- Electrodeposition of PbTe thin films from acidic nitrate baths
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Electrodeposition of PbTe thin films from an acidic nitric bath was systematically investigated to understand the kinetics and the effect of electrodeposition conditions on film composition, crystallographic structure, texture and grain size. The electroanalytical studies employed initially with a rotating disk electrode to investigate the kinetics associated with Te, Pb and PbTe electrodeposition. The results indicated that the PbTe thin films were obtained by the underpotential deposition (UPD) of Pb atoms onto the overpotentially deposited Te atoms on a substrate. Based on these studies, PbTe thin films were potentiostatically electrodeposited using e-beam evaporated gold thin films on silicon substrate to investigate the effect of various deposition conditions on film composition and microstructure. The data indicated that the microstructure, composition and preferred film growth orientation of PbTe thin films strongly depended on the applied potential and electrolyte concentration. At -0.12 V, the film was granular, dense, and preferentially oriented in the [1 0 0] direction. At potentials more negative than -0.15 V, the film was dendritic and preferentially oriented in the [2 1 1] direction. A smooth, dense and crystalline film with nearly stoichiometric composition was obtained at -0.12 V from a solution containing 0.01 M HTeO2+, 0.05 Pb2+ and 1 M HNO3.
- Xiao, Feng,Yoo, Bongyoung,Ryan, Margaret A.,Lee, Kyu-Hwan,Myung, Nosang V.
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- Movement of the deposit segment in thin layer electrochemical cell - A conjugate dissolution/deposition behavior
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In this paper we report a novel phenomenon taking place in the thin layer electrodeposition of Pb. A segment of dendrite deposit, which was segregated from the cathode, moved and shortened spontaneously in the electrochemical cell. We find that this behavior arises from the concurrent electrodissolution and electrodeposition reactions taking place at two ends of the isolated segment of the deposits. A mechanism inducing this phenomenon is suggested.
- Sun, Bin,Zou, Xian-Wu,Jin, Zhun-Zhi
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- Surface tension effect on the mechanical properties of nanomaterials measured by atomic force microscopy
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The effect of reduced size on the elastic properties measured on silver and lead nanowires and on polypyrrole nanotubes with an outer diameter ranging between 30 and 250 nm is presented and discussed. Resonant-contact atomic force microscopy (AFM) is used
- Cuenot, Stephane,Fretigny, Christian,Demoustier-Champagne, Sophie,Nysten, Bernard
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- Preparation of PbTe-based materials through thermal decomposition of lead acetate
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This paper examines the possibility of producing microstructured lead telluride with a high grain- boundary density through the thermal decomposition of lead acetate in the presence of tellurium under a reducing atmosphere, followed by cold compaction of the powder and hot pressing of the green compacts. The formation of fine lead telluride particles was followed using differential thermal analysis and thermo-gravimetry. Electron microscopy, X-ray microanalysis, and specific surface area measurements were used to assess the conductivity and size of the powder particles and the structure and composition of the grains in the hot-pressed samples in relation to the preparation conditions and starting-mixture composition. Pleiades Publishing, Ltd., 2012.
- Leontyev,Ivanova,Bente,Gremenok
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- Effect of screening current induced pair breaking on magnetization of superconducting lead nanoparticles
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Magnetization measurements on lead nanoparticles in the size range 35-45 nm are presented. It is shown that the critical fields in these nanoparticles are enhanced significantly above their bulk values with temperature dependence also distinct from that o
- Yashwant,Prajapat,Jayakumar,Singh,Gupta,Tyagi,Ravikumar
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- Superconducting properties of lead nanowires fabricated by electrochemical deposition
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Pb nanowires were fabricated by electrochemical deposition inside the nanopores of polycarbonate membranes. The diameter of fabricated nanowires ranged from 80 to 100 nm, and length is 5 μm on average. Temperature dependence of resistance was measured in magnetic fields by two-point contact method. It is found that the nanowires show a broad transition with higher critical fields compared with typical values of bulk Pb, and that the nanowires belong to Type II superconductors.
- Ishii,Sadki,Ooi,Ochiai,Hirata
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- Electrodeposition of PbSe onto n-Si(1 0 0) wafers
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PbSe was electrodeposited onto monocrystalline n-Si(1 0 0) wafers from 50 mM Pb(NO3)2 + 2 mM SeO2 + 0.1 M HNO3 solution. The mechanism of PbSe electrocrystallization on n-Si was studied. At initial stage, 3D Pb and 3D Se nuclei are simultaneously codeposited onto Si at potentials more negative than Si flat band potential and chemically interact resulting in PbSe formation. When n-Si/PbSe heterostructure is formed, the overvoltage of bulk lead deposition increases, as a result of redistribution of electrode potential. Further growth of PbSe is realized due to underpotential deposition (UPD) of Pb and overpotential deposition (OPD) of Se onto formed PbSe nuclei. With Pb UPD shift increase, amorphous Se inclusion is registrated in the deposit. When 2D Pb nucleation mechanism is changed to 3D mode, metal Pb cubic phase is codeposited with PbSe. Electrodeposition of PbSe onto n-Si is irreversible. PbSe anodic stripping does not take place in the dark due to the barrier on solid interface. Oxidation of PbSe on n-Si is observed only under illumination, when photoholes are generated in silicon substrate.
- Ivanova,Ivanou,Streltsov
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- STM studies of real and quasi-perfect silver single crystal surfaces used in electrochemical experiments
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Real and quasi-perfect silver single crystal surfaces, which have been used intensively in different electrochemical investigations, are studied by scanning tunneling microscopy (STM) to determine the surface profile on an atomic level. The measurements were carried out on chemically polished macroelectrodes and electrolytically grown microelectrodes in contact with air as well as under potentially controlled electrochemical conditions. The real macroelectrodes show a much higher surface corrugation than the quasi-perfect microelectrodes which have large atomically flat terraces separated by monatomic steps. The possibility of observing the dynamics of monatomic steps under anodic and cathodic polarization conditions on quasi-perfect single crystal surfaces is demonstrated. Nucleation and crystal growth processes are observed by means of in situ STM investigations of lead electrodeposition on Ag(111) macroelectrodes. The results demonstrate the possibility of studying fundamentally the initial steps of electrocrystallization by in situ STM under well-defined electrochemical conditions.
- Hoepfner, M.,Obretenov, W.,Juettner, K.,Lorenz, W. J.,Staikov, G.,et al.
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- Tuning the Architecture of Mesostructures by Electrodeposition
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When the dimension of materials decreases to mesoscale, their properties can change dramatically, depending on the boundary conditions imposed by the sample architecture including geometry, morphology, and hierarchical structures. Here we show that electrodeposition, a method for reducing materials from a solution onto a substrate, can provide a versatile pathway to tailor the architecture of mesostructures. Novel lead (Pb) structures ranging from nanowires, mesoparticles with octahedral, decahedral, and icosahedral shapes to porous nanowires, multipods, nanobrushes, and even snowflake-shaped structures were synthesized through systematically exploring electrodeposition parameters including reduction potentials, solution concentration, starting materials, supporting electrolytes, and surfactants. Copyright
- Xiao, Zhi-Li,Han, Catherine Y.,Kwok, Wai-Kwong,Wang, Hsien-Hau,Welp, Ulrich,Wang, Jian,Crabtree, George W.
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- 1D-transport properties of single superconducting lead nanowires
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We report on the transport properties of single superconducting lead nanowires grown by an electrodeposition technique, embedded in a nanoporous track-etched polymer membrane. The nanowires are granular, have uniform diameter of ?40 nm and a very large aspect ratio (?500). The diameter of the nanowire is small enough to ensure a 1D superconducting regime in a wide temperature range below Tc. The non-zero resistance in the superconducting state and its variation caused by fluctuations of the superconducting order parameter were measured versus temperature, magnetic field, and applied DC current (or voltage). The current induced breakdowns in the V-I characteristics may be explained by the formation of phase slip centers. Moreover, DC voltage driven measurements reveal the existence of a new S-shape behavior near the formation of these phase slip centers.
- Michotte,Mátéfi-Tempfli,Piraux
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- Combustion of some zinc-fuelled binary pyrotechnic systems
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Combustion stuides of several binary pyrotechnic systems using zinc as fuel and one of the oxidants: PbO2, Pb3O4, PbO, BaO2, SrO2 or KMnO4, are reported. Combustion was very sensitive to compaction, and only mixturesof Zn/PbO2, Zn/Pb3O4 and Zn/KMnO4 susta
- Tribelhorn, Michael J.,Venables, Dean S.,Brown, Michael E.
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- Four new lead(II) thiolate cluster complexes - Unexpected products of a conventional synthesis
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The reaction of Pb(OOCCH3)2·3H2O with 2.1 equiv. of HS-2,6-(CH3)2C6H 3 in ethanol/water is expected to give [Pb{S-2,6-(CH 3)2C6H3}2]. However, we obtained an orange powder whose elemental analysis disagrees with that of the expected product and indicates small amounts of oxygen. Layering of concentrated solutions of this orange powder in dry THF with pentane under nitrogen results in the formation of a mixture of three identifiable crystalline compounds, namely [Pb10{S-2,6-(CH3) 2C6H3}20], [Pb 6S{S-2,6-(CH3)2C6H3} 10(C4H8O)4] and [Pb 8O2{S-2,6-(CH3)2C6H 3}12]. In contrast, fractional crystallization from dilute solutions initially yielded only yellow crystals of [Pb 14O6{S-2,6-(CH3)2C6H 3}16]. Further concentration of the supernatant solution yielded, upon layering with pentane, [Pb6S{S-2,6-(CH 3)2C6H3}10(C 4H8O)4] and [Pb10{S-2,6-(CH 3)2C6H3}20] which are almost completely separable by controlling the duration of the crystallization step and the amount of condensed pentane. Recrystallization of the crude orange powder under aerobic conditions produces pure [Pb14O 6{S-2,6-(CH3)2C6H3) 16] with a yield five times higher than that under nitrogen. This shows that it is sensitive to oxidation by oxygen in solution. The structures of all four complexes have been determined by single-crystal X-ray analysis. The net formed by the six oxygen and twelve lead atoms in the center of [Pb 14O6{S-2,6-(CH3)2C6H 3}16] resembles a small piece of a layer of the solid-state structure of red PbO. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.
- Eichhoefer, Andreas
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- Changes in surface stress of gold electrode during underpotential deposition of Pb
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The changes in surface stress of a gold film electrode during underpotential deposition (UPD) of lead in pH 3.0, 0.5 M NaClO4 solution containing 10-4 MPb(ClO4)2 or PbCl2 were measured by a bending beam method to investigate the relation between surface stress and structural change of the Pb-UPD layer. A maximum in the surface stress vs. potential curve like an electrocapillary curve emerged at the onset of the UPD. Moreover, a hump in the surface stress vs. potential curve also emerged in the range of surface coverage of Pb from θpb = 0.4 to 0.8 during the UPD process. The changes in surface stress were plotted vs. cathodic charge required for Pb-UPD. Two linear and one plateau region appeared in the surface stress vs. the cathodic charge curve. The plateau region corresponded to the hump in the surface stress vs. potential curve. It was deduced from the comparison with the scanning tunnel microscopy, atomic force microscopy, and surface X-ray scattering spectroscopy results in the literature that the plateau region is associated with the change in rotation angle from R = 0° to 2.5° of incommensurate hexagonal close-packed Pb layer. Particularly, it was emphasized that the hump resulted from the release of compressive surface stress due to the change in rotation angle of the UPD layer.
- Seo, Masahiro,Yamazaki, Makiko
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- Recovery of Cu, Pb, Cd and Zn from synthetic mixture by selective electrodeposition in chloride solution
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Secondary fly ash, resulting from thermal treatment processes, leads to a highly concentrated chloride solution with Cu, Pb, Cd and Zn as main heavy metals when dissolved in water. The selective electrodeposition of these heavy metals has been studied in this work. The goal was to recover, under potentiostatic conditions, each heavy metal with high purity, yield and reaction rates. By changing the parameters pH and overpotential, an optimum of the three requirements was looked for. In general, Cu, Pb and Cd could be separated with purities of 99 mol% or higher. Underpotential deposition was supposed to be the main reason for the impurities in case of Cu and Pb deposition. H+ reduction as side reaction could be kept small for Cu, Pb and Cd even at lower pH by carefully selecting the overpotential. The quality of the deposits obtained depended strongly on the overpotential, but hardly on the pH. The deposits of Cu, Pb and Cd were easily removable from the cathode due to a dendritic growth mechanism. Zn deposits showed compact growth and adhered to the electrode surface. In addition, the structure of the deposits, revealed by scanning electron microscope (SEM), was compared with the current transients during electrodeposition. An enhancement factor r was introduced in order to compare the different deposition rates.
- Doulakas,Novy,Stucki,Comninellis, Ch.
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- Electrochemical quartz crystal microgravimetry study of metal deposition from EDTA complexes
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The electrochemical deposition of metals from MeII (ethylenediaminetetraacetic acid, EDTA) complexes was studied by electrochemical quartz crystal microgravimetry. These investigations are important for the development of environmental clean-up processes, such as remediation of metal-contaminated soils by EDTA and subsequent electrochemical recovery of metal, in situ electrokinetic soil remediation, electrochemical gas purification, etc. Deposition of metals frequently encountered in hazardous waste sites, such as Pb, Cu, Cd, Zn, and Ni, was investigated. The potential regions of metal deposition were detected from a distinct increase in electrode mass. We observed reduction of Pb, Cu, Cd, and Zn from both protonated and nonprotonated EDTA complexes. No indications were found for Ni deposition. While diffusion-limited currents of Cu, Cd, and Pb deposition could be achieved, the Zn deposition current was much lower. This can be explained in terms of electrode passivation during Zn deposition. Side reactions were identified, namely, proton reduction, EDTA reduction, and water decomposition.
- Juzeliunas, Eimutis,Pickering, Howard W.,Weil, Konrad G.
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- Methanol oxidation at platinized lead coatings prepared by a two-step electrodeposition-electroless deposition process on glassy carbon and platinum substrates
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Platinized lead deposits, Pt(Pb), have been formed on glassy carbon (GC) and platinum electrodes by a two-step process, whereby a controlled amount of Pb was electrodeposited onto the substrates and was subsequently coated with a thin Pt layer upon immersion of the Pb/GC or Pb/Pt electrodes into a chloroplatinic acid solution. The spontaneous surface replacement of Pb by Pt resulted in Pt(Pb)/GC or Pt(Pb)/Pt electrodes which consisted of dispersed Pt(Pb) particles and displayed typical Pt surface electrochemistry in deaerated acid solutions. When tested as methanol oxidation anodes, these electrodes exhibited enhanced electrocatalytic activity both during voltammetric and constant potential experiments. This behaviour is attributed to an electronic effect of the underlying Pb onto the Pt surface layer.
- Papadimitriou,Tegou,Pavlidou,Kokkinidis,Sotiropoulos
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- Thermal decomposition of natural and synthetic plumbojarosites: Importance in 'archeochemistry'
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Plumbojarosite and argentoplumbojarosite were sources of lead and silver in ancient and medieval times. The understanding of the chemistry of the thermal decomposition of these minerals is of vital importance in 'archeochemistry'. The thermal decomposition of plumbojarosite was studied using a combination of thermogravimetric analysis coupled to a mass spectrometer. Three mass loss steps are observed at 376, 420 and 502°C. These are attributed to dehydroxylation, loss of sulphate occurs at 599°C, and loss of oxygen and formation of lead occurs at 844 and 953°C. The temperatures of the thermal decomposition of the natural jarosite were found to be less than that for the synthetic jarosite. This is attributed to a depression of freezing point effect induced by impurities in the natural jarosite. Raman spectroscopy was used to study the structure of plumbojarosite. Plumbojarosites are characterised by stretching bands at 1176, 1108, 1019 and 1003 cm-1 and bending modes at 623 and 582cm-1. Changes in the molecular structure during thermal decomposition were followed by infrared emission spectroscopy. The technique shows the loss of intensity in the hydroxyl stretching region attributed to dehydroxylation. Loss of sulphate only occurs after dehydroxylation. Lead is formed at higher temperatures through oxygen evolution.
- Frost, Ray L.,Wills, Rachael-Anne,Weier, Matt L.,Musumeci, Anthony W.,Martens, Wayde
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- Electrodeposition of lead on ITO electrode: Influence of copper as an additive
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The reversible electrodeposition of metallic lead onto indium-tin oxide coated glass (ITO) was investigated and the influence of Cu(NO3) 2-3H2O as additive was evaluated. The presence of Cu 2+ in the electrolytic solution produces a higher variation in the optical transmissivity. The optical response of the system changes from 85 to 10% relative to the ITO coated substrate. The kinetics of the electroreduction process of the Pb2+ and Cu2+ from the electrolytes has been determined by electrochemical impedance spectroscopy (EIS) at different electrodeposition potentials. This system may be a promising candidate for electrochromic materials.
- Avellaneda, César O.,Napolitano, Marcos A.,Kaibara, Evandro K.,Bulh?es, Luis O. S.
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- Phase transformation and percolation effect in PbO2-1/12Ag2O-xC system
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The structure and electronic transport properties have been investigated for composite PbO2-1/12Ag2O-xC (0 ≤ x ≤ 2) materials prepared by mechanical milling in an O2 atmosphere. The solid-state reactions result in the occurrence of abundant phase transformations, when the graphite content increases. With the phase transformations occurring, the percolation effect is observed for the electronic transport of PbO2-1/12Ag2O-xC system, while its conductivity undergoes an insulator-metal transition. The percolation threshold is determined by DC conductivity measurement and analysis of X-ray diffraction patterns.
- Li,Zhang,Geng,Li,Song,Qiao,Wang
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- Effect of oxidation conditions on the phase composition, structure, and properties of photosensitive lead sulfide layers
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The oxidation of single-crystal and polycrystalline lead sulfide was studied as a function of process duration and temperature. The phase changes during oxidation were followed by thermal analysis, x-ray diffraction, and x-ray photoelectron spectroscopy. The transport properties of as-grown and oxidized PbS layers were measured. A mechanism was proposed for the bulk and surface processes resulting in the formation of photosensitive PbS-based structures.
- Kamchatka,Chashchinov,Chesnokova
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- Study of the current efficiency decrease accompanying short pulse time for pulse plating
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This investigation is concerned with the variation of current efficiency under pulse current conditions. The parameters involve the pulse current density, the on-time, and the off-time. When the on-time is shorter than a critical pulse time, the efficiency drops noticeably. A model based on successive charge transfer steps and a side reaction is proposed to explain the experimental observations.
- Chen,Wan
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- Pb electrodeposition on polycrystalline Cu in the presence and absence of Cl-: A combined oblique incidence reflectivity difference and in situ AFM study
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Oblique incidence reflectivity difference (OI-RD) measurements reveal differences in the earliest stages of overpotential-deposited (OPD) growth between Pb electrodeposition on polycrystalline Cu surfaces in the presence and absence of Cl-. At moderate overpotentials, when only 100 mM ClO4- is present, the magnitude of the real part of the OI-RD signal continues to increase after completion of the first underpotential-deposited (UPD) Pb monolayer, but with the addition of 20 mM KCl the magnitude decreases after the UPD monolayer forms. In situ atomic force microscopy (AFM) shows that in the former case the island density is much greater than in the latter. Using OI-RD as a probe, we show additionally that when the substrate potential is returned to a more positive potential in the presence of Cl-, the UPD Pb monolayer dissolves after the Pb islands disappear.
- Wu, Guang Yu,Bae,Gewirth,Gray,Zhu,Moffat,Schwarzacher
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- In situ STM studies of lead electrodeposition on graphite substrate
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Scanning tunneling microscopy (STM) was applied in solution to study the lead electrodeposition on single-crystal graphite electrode. The amount of deposited lead was varied from a few to a hundred monolayers. The atomic lattice of electrodeposited lead w
- Szklarczyk,Bockris
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- Interaction of Pb and Cd during anodic stripping voltammetric analysis at boron-doped diamond electrodes
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Highly boron-doped diamond (BDD) films were utilized for simultaneous electrochemical measurement of micromolar-level concentrations of Pb and Cd, and for the examination of their interactions. Differential pulse anodic stripping voltammetry (DPASV) was used for this detection. This approach can help to understand the possible detection of trace metals at BDD electrodes without the aid of mercury. These metals were found to strip at their characteristic potentials, in solutions containing Cd or Pb alone, and in those containing these metals together. The mixed solutions (concentration range: 1-5μM) yielded well-separated stripping peaks for Pb and Cd and the differential stripping peak currents for the respective metals increased linearly with increasing metal concentration. There were mutual interferences due to Pb-Cd interactions, but these can be taken into account with the aid of three-dimensional calibration plots. A model has been developed to help explain the Pb-Cd interactions.
- Manivannan,Kawasaki,Tryk,Fujishima
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- Tuning the architectures of lead deposits on metal substrates by electrodeposition
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Different morphologies of lead (Pb) deposited on different metal substrates have been prepared via electrochemical deposition in aqueous solution. The morphologies of as-deposited lead were determined by scanning electron microscope (SEM). It is found tha
- Yao, Chen-Zhong,Liu, Meng,Zhang, Peng,He, Xiao-Hui,Li, Gao-Ren,Zhao, Wen-Xia,Liu, Peng,Tong, Ye-Xiang
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- New approach for the removal of metal ions from water: Adsorption onto aquatic plants and microwave reaction for the fabrication of nanometals
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We adsorb heavy metal ions such as Ag+, Pb2+, and Ru3+ onto an aquatic plant and convert the adsorbed ions to the corresponding nanometallic particles by the polyol reaction carried out in a microwave oven. ? 2005 American Chemical Society.
- Chefetz,Sominski,Pinchas,Ginsburg,Elmachliy,Tel-Or,Gedanken
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- The fabrication and characterization of an ex situ plated lead film electrode prepared with the use of a reversibly deposited mediator metal
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In this paper an ex situ plated lead film electrode prepared with use of the mediator metal (Zn) was elaborated. The electrochemical method for lead film formation is based on a co-deposition of a metal of interest (Pb) with a reversibly deposited mediator metal (Zn) and then on an oxidation of zinc and further deposition of lead by the appropriate potential. This serves to increase the density of islands of lead atoms, promoting lead film growth. The lead-based sensors were characterized by optical method (atomic force microscopy (AFM)) and as well as cyclic, linear sweep and square wave voltammetry. The adsorptive system of folic acid was employed to investigate the electrochemical characteristics a novel type of lead film electrode. Well-formed stripping peaks and a linear dependence of the stripping current on the folic acid concentration were observed on the lead film electrode prepared with use of the mediator metal while comparative measurements attempted with the lead film electrode prepared without use of the mediator metal were unsuccessful.
- Tyszczuk, Katarzyna
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- Phenoxyalkanoic acid complexes. Part I. Complexes of lead(II), cadmium(II) and copper(II) with 4-chloro-2-methylphenoxyacetic acid (MCPA)
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New solid heavy metal complexes with 4-chloro-2-methylphenoxyacetic acid (MCPA) of the general formulae: Pb(MCPA)2· H2O and Cd(MCPA)2·2H2O have been prepared. Diffractometric, IR spectroscopic and thermal analyses of these complexes and the previously described Cu(MCPA)2 have been performed. The complexes have different structures, a low level of crystallinity and exhibit a tendency to form polymers. An attempt has been made to explain the mode of the ligand molecule coordination on the basis of the position of the bands of the characteristic vasym and vsym vibrations of the carboxylate group. The course of the TG, DTG and DTA curves indicates that the compounds decompose in two (the copper salt) or three stages. The decomposition of the cadmium complex is preceded by dehydration. The basic gaseous products of decomposition are H2O and CO2. HCOOH, HOCH 2COOH, HCl and trace amounts of compounds containing an aromatic ring were also detected. The final solid decomposition product is a metal oxide.
- Kobylecka,Ptaszynski,Rogaczewski,Turek
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- Reduction of PbS and Sb2S3 with elemental Fe and Mg in dusty plasma environment created during electrical discharge assisted mechanical milling (EDAMM)
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The newly developed synthesis technique of electrical discharge assisted mechanical milling (EDAMM) is used to reduce Pb and Sb sulfides using Fe and Mg as reduction agents. It is demonstrated that both Fe and Mg can successfully be used to fully reduce P
- Calka,Mosbah,Stanford,Balaz
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- Cathodic generation and oxidation of lead zintl ion Pb94- in potassium iodide solutions in liquid ammonia
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The electrochemical reduction of lead and oxidation reaction of the resulting Pb94- Zintl ions have been studied in 0.1 and 1.0 M KI solutions in liquid ammonia at -70°C. The reduction process is a complicated multistep reaction. Under certain conditions the oxidation of Pb94- occurs as a simple, electrochemically irreversible reaction for which the limiting current is diffusion controlled. The diffusion coefficient of Pb94- was determined from a combination of chronoamperometry measurements on a 25 μm Pt ultramicroelectrode and chronocoulometry measurements on a 1 mm Pb disk electrode. The chronocoulometric method for the determination of Pb94- determination is presented and used to determine the actual Pb94- concentrations in the electrochemical cell. Side effects, which accompany the reduction and oxidation reactions, have also been studied and the ways to avoid them presented.
- Chlistunoff, Jerzy B.,Lagowski, Joseph J.
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- Atomic resolution of carbon and lead atoms from measurements made in solution
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STM is rapidly evolving into a powerful technique for a wide application to study electrochemical systems. The aim of this communication is to show that atomic resolution in electrolyte solution for different materials than HOPG is possible. In this note
- Szklarczyk,Velev,Bockris
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- Boundary effect on superconductivity in long single-crystal superconducting nanowires
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We fabricate single-crystal Pb, Sn, and Zn nanowires, of length 6 or 60 μm and diameter 30-250 nm, using an in situ template-based electrochemical method. In this approach, a single nanowire is formed in contact with a pair of bulk film electrodes of Au, Sn, or Pb. We observe that, with superconducting electrodes having a higher critical temperature Tc, superconductivity is induced in Sn and Zn nanowires at the Tc of the electrodes for nanowires as long as 60 μm. With Au electrodes, superconductivity is suppressed completely in 6 μm-long nanowires and partially in 60 μm-long nanowires. Based on transmission electron microscopy studies, the nanowires are single crystalline. Analysis of the temperature dependence of the normalized resistance suggests that the residual-resistance-ratio plays an important role in the observed anomalous long-range proximity effect.
- Liu, Haidong,Ye, Zuxin,Luo, Zhiping,Rathnayaka,Wu, Wenhao
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- EFFECT OF RHODAMINE-B ON THE ELECTRODEPOSITION OF LEAD ON COPPER.
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Rhodamine-B chloride has been used as a model plating additive in a study of the electrodeposition of Pb from 1M NaClO//4, 0. 5 and 5 mM Pb** plus ** plus (pH 3) on Cu. Ellipsometer measurements during cyclic voltammetry have shown that the addition of dye results in a more compact bulk deposit than obtained in its absence. It also prevents complete monolayer coverage during formation of the Pb underpotential deposit and shifts the bulk deposition peak to more cathodic potentials during the first potential cycle. Due effects on potential and micromorphology disappear during subsequent cycling, but reappear after relaxation periods at open circuit. Depletion and readsorption of dye on the surface have been confirmed by spectroscopic ellipsometry. Different optical film models have been investigated for the interpretation of spectroscopic ellipsometer measurements by use of multidimensional analysis.
- Farmer,Muller
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- Microscopic and electrochemical characterization of lead film electrode applied in adsorptive stripping analysis
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Lead film electrodes (PbFEs) deposited in situ on glassy carbon or carbon paste supports have recently found application in adsorptive stripping voltammetric determination of inorganic ions and organic substances. In this work, the PbFE, prepared in ammon
- Bobrowski, Andrzej,Kalcher, Kurt,Kurowska, Katarzyna
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- A rapid and simple route for the synthesis of lead and palladium nanoparticles in tetrazolium based ionic liquid
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In the present work, we report a novel method for the synthesis of palladium and lead nanoparticles by the reduction method in tetrazolium ring based ionic liquid. Palladium and lead nanoparticles so-prepared were well characterized by powder X-ray diffraction measurements (pXRD), transmission electron microscopy (TEM) and quasi elastic light scattering (QELS) techniques. Powder X-ray diffraction (pXRD) analysis revealed all relevant Bragg's reflection for crystal structure of palladium and lead. Powder X-ray diffraction plots also revealed no oxidized material of palladium and lead nanoparticles. TEM showed nearly uniform distribution of the particles in methanol and confirmed by QELS. Typical applications of palladium nanoparticles include in vitro use and sensor design applications. Palladium nanoparticles is also ideal for spin coating, self-assembly and monolayer formation. Palladium nanoparticles can also be considered as potential new catalysts.
- Singh, Prashant,Kumar, Pradeep,Kumari, Kamlesh,Sharma, Pankaj,Mozumdar, Subho,Chandra, Ramesh
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- [PbAsSiiPr3]6 - The first structurally characterized compound with chemical bonds between lead and arsenic
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The compound [PbAsSiiPr3]6 (1) could be obtained by the reaction of PbCl2 with iPr3SiAs(SiMe3) 2 in THF at 0°C. Central structural motif is a hexagonal prism built by six lead and six arsenic atoms. The average Pb-As bond length is 281 pm. The cluster crystallizes in the monoclinic space group C2/c, the lattice constants are: a = 4460.8(9) b = 2296.6(5), c = 2734.4(6) pm, β = 117.57(3)°. The thermogravimetric analysis in vacuum shows the tendecy of 1 to decompose under formation of elementary lead and volatile arsenic compounds.
- Von Haenisch, Carsten,Nikolova, Donna
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- Construction of highly oriented self-assembled monolayer of alkyldithiol with ferrocene on gold (111) using underpotentially deposited lead submonolayer as a template
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Highly oriented self-assembled monolayer (SAM) of alkyldithiol with a ferrocene group was constructed on Au(111) surface using underpotentially deposited (UPD) Pb submonolayer as a template. Orientation of this SAM was confirmed by comparing amounts of ferrocene moiety and Au-S bonding. Copyright
- Kondo, Toshihiro,Sato, Saori,Maeda, Wakana
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- Molecular lead clusters - From unexpected discovery to rational synthesis
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Feats of lead: The cluster compounds [Pb12Hyp6] (1; see structure) and [Pb10Hyp6] (2) result from the reaction of the plumbylene [Pb{Si(SiMe3)3}2] ([PbHyp2]) with hydride sources, such as PH3 or [{(Ph 3P)CuH}6]. They are the first examples of neutral lead clusters bearing σ-bonded substituents. Whereas 2 is isolated from the reaction mixture on a multigram scale, 1 is only obtained in traces.
- Klinkhammer, Karl W.,Xiong, Yun,Yao, Shenglai
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- Employing Polar Solvent Controlled Ionization in Precursors for Synthesis of High-Quality Inorganic Perovskite Nanocrystals at Room Temperature
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All inorganic cesium lead halide (CsPbX3, X = Cl, Br, I) perovskite nanocrystals (PeNCs) are synthesized by employing polar solvent controlled ionization (PCI) method in precursors. The new strategy can be easily carried out at room temperature and allow to employ smaller amount of weaker polarity and a broader range of low-boiling low-toxic solvents. The as prepared CsPbX3 PeNCs reveal tunable emission spectra from 380 to 700 nm and high quantum yields over 80% with narrow full width at half maximum (FWHM). Meanwhile, larger “effective Stokes shifts” of PeNCs in PCI method, which enlarges 200% more than other PeNCs in regular methods, are observed. Most interestingly, the PeNCs growth process is coupling with some typical crystals formations. The main morphologies of CsPbI3 PeNCs are hybrid of nanorods and nanoparticles. The primary morphologies of CsPbBrxI3- x and CsPbBr3 PeNCs are nanowires, which are supposed to have great potentials for applying in laser arrays and highly sensitive photodetector applications. Furthermore, such superior optical is endowed to fabricate white light emitting diodes, which has wide color gamut covering up to 120% of the National Television Systems Committee color standard.
- Fang, Fan,Chen, Wei,Li, Yang,Liu, Haochen,Mei, Ming,Zhang, Ruan,Hao, Junjie,Mikita, Marus,Cao, Wanqiang,Pan, Ruikun,Wang, Kai,Sun, Xiao Wei
-
-
- Influence of halide mixing on thermal and photochemical stability of hybrid perovskites: XPS studies
-
The effect of I–/Cl–and I–/Br–mixing on the thermal and photochemical degradation of organometallic perovskite MeNH3PbI3 (MAPbI3) was studied by X-ray photoelectron spectroscopy, which revealed the opportunity to essentially increase the photo and thermal stabilities of the material depending on the level and position of halide-mixing. The largest positive effect was observed for the small concentration of chloride substituent (MAPbI2.7Cl0.3), while the full halide substitution (MAPbBr3) had a negative effect on the stability of hybrid perovskite.
- Zhidkov, Ivan S.,Akbulatov, Azat F.,Kukharenko, Andrey I.,Cholakh, Seif O.,Stevenson, Keith J.,Troshinb, Pavel A.,Kurmaev, Ernst Z.
-
p. 381 - 383
(2018/08/10)
-
- The Triboracyclopropenyl Dianion: The Lightest Possible Main-Group-Element Hückel π Aromatic
-
Hückel π aromaticity is typically a domain of carbon-rich compounds. Only very few analogues with non-carbon frameworks are currently known, all involving the heavier elements. The isolation of the triboracyclopropenyl dianion is presented, a boron-based analogue of the cyclopropenyl cation, which belongs to the prototypical class of Hückel π aromatics. Reduction of Cl2BNCy2 by sodium metal produced [B3(NCy2)3]2-, which was isolated as its dimeric Na+ salt (Na4[B3(NCy2)3]22 DME; 1) in 45 % yield and characterized by single-crystal X-ray diffraction. Cyclic voltammetry measurements established an extremely high oxidation potential for 1 (Epc=-2.42 V), which was further confirmed by reactivity studies. The Hückel-type π aromatic character of the [B3(NCy2)3]2- dianion was verified by various theoretical methods, which clearly indicated π aromaticity for the B3 core of a similar magnitude to that in [C3H3]+ and benzene.
- Kupfer, Thomas,Braunschweig, Holger,Radacki, Krzysztof
-
supporting information
p. 15084 - 15088
(2016/01/25)
-
- Synthesis and physicochemical characterization of two lead(II) complexes with O-, N-donor ligands. Lone pair functionality and crystal structure
-
A dinuclear [Pb2(4-CHO-5-MeIm)6(NO3)2](NO3)2 (1) and a polynuclear [Pb(2-pzc)2(H2O)]n (2) complexes (where 5(4)-carbaldehyde-4(5)-methylimidazole (5(4)-CHO-4(5)-MeIm) and pyrazine-2-carboxylic acid (2-pzcH)) have been synthesized and characterized by elemental analysis, IR spectroscopy and X-ray crystallography. Structural determination for complex 1 reveals a cationic species [Pb(4-CHO-5-MeIm)3]2+ connected through bridging nitrate(V) ions. There are also an uncoordinated nitrate ions as counterions. Complex 2 is a three-dimensional architecture consisting of Pb6O12 building units. The pyrazine-2-carboxylato ligand behaves as a chelating agent and a bi-connective bridge. The coordination polyhedra around lead(II) ion could be described as a distorted docecahedron (1) or monocapped trigonal prism (2). The luminescent properties of 1 and 2 investigated in the solid state at room temperature indicate structure-dependent photoluminescent properties. The DFT calculations and the X-ray structural data point on rather hemidirected type of coordination around Pb(II) ions of 1 and 2.
- Masternak, Joanna,Barszcz, Barbara,Hodorowicz, Maciej,Khavryuchenko, Oleksiy V.,Majka, Alina
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p. 1998 - 2007
(2015/03/30)
-
- Producing hierarchical porous carbon monoliths from hydrometallurgical recycling of spent lead acid battery for application in lithium ion batteries
-
In this paper, an environmentally clean process to recycle the paste from a spent lead acid battery (LAB) is further developed in order to produce a porous carbon anode material for a lithium ion battery (LIB) which is currently under increasing focus as the solution for future energy storage and distribution networks. Using lead citrate from hydrometallurgical leaching of lead paste as a precursor, electrochemically active carbon materials were produced as a new product with hierarchical open sponge-like porosity. It was found that anode materials made from porous carbon by pyrolysing lead citrate at 500 °C, with high micropore (3 g-1) and BET surface area (138.5 m2 g-1), showed remarkable reversible capacity values beyond intercalation at both low and high current densities. In particular, at the high current density of 5000 mA g-1 (13.4 C, according to the theoretical capacity of 372 mA h g-1), a high discharge capacity of 217 mA h g-1 was maintained even after 200 cycles, which is much superior in comparison with other carbon materials.
- He, Xiong,Peng, Xiaoyu,Zhu, Yuxuan,Lai, Chao,Ducati, Caterina,Kumar, R. Vasant
-
p. 4637 - 4646
(2015/09/15)
-
- Stable plumbylene dichalcogenolate monomers with large differences in their interligand angles and the synthesis and characterization of a monothiolato Pb(II) bromide and lithium trithiolato plumbate
-
The complexes, Pb(ChArPri4)2 (Ch = O (1), S (2); ArPri4 = C6H3-2,6-(C6H 3-2,6-Pri2)2) were synthesized by alcoholysis and salt metathesis routes and represent the first fully characterized monomeric, two-coordinate, lead dichalcogenolates in the solid state. Structural studies showed that the S-Pb-S angle (77.21(4)) is about 22 narrower than the corresponding O-Pb-O angle. 207Pb NMR and electronic spectroscopy show that the separation between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) decreases from the bisaryloxo plumbylene to the bisthiolato derivative. Reaction of LiSArMe6 with PbBr2 in a 2:1 ratio led not to Pb(SArMe6)2, but to a mixture of the monothiolato lead(II) complex, {Pb(Br)(μ-SArMe6)}2 (3) and the lithium tristhiolato plumbate, LiPb(SArMe6)3 (4). 3 and 4 were isolated and purified by fractional recrystallization, and both were characterized by X-ray crystallography and spectroscopic studies.
- Rekken, Brian D.,Brown, Thomas M.,Olmstead, Marilyn M.,Fettinger, James C.,Power, Philip P.
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p. 3054 - 3062
(2013/05/08)
-
- Lead citrate precursor route to synthesize nanostructural lead oxide from spent lead acid battery paste
-
Nanostructural lead oxides were prepared by the decomposition of a new type of lead citrate precursor (Pb3(C6H5O 7)2·3H2O), which was synthesized through leaching of spent lead acid battery paste in citrate salt aqueous system and more economical compared with former precursor (Pb(C6H 6O7)·H2O). The products were characterized by thermogravimetric-differential thermal analysis, scanning electron microscopy and X-ray diffraction. The results show that when lead citrate of columnar-shape crystals are calcined in N2 gas, orthorhombic β-PbO is the main product containing small amount of Pb and C. On combusting the citrate in air, a mixture of orthorhombic β-PbO, tetragonal α-PbO and Pb with the particle size of 100-200 nm is obtained, with β-PbO as the major product. And the cyclic voltammetry measurements of lead oxides present different electrochemical redox potentials because of the different structure of lead oxide obtained from Pb3(C 6H5O7)2·3H2O.
- Li, Lei,Hu, Yuchen,Zhu, Xinfeng,Yang, Danni,Wang, Qin,Liu, Jianwen,Kumar, R. Vasant,Yang, Jiakuan
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p. 1700 - 1708
(2013/05/08)
-
- PbTe nanostructures: Microwave-assisted synthesis by using lead Schiff-base precursor, characterization and formation mechanism
-
Pure cubic phase lead telluride (PbTe) nanostructures have been produced by using a Schiff-base complex as a precursor in the presence of microwave irradiation. The Schiff base used as ligand was derived from salicylaldehyde and ethylenediamine. The Schiff-base complex was marked as [Pb(salen)]. In addition, the effect of the irradiation time and the type of reducing agent on the morphology and purity of the final products was investigated. The as-synthesized PbTe nanostructures were characterized extensively by techniques like X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The microwave formation mechanism of the PbTe nanostructures was studied by XRD patterns of the products. Although it was found that both ionic and atomic mechanisms could take place for the preparation of PbTe, the main steps were according to the atomic reaction process, which could occur between elemental Pb and Te.
- Ahmadian-Fard-Fini, Shahla,Salavati-Niasari, Masoud,Monfared, Azam,Mohandes, Fatemeh
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p. 778 - 788
(2013/09/02)
-
- An EQCM-D study of the influence of chloride on the lead anodic oxidation
-
The influence of chloride on the electrodeposition of lead films and their dissolution in anodic stripping voltammetric experiments was examined. Gold substrates were plated with lead films, and mass changes were monitored by using the electrochemical quartz crystal microbalance with dissipation factor (EQCM-D). The results showed that the amount of electrodeposited lead is slightly dependent on the chloride concentration. The charge/mass ratio data indicated the presence of Pb(I) and Pb(II) as a result of film dissolution, and the precipitation and deposition of PbCl2 onto the electrode surface. Scanning electron microscopy images revealed that the morphology of the lead film was strongly influenced by chloride present in the plating solution and that much rougher films were obtained in comparison with those obtained in the absence of chloride. The rate of the anodic dissolution was higher for lead films with higher surface areas, which lead to an increase in their stripping voltammetric currents.
- Salles, Maiara O.,Martins, Vitor L.,Torresi, Roberto M.,Bertotti, Mauro
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p. 347 - 352
(2012/11/06)
-
- Bismuth film electrode for stripping voltammetric measurement of sildenafil citrate
-
A simple and fast procedure for measuring low concentration of sildenafil citrate (SC), also known as Viagra, at the ex situ prepared bismuth film electrode (BiFE) is demonstrated. The BiFE was prepared ex situ on the surface of a glassy carbon substrate electrode and employed in adsorptive cathodic stripping voltammetric mode in 0.1 M acetate buffer solution (pH 4.5) in the presence of dissolved oxygen. Electroanalytical properties of the BiFE were studied and compared with the ex situ prepared mercury film electrode, lead film electrode and with bare glassy carbon electrode. The BiFE revealed a LoD (3σ) of 1.8 × 10-8 mol L-1 using 120 s accumulation time and good linear response in the examined concentration range of 1.0 × 10-7 to 1.0 × 10-6 mol L-1 SC with a correlation coefficient (R2) of 0.995 using short accumulation time of 30 s. The obtained very good repeatability of 1.5% (c = 1.0 × 10-6 mol L-1, n = 15) corroborated potential applicability of the BiFE for measuring SC, for example in pharmaceutical formulations. A successful preliminary study using constant current chronopotentiometric stripping mode has been also carried out.
- Sopha, Hanna,Hocevar, Samo B.,Pihlar, Boris,Ogorevc, Bozidar
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p. 274 - 277
(2012/02/14)
-
- Dispersion energy enforced dimerization of a cyclic disilylated plumbylene
-
By reaction of 1,4-dipotassio-1,1,4,4-tetrakis(trimethylsilyl) tetramethyltetrasilane with PbBr2 in the presence of triethylphosphine a base adduct of a cyclic disilylated plumbylene could be obtained. Phosphine abstraction with B(C6F5)3 led to formation of a base-free plumbylene dimer, which features an unexpected single donor-acceptor PbPb bond. The results of density functional computations at the M06-2X and B3LYP level of theory indicate that the dominating interactions which hold the plumbylene subunits together and which define its actual molecular structure are attracting van der Waals forces between the two large and polarizable plumbylene subunits.
- Arp, Henning,Baumgartner, Judith,Marschner, Christoph,Zark, Patrick,Mueller, Thomas
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p. 6409 - 6415
(2012/05/07)
-
- Dramatically enhanced cleavage of the C-C bond using an electrocatalytically coupled reaction
-
This paper describes a generalized approach for the selective electrocatalytic C-C bond splitting in aliphatic alcohols at low temperature in aqueous state, with ethanol as an example. We show that selective C-C bond cleavage, leading to carbon dioxide, is possible in high pH aqueous media at low overpotentials. This improved selectivity and activity is achieved using a solution-born co-catalyst based on Pb(IV) acetate, which controls the mode of the ethanol adsorption so as to facilitate direct activation of the C-C bond. The simultaneously formed under-potentially deposited (UPD) Pb and surface lead hydroxide change the functionality of the catalyst surface for efficient promotion of CO oxidation. The resulting catalyst retains an unprecedented ability to sustain the full oxidation reaction pathway on an extended time scale of hours as opposed to minutes without addition of Pb(IV) acetate.
- He, Qinggang,Shyam, Badri,MacOunova, Katerina,Krtil, Petr,Ramaker, David,Mukerjee, Sanjeev
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p. 8655 - 8661
(2012/06/29)
-
- Preparation, characterization, and theoretical analysis of group 14 element(I) dimers: A case study of magnesium(I) compounds as reducing agents in inorganic synthesis
-
A synthetic route to the new amidine (DipNH)(DipN)- C(C6H 4But-4) (ButisoH; Dip = C6H3Pr i 2-2,6) has been developed. Its deprotonation with either LiBun or KN(SiMe3)2 yields the amidinate complexes [M(Butiso)] (M = Li or K). Their reactions with group 14 element halides/pseudohalides afford the heteroleptic group 14 complexes [(Butiso)SiCl3], [(Butiso)ECl] (E = Ge or Sn), and [{(Butiso)- Pb(μ-O 3SCF3)(THF)}∞], all of which have been crystallographically characterized. In addition, the synthesis and spectroscopic characterization of the homoleptic complex [Pb(Butiso)2] is reported. Reductions of the heteroleptic complexes with a soluble magnesium(I) dimer, [{(MesNacnac)Mg}2] (MesNacnac = [(MesNCMe) 2CH]; Mes = mesityl), have given moderate-to-high yields of the group 14 element(I) dimers [{(Butiso)E}2] (E = Si, Ge, or Sn), the X-ray crystallographic studies of which reveal trans-bent structures. The corresponding lead(I) complex could not be prepared. Comprehensive spectroscopic and theoretical analyses of [{(Butiso)E}2] have allowed their properties to be compared. All complexes possess E-E single bonds and can be considered as intramolecularly base-stabilized examples of ditetrelynes, REER. Taken as a whole, this study highlights the synthetic utility of soluble and easy to prepare magnesium(I) dimers as valuable alternatives to the harsh, and often insoluble, alkali-metal reducing agents that are currently widely employed in the synthesis of low-oxidation-state organometallic/inorganic complexes. 2011 American Chemical Society.
- Jones, Cameron,Bonyhady, Simon J.,Holzmann, Nicole,Frenking, Gernot,Stasch, Andreas
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p. 12315 - 12325
(2012/01/31)
-
- Mysteries of TOPSe revealed: Insights into quantum dot nucleation
-
We have investigated the reaction mechanism responsible for QD nucleation using optical absorption and nuclear magnetic resonance spectroscopies. For typical II-VI and IV-VI quantum dot (QD) syntheses, pure tertiary phosphine selenide sources (e.g., trioctylphosphine selenide (TOPSe)) were surprisingly found to be unreactive with metal carboxylates and incapable of yielding QDs. Rather, small quantities of secondary phosphines, which are impurities in tertiary phosphines, are entirely responsible for the nucleation of QDs; their low concentrations account for poor synthetic conversion yields. QD yields increase to nearly quantitative levels when replacing TOPSe with a stoiciometric amount of a secondary phosphine chalcogenide such as diphenylphosphine selenide. Based on our observations, we have proposed potential monomer identities, reaction pathways, and transition states and believe this mechanism to be universal to all II-VI and IV-VI QDs synthesized using phosphine based methods.
- Evans, Christopher M.,Evans, Meagan E.,Krauss, Todd D.
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p. 10973 - 10975
(2010/09/17)
-
- A new stable monomeric lead(ii) dithiolate Pb(SCH2CH 2NMe2)2: An interplay between a dynamic flip-flop process in solution and conformational isomerism in the solid-state
-
The structure and dynamic behaviour of monomeric lead(ii) dithiolate Pb(SCH2CH2NMe2)2 are studied by multi-nuclear NMR, IR and Raman spectroscopy in solution, as well as variable-temperature Raman spectroscopy and X-ray diffraction analysis in the solid-state, revealing an unusual dynamic flip-flop process in solution and reversible conformational isomerism of the chelated five-membered rings in the solid-state.
- Khrustalev, Victor N.,Aysin, Rinat R.,Borisova, Irina V.,Peregudov, Alexander S.,Leites, Larissa A.,Zemlyansky, Nikolai N.
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p. 9480 - 9483
(2011/01/08)
-
- Behavior of electrodeposited cd and pb schottky junctions on C H3 -Terminated n-Si(111) Surfaces
-
n-SiCd and n-SiPb Schottky junctions have been prepared by electrodeposition of Cd or Pb from acidic aqueous solutions onto H-terminated and C H3 -terminated n-type Si(111) surfaces. For both nondegenerately (n-) and degenerately (n+ -) doped H-Si(111) el
- Maldonado, Stephen,Lewis, Nathan S.
-
p. H123-H128
(2009/04/13)
-
- Electrocrystallization of Pb and Pb assisted Al on aluminum electrode from molten salt (AlCl3-NaCl-KCl)
-
Electrochemical deposition of aluminum and lead from basic molten AlCl3-NaCl-KCl mixture on an aluminum electrode at 180 °C was studied by the methods of voltammetry, potential and current transient and constant current deposition. The depositi
- Jafarian,Danaee,Maleki,Gobal,Mahjani
-
-
- Acyclic dialkylstannylene and -plumbylene compounds that are monomeric in the solid state
-
The new phosphine-borane adduct (Me2PhSi)CH2P(BH 3)Me2 is prepared by the reaction between Me 2PhSiCl and in situ-generated Me2P(BH3)CH 2Li; the adduct undergoes clean
- Izod, Keith,Wills, Corinne,Clegg, William,Harrington, Ross W.
-
p. 5661 - 5668
(2010/01/06)
-
- Kinetics of mechanochemical synthesis of Me/FeS (Me = Cu, Pb, Sb) nanoparticles
-
The mechanochemical synthesis of Cu/FeS, Pb/FeS and Sb/FeS nanoparticles was investigated with the regard to solid-state kinetics. Experiments were performed in a planetary mill and in an eccentric vibratory mill by a high-energy milling of Cu2
- Balá?,Dutková,?korvánek,Gock,Kovac,Satka
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p. 484 - 487
(2010/03/01)
-
- Agostic-type B - H...Pb interactions stabilize a dialkylplumbylene. Structure of and bonding in [{nPr2P(BH3)}(Me 3Si)C(CH2)]2Pb
-
The reaction between Cp2Pb and 1 equiv of [[{nPr 2P(BH3)] (Me3Si)C(CH2)]Li(THF) 2]2 in toluene affords the dialkylplumbylene [{nPr 2P(BH3)}(Me3Si)C(CH2)] 2Pb (10) in excellent yield; compound 10 may readily be separated into its two diastereomeric forms by a simple crystallization procedure. X-ray crystallography shows that rac- and meso-10 crystallize as discrete dialkylplumbylenes in which there are either two (rac-10) or one (meso-10) short agostic-type B - H...Pb contacts; for meso-10 there is a secondary, weak B - H...Pb contact, which affords this diastereomer a further, weak stabilization. Multielement and variable-temperature NMR studies indicate that, while rac-10 is essentially static in solution, meso10 undergoes dynamic exchange between the free and bound BH3 groups. Unusually, the methylene backbone protons in both diastereomers (at low temperature for meso-10) lic within the range 2.5-6.5 ppm, possibly due to the close proximity of the 6s lone pair on the lead center. DFT studies indicate that there is significant delocalization of B - H σ-bonding electron density into the vacant lead 6p orbital, furnishing an overall stabilization of 40.6 and 30.3 kcal mol-1 for rac- and meso-10, respectively.
- Izod, Keith,McFarlane, William,Wills, Corinne,Clegg, William,Harrington, Ross W.
-
p. 4386 - 4394
(2009/02/06)
-
- Tungsten-mediated activation of a PbII-N bond: A new route to tungsten-lead triple bonds
-
A W≡Pb bond is present in the hydrido plumbylidyne complex trans-[H-(PMe3)4W≡Pb(2,6-Trip2C 6H3)], which is formed by an unprecedented Pb-N activation reaction of {Pb(2,6-Trip2C6H3)-NMe 2}2, the first structurally characterized organolead(II) amide (see picture for molecular structure). Trip=2,4,6-iPr3C 6H2. (Chemical Equation Presented).
- Filippou, Alexander C.,Weidemann, Nils,Schnakenburg, Gregor
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p. 5799 - 5802
(2009/03/11)
-
- Persistent radicals of trivalent tin and lead
-
In this report we present synthetic, crystallographic, and new electron paramagnetic resonance (EPR) spectroscopic work that shows that the synthetic route leading to the recently reported, first persistent plumbyl radical ?PbEbt3 (Ebt = ethylbis(trimethylsilyl)silyl), that is, the oxidation of the related PbEbt3-anion, was easily extended to the synthesis of other persistent molecular mononuclear radicals of lead and tin. At first, various novel solvates of homoleptic potassium metallates KSnHyp 3 (4a), KPbHyp3 (3a), KSnEbt3 (4b), KPblDt 3 (3c), and KSnlbt3 (4c) (Hyp = tris(trimethylsilyl)silyl, lbt = isopropylbis(trimethylsilyl)silyl), as well as some heteroleptic metallates, such as [Li(OEt2)2][SnnBuHyp 2] (3d), [Li(OEt2)2][PbnBuHyp 2] (4d), [Li(thf)4][PbPhHyp2] (3e), and [K(thf)7][PbHyp2{N(SiMe3)2}] (3f), were synthesized and crystallographically characterized. Through oxidation by tin(II) and lead(II) bis(trimethylsilyl)amides or the related 2,6-di-tert-butylphenoxides, they had been oxidized to yield in most cases the corresponding radicals. Five novel persistent homoleptically substituted radicals, that is, ?SnHyp3 (2a), ?PbHyp3 (1a), ?SnEbt3 (2b), ?Snlbt3 (2c), and ?Pblbt 3 (1c), had been characterized by EPR spectroscopy. The stannyl radicals 2a and 2c as well as the plumbyl radical 1c were isolated as intensely colored crystalline compounds and had been characterized by X-ray diffraction. Persistent heteroleptically substituted radicals such as ?PbHyp 2Ph (1e) or ?PbHyp2Et (1g) had also been generated, and some selected EPR data are given for comparison. The plumbyl radicals ?PbR3 exhibit a clean monomolecular decay leading to the release of a temperature-dependent stationary concentration of branched silyl radicals. They may thus serve as tunable sources of these reactive species that may be utilized as reagents for mild radical silylations and/or as initiators for radical polymerizations. We present EPR-spectroscopic investigations for the new tin- and lead-containing compounds giving detailed insights into their electronic and geometric structure in solution, as well as structural studies on the crystalline state of the radicals, some of their anionic precursors, and some side-products.
- Becker, Marco,Foerster, Christoph,Franzen, Christian,Hartrath, Johannes,Kirsten, Enzio,Knuth, Joern,Klinkhammer, Karl W.,Sharma, Ajay,Hinderberger, Dariush
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p. 9965 - 9978
(2009/04/25)
-
- Thermal analysis of beaverite in comparisonwith plumbojarosite
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The thermal decomposition of beaverite and plumbojarosite was studied using a combination of thermogravimetric analysis coupled to a mass spectrometer. The mineral beaverite Pb(Fe,Cu)3(SO4)2(OH) 6 decomposes in three stages attributed to dehydroxylation, loss of sulphate and loss of oxygen, which take place at 376 and 420, 539 and 844°C. In comparison three thermal decomposition steps are observed for plumbojarosite PbFe6(SO4)4(OH)12 at 376, 420 and 502°C attributed to dehydroxylation; loss of sulphate occurs at 599°C; and loss of oxygen and formation of lead occurs at 844 and 953°C. The temperatures of the thermal decomposition of the natural plumbojarosite were found to be less than that for the synthetic jarosite. A comparison of the thermal decomposition of plumbojarosite with argentojarosite is made. The understanding of the chemistry of the thermal decomposition of minerals such as beaverite, argentojarosite and plumbojarosite and related minerals is of vital importance in the study known as 'archeochemistry'.
- Frost,Locke,Martens
-
p. 887 - 892
(2009/02/01)
-
- A comparison between chemical and sputtering methods for preparing thin-film silver electrodes for in situ ATR-SEIRAS studies
-
Stable silver thin films were prepared either by chemical deposition or by argon sputtering on germanium and silicon substrates, respectively, and used as electrodes for in situ infrared spectroscopy experiments with a Kretschmann internal reflection configuration. The spectra obtained for acetate anions adsorbed from neutral solutions showed a noticeable intensity enhancement (SEIRA effect). This enhanced absorption has been related to the surface structure of the films that have been characterized by ex situ STM and in situ electrochemical measurements (lead underpotential deposition, UPD). STM images of the chemically deposited silver films show mean grain sizes ranging from ca. 20 to 90 nm for deposition times between 2 and 20 min, and the absence of flat domains. On the other hand, STM images of the films deposited by argon sputtering show mean grain sizes around 30 nm for a film growth rate of 0.05 nm s-1 and 70 nm for a film growth rate of 0.005 nm s-1. In this latter case, atomically flat domains up to 50 nm wide have been observed. This observation is consistent with a more defined voltammetric profile for lead UPD, that indicates a higher degree of surface order. Moreover, the roughness factor obtained from the charge density involved in lead UPD in the case of the sputtered silver film is lower than that measured for the chemically deposited silver film. All these structural data can be connected with the observations on the effect of deposition conditions of the silver film on the SEIRA effect for adsorbed acetate. Maximum enhancement is observed for chemically deposited films and sputtered films at high deposition rate for which the grain size is around 40-60 nm. The increase of the grain size for the sputtered silver films deposited at decreasing deposition rates can be related to the observed decrease in the SEIRA effect.
- Delgado, José Manuel,Orts, José Manuel,Rodes, Antonio
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p. 4605 - 4613
(2008/10/09)
-
- Mechanochemical effects in redox reactions with participation of iron
-
The processes of deposition of copper, silver, and lead from their aqueous solutions separately on the concave (contracted) and convex (stretched) sides of a bent steel plate have been investigated. The difference in the deposition rate on the opposite sides gives evidence of the existence of the mechanochemical strain sign effect in redox reactions with the participation of iron. Nauka/Interperiodica 2007.
- Movchan,Rusanov
-
p. 398 - 403
(2008/03/11)
-
- Seeded growth fabrication of Cu-on-Si electrodes for in situ ATR-SEIRAS applications
-
A seeded-growth approach has been developed to fabricate a Cu nanoparticle film (simplified hereafter with nanofilm) on Si for electrochemical ATR surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS). The approach comprises an initial activation of the reflecting plane of hemicylindrical Si prism by introducing a Cu seed layer in a CuSO4-HF solution and the subsequent electroless deposition of the Cu nanofilms from an electroless Cu plating bath. The as-deposited Cu nanofilm exhibited strong SEIRA effect for the CO probe and interfacial free H2O. ATR-SEIRAS was also applied to characterize the adsorbed geometries of pyridine at the Cu/electrolyte interface. Only vibrational bands assignable to the A1 symmetry modes were detected in the entire potential window investigated, suggestive of an end-on adsorption via the ring N-atom on a Cu electrode.
- Wang, Hui-Feng,Yan, Yan-Gang,Huo, Sheng-Juan,Cai, Wen-Bin,Xu, Qun-Jie,Osawa, Masatoshi
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p. 5950 - 5957
(2008/10/09)
-
- Low-temperature heat capacity and thermodynamic properties of crystalline lead formate
-
As one 3-D coordination polymer, lead formate was synthesized; calorimetric study and thermal analysis for this compound were performed. The low-temperature heat capacity of lead formate was measured by a precise automated adiabatic calorimeter over the temperature range from 80 to 380 K. No thermal anomaly or phase transition was observed in this temperature range. A four-step sequential thermal decomposition mechanism for the lead formate was found through the DSC and TG-DTG techniques at the temperature range from 500 to 635 K.
- Zhang,Liu,Zhang,Lv,Sun,Xu,Tan,Zhang,Sawada
-
p. 643 - 647
(2008/10/09)
-
- On the mechanism of lead chalcogenide nanocrystal formation
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On the basis of evidence from 31P NMR spectroscopy, and using PbSe as a model, we propose two simultaneous mechanisms through which monomers are formed in preparations of lead chalcogenide nanocrystals (NCs). In one mechanism, selenium is delivered as a Se2- species, whereas in the other, Se0 reacts with metal already reduced by the organophosphine. This latter mechanism helps explain the sensitivity of NC preparations to the purity of organophosphines and allows the rational modification of batch NC reactions to increase yield. Copyright
- Steckel, Jonathan S.,Yen, Brian K. H.,Oertel, David C.,Bawendi, Moungi G.
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p. 13032 - 13033
(2008/02/05)
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- Epitaxial growth of Ag on Au(111) by galvanic displacement of Pb and Tl monolayers
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The development of a new method for epitaxial growth of metals in solution by galvanic displacement of layers predeposited by underpotential deposition (UPD) is discussed and experimentally illustrated. Cyclic voltammetry and scanning tunneling microscopy are employed to carry out and monitor a quasi-perfect, two-dimensional growth of up to 35 monolayers of Ag on Au(111) by repetitive galvanic displacement of underpotentially deposited Tl and Pb monolayers. A complementary kinetic study of Pb and Tl UPD layer stability at open-circuit potential identifies the oxygen reduction reaction and hydrogen evolution reaction as key oxidative competitors of Ag in the proposed displacement protocol. Analysis of the morphology evolution during the growth of Ag by displacement Pb and Tl UPD layers suggests the one-to-one exchange scenario (Ag-Tl) as more efficient for longer maintenance of a layer-by-layer silver deposition. The excellent quality of layers deposited by monolayer-restricted galvanic displacement is manifested by a steady UPD voltammetry and ascertained by an overall flat and uniform surface morphology maintained during the entire growth process. An X-ray photoelectron spectroscopy analysis finds no traces of Pb and Tl in the Ag deposit.
- Vasilic,Viyannalage,Dimitrov
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p. C648-C655
(2008/10/09)
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- Regularities of the formation of the photolysis products in the lead azide-cadmium system
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Compared to PbN6(Ab), the PbN6(Ab)-Cd system was found to be characterized by a low photolysis rate within the region of intrinsic absorption of PbN6(Ab) and, at the same time, by a broader range of spectral sensitivity of PbN6(Ab), up to 510 nm. Preliminary irradiation by 380-nm light resulted in an increase in the photolysis rate. The photolysis rate constants for the PbN6(Ab)-Cd system were determined. An analysis of the voltammetric characteristics, photocurrent, and contact potential difference made it possible to develop a model of the photolysis of the PbN6(Ab)-Cd system, including the stages of generation, recombination, redistribution of nonequilibrium charge carriers in the contact field, the photoemission of electrons, formation of the photolysis products, and genesis of the PbN6(Ab)-Pb(photolysis product)-Cd system. It was demonstrated that the diffusion of anionic vacancies to neutral Pb n 0 sites is the limiting stage of the photolysis of the PbN 6(Ab)-Cd system. Nauka/Interperiodica 2006.
- Surovoi,Bugerko,Rasmatova
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p. 1151 - 1155
(2007/10/03)
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- Effect of drying temperature on structure, phase transformation of sol-gel-derived lead zirconate titanate powders
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Lead zirconate titanate (PZT) (53/47) powders were prepared by a cheating acetate sol-gel process. The drying temperature effect on crystallization behavior was conducted to determine the best conditions for preparing high content of perovskite PZT powders in the morphotropic region. DSC/TG analysis, FT-IR spectrum and X-ray diffraction were carried out to identify the reaction sequences and calculated the activation energy of every transition temperature during the drying procedures. In the present work, well-crystallized, single-phase perovskite PZT powders were obtained after drying PZT stock solution at 300 °C for 1 h, then heat treatment at 600 °C for 30 min. The dependence of this crystallization temperature on the drying conditions was discussed.
- Chang, Tien-I,Huang, Jow-Lay,Lin, Hong-Ping,Wang, Sheng-Chang,Lu, Horng-Hwa,Wu, Long,Lin, Jen-Fu
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p. 224 - 229
(2008/10/09)
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- Lead electrodeposition from very alkaline media
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The electrodeposition of lead from very alkaline media has been studied by cyclic voltammetry, chronoamperometry under stationary and convective conditions. Experimental parameters like lead concentration and temperature have been varied. From NaOH 6 M the metal deposition takes place at about -0.90 V versus SCE far from the hydrogen evolution reaction (HER) which is seen at -1.30 V, but both processes are favoured by the lead content increase and the NaOH concentration decrease. The analyses of the chronoamperometric responses support the view of a 3D growth and suggest a substantial influence of lead concentration on the type of nucleation. Progressive nucleation is observed for the deposition from solutions with low content in lead but as this concentration increases a tendency towards instantaneous nucleation is revealed. The voltammetry with the rotating platinum disc electrode has confirmed that the lead electrodeposition is a mass transfer controlled process, and also allowed the estimation of diffusion coefficients.
- Wong, Sheila M.,Abrantes, Luísa M.
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p. 619 - 626
(2008/10/09)
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- Kinetics of the formation of photolysis products in the lead azide-cadmium telluride systems
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The kinetic and spectral regularities of the formation of the gaseous (nitrogen) and solid-phase (lead) products of the photolysis of lead azide in contact with cadmium telluride at different intensities of the incident light with λ = 380 nm were investigated by mass spectrometry and spectrophotometry. Rate constants of the photolysis of PbN6(Ab)-CdTe systems were determined. It was shown that, during the formation of PbN 6(Ab)-CdTe systems, the photolysis rate in the absorption region of PbN6(Ab) is decreased, and the region of spectral sensitivity of lead azide is broadened. Based on a consideration of measured current-voltage characteristics, photocurrent and photo-emf values, and contact potential differences, a model of the photolysis of PbN6(Ab)-CdTe systems was proposed. The model involves the stages of generation, recombination, and redistribution of nonequilibrium carriers in the contact field, formation of the photolysis products, and also formation of PbN6(Ab)-Pb (photolysis product)-CdTe heterogeneous systems. Copyright
- Surovoi,Bugerko,Rasmatova
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p. 981 - 985
(2007/10/03)
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- Effect of metals on silver electrodeposition: Application to the detection of cisplatin
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In the present work, the influence of several metals (Co, Ru, Pd, Os, Pt, Cu, Pb), deposited on a carbon paste electrode, towards silver electrodeposition was tested. First, adequate conditions for the electrodeposition of metals on the electrode were found. Then, the cyclic voltammograms registered (silver deposition curves and analytical signals) showed that Co, Cu, Pt and Pd were able to accelerate silver electrodeposition. Finally, a valid methodology for the detection of cisplatin was established. It is based on the deposition of silver on a Pt (from cisplatin) modified electrode and the analytical signal corresponds to the anodic stripping of the deposited silver. A limit of detection of 3.2 × 10-9 mol dm-3 (1 ng cm -3) cisplatin was obtained.
- Hernández-Santos, David,González-García, María Bego?a,Costa-García, Agustín
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p. 1895 - 1902
(2008/10/09)
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