–PbO 2 anode was investigated by means of bulk electrolysis and compared with that of a PbO 2 anode. The accelerated life test and oxidants determination were also conducted. The results indicated that the incorporation of cerium improved the electrocatalytic activity and stability of PbO 2 anode. The service life of Ti/Ce–PbO 2 electrode was much longer than that of traditional Lead Dioxide electrode. The electrochemical activity obtained from degradation of o -nitrophenol ( o -NP) outperformed the traditional Lead Dioxide electrode as well. The Ti/Ce–PbO 2 electrode is considered a promising anode for the treatment of organic pollutants.
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comparison of degradation mechanism of electrochemical oxidation of di and tri nitrophenols on bi doped Lead Dioxide electrode effect of the molecular structure
2009Co-Authors: Yuan Liu, Huiling Liu, Xi WangAbstract:Abstract In the present work, the effect of molecular structures of di- and tri- nitrophenols on electrochemical degradation has been investigated on Bi-doped Lead Dioxide electrodes in terms of cyclic voltammetry and bulk electrolysis. The results of SEM and AFM displayed a porous structure with small-sized crystal particles and compact crystalline structure of Ti/Bi-PbO 2 . These nitrophenols were believed to be mainly degraded by means of indirect oxidation due to the low anodic oxidation currents observed in cyclic voltammetries and large amount of oxidants. And the absence of polymeric adhesive compounds formed and deposited on the surface of electrodes indicated the high electrocatalytic activity of Ti/Bi-PbO 2 for decomposing organics. Within the present experimental conditions used, almost complete elimination of nitrophenols was achieved. The electrochemical oxidation of them followed in the order: 2,6-dinitrophenol > 2,5-dinitrophenol > 2,4-dinitrophenol > 2,4,6-trinitrophenol. The relationship between electrochemical oxidation rate and the molecular structure of nitrophenols was discussed. The results of LC/MS and HPLC suggested that three kinds of intermediates were generated, i.e., polyhydroxylated intermediates, reduction products of nitrophenols and carboxylic acids. The possible degradation pathways of nitrophenols were proposed. The denitration and substitution by hydroxyl radicals on aromatic rings seemed to be the first stage. As a consequence, the formation of polyhydroxylated intermediates took place. These compounds were successively oxidized into catechol, resorcinol and hydroquinone, as well as reduced to aminophenols, followed by the opening of aromatic rings and the formation of a series of carboxylic acids. Finally, these carboxylic acids were oxidized into CO 2 and H 2 O.
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comparative study of the electrocatalytic oxidation and mechanism of nitrophenols at bi doped Lead Dioxide anodes
2008Co-Authors: Yuan Liu, Huiling LiuAbstract:Abstract The electrocatalytic oxidation of o -nitrophenol ( o -NP), m -nitrophenol ( m -NP) and p -nitrophenol ( p -NP) has been studied at Bi-doped Lead Dioxide anodes on acid medium by cyclic voltammetry and bulk electrolysis. The results of voltammetric studies indicated that these nitrophenol isomers were indirectly oxidized by OH radical in the solutions. Within the present experimental conditions used (50 mg of nitrophenol L −1 , pH 4.3, 30 mA cm −2 , 303 K), the complete decomposition of nitrophenols (NPs) was achieved. The electrocatalytic oxidation of NPs lay in the order: p -NP > m -NP > o -NP. Molecular configuration including the electron character and hydrogen bonds of NPs significantly influenced the electrocatalytic oxidation of these isomers. Hydroquinone, catechol, resorcinol, benzoquinone, aminophenols, glutaconic acid and maleic acid and oxalic acid have been detected as soluble products during the electrolysis of NPs. The possible degradation pathways of these isomers were proposed. The first stage is the release of nitro group from the aromatic rings. As a consequence, hydroquinone, catechol, resorcinol and benzoquinone are formed. These organic compounds are oxidized initially to carboxylic acids (glutaconic acid, maleic acid and oxalic acid) and later to carbon Dioxide and water. Simultaneously, the reduction of NPs to aminophenols takes place at the cathode.