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General chemistry, physical chemistry, Chimie générale, chimie physique, Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Electrochimie, Electrochemistry, Généralités, General, Sciences appliquees, Applied sciences, Electrotechnique. Electroenergetique, Electrical engineering. Electrical power engineering, Electroénergétique, Electrical power engineering, Conversion directe et accumulation d'énergie, Direct energy conversion and energy accumulation, Conversion électrochimique: piles et accumulateurs électrochimiques, piles à combustibles, Electrochemical conversion: primary and secondary batteries, fuel cells, Accumulateur électrochimique, Secondary cell, Acumulador electroquímico, Caractéristique électrique, Electrical characteristic, Característica eléctrica, Cobalt Oxyde, Cobalt Oxides, Cobalto Óxido, Couche oxyde, Oxide layer, Capa óxido, Cyclage, Cycling, Ciclaje, Imprégnation, Impregnation, Impregnación, Lithium Oxyde, Lithium Oxides, Litio Óxido, Magnésie, Magnesia, Magnésium Oxyde, Magnesium Oxides, Magnesio Óxido, Manganèse Oxyde, Manganese Oxides, Manganeso Óxido, Nickel Oxyde, Nickel Oxides, Niquel Óxido, Stabilité, Stability, Estabilidad, Traitement surface, Surface treatment, Tratamiento superficie, Batterie lithium ion, Lithion ion batteries, Li-rich lithium nickel cobalt manganese oxide, Lithium ion battery, Magnesium oxide layer, and Melting impregnation method

MgO-coated Li[Li0.2Mn0.54Ni0.13Co0.13]O2 was synthesized via melting impregnation method followed by a solid state reaction. Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) show that the MgO layer is well coated on the surface of the layered oxide particles. Although the initial discharge capacity of Li[Li0.2Mn0.54Ni0.13Co0.13]O2 with proper MgO modification decreases compared to the bare one, the 2 wt.% MgO coated cathode exhibits the excellent cycling stability with capacity retention of 96.4% at a current density of 200 mA g―1 after 100 cycles at room temperature and 94.3% after 50 cycles at 60 C. Electrochemical impedance spectroscopy (EIS) shows that the thin MgO layer mainly reduces the charge transfer resistance and stabilizes the surface structure of active material during cycling. Melting impregnation method is promising for MgO coating to improving the cycling stability of Li-rich layered oxide cathode for Li-ion batteries.

General chemistry, physical chemistry, Chimie générale, chimie physique, Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Electrochimie, Electrochemistry, Généralités, General, Métal transition, Transition metal, Metal transición, Platinoïde, Platinoid, Platinoide, Activité catalytique, Catalyst activity, Actividad catalítica, Alcool, Alcohol, Argent, Silver, Plata, Electrocatalyse, Electrocatalysis, Electrocatálisis, Electrode, Electrodes, Electrodo, Oxydation, Oxidation, Oxidación, Palladium, Paladio, Réaction électrochimique, Electrochemical reaction, Reacción electroquímica, Solution basique, Basic solution, Solución básica, Traitement surface, Surface treatment, Tratamiento superficie, Allyl alcohol, Electrocatalytic activity, Pd electrode, and Surface modification

The surface modification of Pd polycrystalline electrodes with silver and the electrocatalytic oxidation of allyl alcohol on Ag-modified Pd electrodes in alkaline solution have been investigated. Ag-modified Pd electrodes with different silver loadings were prepared by means of potentiostatic deposition of silver. Scanning electron microscope images demonstrate that Ag particles and cloud-like clusters of different sizes and shapes are formed on the Pd substrate, indicating three-dimensional deposition of silver, and that a large part of the Pd substrate is not covered by silver. The results of cyclic voltammetric measurement display that allyl alcohol oxidation on the Ag-modified Pd electrodes shows a slight negative shift in peak potential and a significant variation in peak current compared to those on Pd electrode. The peak current on the Ag-modified Pd electrodes is closely related to the amount of the deposited silver, much higher peak current than that on Pd electrode can be obtained. The results of chronoamperometric measurement show enhanced anti-poisoning ability of the Ag-modified Pd electrodes. Silver modification is found to be an effective method to improve electrocatalytic activity and stability of Pd electrode for allyl alcohol oxidation.

General chemistry, physical chemistry, Chimie générale, chimie physique, Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Electrochimie, Electrochemistry, Généralités, General, Sciences appliquees, Applied sciences, Energie, Energy, Energie naturelle, Natural energy, Energie solaire, Solar energy, Conversion photovoltaïque, Photovoltaic conversion, Cellules solaires. Cellules photoélectrochimiques, Solar cells. Photoelectrochemical cells, Cellule solaire, Solar cell, Célula solar, Couche barrière, Barrier layer, Performance, Rendimiento, Point quantique, Quantum dot, Punto cuántico, Recombinaison porteur charge, Charge carrier recombination, Recombinación portador carga, Réaction électrochimique, Electrochemical reaction, Reacción electroquímica, Réduction chimique, Chemical reduction, Reducción química, Traitement surface, Surface treatment, Tratamiento superficie, Quantum dot-sensitized solar cell, Si quantum dot, and Surface modification

Multiple exciton generation solar cell based on quantum dots has higher theoretical efficiency than single exciton generation solar cell. In this work, Si quantum dots with the diameter of 10 nm were fabricated by the multi-hollowdischarge plasma chemical vapor deposition and applied to the quantum dot-sensitized solar cell. In this cell, there was considerable electron recombination with redox electrolyte in the Si―TiO2 network because of large Si particle size. For the reduction of recombination and the enhancement of performance, a barrier layer was introduced. Zinc nitrate hexahydrate (Zn(NO3)2·6H2O) and zinc acetate dihydrate (Zn(CH3COO)2 H2O) were employed as precursors for surface modification. Consequently, short circuit current and open circuit voltage of the cells were increased by the surface modification with both precursors. The improvement was ascribed to the inhibition of electrons back transfer from TiO2 to the electrolyte by the barrier layer. This result clearly demonstrated that the surface modification with ZnO was advantageous for the performance enhancement.

General chemistry, physical chemistry, Chimie générale, chimie physique, Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Electrochimie, Electrochemistry, Généralités, General, Bipolaire, Bipolar, Germanium, Germanio, Gravure électrochimique, Electrochemical etching, Grabado electroquímico, Matériau poreux, Porous material, Material poroso, Mésoporosité, Mesoporosity, Mesoporosidad, Propriété physicochimique, Physicochemical properties, Propiedad fisicoquímica, Traitement surface, Surface treatment, Tratamiento superficie, Bipolar electrochemical etching, Mesoporous materials, and Porous Germanium

The formation of mesoporous Ge layers with different morphologies by bipolar electrochemical etching is reported for the first time. A detailed analysis of the effect of anodic/cathodic pulse duration on the mesoporous Ge formation is performed. It is shown that together with the applied current density and anodization time this parameter has the most important influence on porous Ge morphology. Six different types of porous morphologies were identified with the nanopore diameter being in the range from 5 to 15 nm. Their crystalline nature has been confirmed by Raman spectroscopy. The diameters of the nanocrystallites of the porous Ge layers were extracted from Raman spectra by using the phononconfinement model. Depending of the layer morphology their values varied between 4 and 10 nm). A conceptual analysis of several aspects of the formation mechanisms of mesoporous Germanium based on the available information has allowed us to predict and create a new complex morphology.

General chemistry, physical chemistry, Chimie générale, chimie physique, Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Electrochimie, Electrochemistry, Electrodes: préparations et propriétés, Electrodes: preparations and properties, Autres électrodes, Other electrodes, Carbone, Carbon, Carbono, Diamant, Diamond, Diamante, Electrode, Electrodes, Electrodo, Etat vitreux, Glassy state, Estado vitreo, Matériau modifié, Modified material, Material modificado, Microscopie électronique transmission, Transmission electron microscopy, Microscopía electrónica transmisión, Morphologie, Morphology, Morfología, Nanomatériau, Nanostructured materials, Particule ultrafine, Ultrafine particle, Partícula ultrafina, Recuit thermique, Thermal annealing, Recocido térmico, Spectrométrie IR, Infrared spectrometry, Espectrometría IR, Spectrométrie Raman, Raman spectrometry, Espectrometría Raman, Spectrométrie impédance électrochimique, Electrochemical impedance spectroscopy, Structure surface, Surface structure, Estructura superficie, Traitement surface, Surface treatment, Tratamiento superficie, Traitement thermique, Heat treatment, Tratamiento térmico, Transformation Fourier, Fourier transformation, Transformación Fourier, FT IR, Annealing, Electrochemical activity, Nanodiamond, and Surface modification

Surface modifications of undoped nanodiamond (ND) particles were carried out through different annealing treatments. The methods of Fourier transform infrared spectroscopy, Raman spectroscopy, and transmission electron microscopy were used to characterize the ND surface before and after the annealing process. The electrochemical properties of the modified ND powders in aqueous solution were investigated with Fe(CN)63―/4― as a redox probe. When the annealing temperature was below 850°C, vacuum annealing removed parts of the oxygen-containing surface functionalities from the ND surface and produced more sp2 carbon atoms in the shell. The charge transfer of the Fe(CN)63―/4― redox couple decreased with increasing annealing temperature. Re-annealing in air restored the original surface conditions: few sp2-bonded carbon atoms and similar surface functionalities, and thus the electrochemical activity. When ND was annealed in vacuum at 900―1100°C, more serious graphitization produced a continuous fullerenic shell wrapped around a diamond core, which had a high conductivity and electrochemical activity. This provides a novel nanoparticle with high conductivity and high stability for electrochemical applications.

General chemistry, physical chemistry, Chimie générale, chimie physique, Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Electrochimie, Electrochemistry, Généralités, General, Antimoine Complexe, Antimony Complexes, Antimonio Complejo, Carbone, Carbon, Carbono, Complexe aqua, Aqua complex, Complejo aqua, Complexe hétéronucléaire, Heteronuclear complex, Complejo heteronuclear, Complexe oxo, Oxo complex, Complejo oxo, Complexe polynucléaire, Polynuclear complex, Complejo polinuclear, Composé sandwich, Sandwich compound, Compuesto sandwich, Couche autoassemblée, Self-assembled layer, Capa autoensamblada, Couche multimoléculaire mixte, Mixed multilayer, Capa multimolecular mixta, Couple redox, Redox couple, Pareja redox, Electrode, Electrodes, Electrodo, Fer Complexe, Iron Complexes, Hierro Complejo, Hétéropolysel, Heteropolysalt, Heteropolisal, Immobilisation, Immobilization, Inmovilización, Matériau modifié, Modified material, Material modificado, Oxalate, Oxalato, Peroxyde d'hydrogène, Hydrogen peroxide, Peróxido de hydrogeno, Polymère conducteur, Conducting polymers, Pyrrole polymère, Pyrrole polymer, Pirrol polímero, Réaction électrochimique, Electrochemical reaction, Reacción electroquímica, Réduction chimique, Chemical reduction, Reducción química, Sodium Composé, Sodium Compounds, Sodio Compuesto, Traitement surface, Surface treatment, Tratamiento superficie, Tungstène Complexe, Tungsten Complexes, Wolframio Complejo, Tungstoantimoniate, Conducting polymer, LBL, Polyoxometallate, and Sandwich type

A functionalised Fe-substituted Keggin Na14[Fe4(C2O4)4(H2O)2(SbW9O33)2]·60H2O type POM termed Fe4Ox4 has been successfully immobilised onto carbon electrode surfaces through the employment of conducting polypyrrole films and the layer-by-layer (LBL) technique. For the POM doped polypyrrole films the redox systems associated with the POM's tungsten-oxo framework was not apparent upon redox cycling, however a reversible redox couple associated with the FeIII/II redox system was clearly seen within the pH range 2-7. Organised multilayer assemblies were constructed by the employment of the layer by layer (LBL) technique through alternating anionic Fe4Ox4 layers and cationic RuII metallodendrimers with poly(diallyldimethylammonium chloride) (PDDA) employed as an initial base layer. Stable redox couples associated with both the FeIII/II and tungsten-oxo framework, for the Fe4Ox4 POM, and the RuIII/II for the metallodendrimer, were clearly observed upon layer construction and redox switching within the pH domain of 2-7. The resulting multilayer assembly showed good stability towards redox cycling. Further investigations into the multilayer assembly were undertaken by determining it is charge transfer resistance using AC-impedance voltammetry. The layer also showed catalytic ability towards the reduction of H2O2 at pH 6.5.

General chemistry, physical chemistry, Chimie générale, chimie physique, Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Energie, Energy, Energie naturelle, Natural energy, Energie solaire, Solar energy, Conversion photovoltaïque, Photovoltaic conversion, Cellules solaires. Cellules photoélectrochimiques, Solar cells. Photoelectrochemical cells, Additif, Additive, Aditivo, Cellule solaire à colorant, Dye-sensitized solar cell, Célula solar sensibilizada tinte, Conversion photovoltaïque, Photovoltaic conversion, Conversión fotovoltaica, Courant photoélectrique, Photoelectric current, Corriente fotoeléctrica, Effet structure, Structure effect, Efecto estructura, Ethylène oxyde polymère, Ethylene oxide polymer, Etileno óxido polímero, Matériau modifié, Modified material, Material modificado, Nanoparticule, Nanoparticle, Nanopartícula, Performance, Rendimiento, Photoélectrode, Photoelectrode, Fotoelectrodo, Titane IV Chlorure, Titanium IV Chlorides, Titanio IV Cloruro, Titane IV Oxyde, Titanium IV Oxides, Titanio IV Óxido, Traitement surface, Surface treatment, Tratamiento superficie, Dye-sensitized solar cells, Modification, and TiO2 films

Due to the complexity of dye-sensitized solar cell modules, the conversion efficiency increased slightly over the years of development. The TiO2 photoelectrode, as core part in the module, plays an important role in the overall performance. Here, we conducted series of associative experiments on modification of the TiO2 photoelectrode to achieve a better performance. The paste was prepared using conventional P-25 powder, and the conversion efficiency was found to be increased from the initial 1.41% to 2.48% by optimizing paste additives. Further, a merchandised paste with smaller particle size was introduced to fabricate a double-layer cell with the P-25 paste, followed by a surface treatment with TiCl4. The final result was observed to be quite satisfactory with a sharp increase in the conversion efficiency of 6.51%.

General chemistry, physical chemistry, Chimie générale, chimie physique, Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Electrochimie, Electrochemistry, Electrodes: préparations et propriétés, Electrodes: preparations and properties, Autres électrodes, Other electrodes, Acide fluorhydrique, Hydrofluoric acid, Ácido fluorhídrico, Acide sulfurique, Sulfuric acid, Sulfúrico ácido, Bore Composé, Boron Compounds, Boro Compuesto, Cinétique, Kinetics, Cinética, Composé du diazonium, Diazonium compounds, Diazonio compuesto, Composé nitro, Nitro compound, Compuesto nitro, Electrode, Electrodes, Electrodo, Greffage, Grafting, Injerto, Monocristal, Single crystal, Mécanisme réaction, Reaction mechanism, Mecanismo reacción, Orientation cristalline, Crystal orientation, Orientación cristalina, Réaction électrochimique, Electrochemical reaction, Reacción electroquímica, Réduction chimique, Chemical reduction, Reducción química, Semiconducteur type p, p type semiconductor, Semiconductor tipo p, Silicium, Silicon, Silicio, Solution acide, Acidic solution, Solución ácida, Solution aqueuse, Aqueous solution, Solución acuosa, Spectrométrie IR, Infrared spectrometry, Espectrometría IR, Spectrométrie impédance électrochimique, Electrochemical impedance spectroscopy, Traitement surface, Surface treatment, Tratamiento superficie, Transformation Fourier, Fourier transformation, Transformación Fourier, Voltammétrie, Voltammetry, Voltametría, Benzènediazonium(4-nitro) tétrafluoroborate, FT IR, 4-Nitrobenzene diazonium, Electrochemical reduction, Hydrogenated silicon surface, and tetrafluoroborate

The hydrogenated silicon surface has outstanding electronic properties. However, its resistance to oxidation is insufficient. An alternative is the substitution of the Si—H bonds with Si-organic groups. This modification of the silicon surface by grafting of organic molecules was carried out by electrochemical reduction of 4-nitrobenzene diazonium tetrafluoroborate in an aqueous medium containing HF and H2SO4. The choice fell on this electrochemical reaction because it allows for fast grafting. The reduction of nitrobenzene diazonium is confirmed by the presence of a voltammetric peak around -0.1 V/SCE. The grafting was also characterized by in situ infrared spectroscopy (FTIR) which, via the detection of vibrations characteristic of chemical bonds, allows one to identify the chemical functions present. In addition, electrochemical impedance measurements allowed us to approach the interfacial mechanisms. It appears that the cathodic grafting leads to the formation of a polymeric layer, but the same grafting also occurs spontaneously within a few tens of seconds at open circuit potential, an expected phenomenon indeed in view of the reduction potential of 4-nitrobenzene diazonium.

General chemistry, physical chemistry, Chimie générale, chimie physique, Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Electrochimie, Electrochemistry, Electrodes: préparations et propriétés, Electrodes: preparations and properties, Autres électrodes, Other electrodes, Acier inoxydable, Stainless steel, Acero inoxidable, Application, Aplicación, Carbone Nitrure, Carbon Nitrides, Carbono Nitruro, Couche mince, Thin film, Capa fina, Matériau électrode, Electrode material, Material electrodo, Prétraitement, Pretreatment, Pretratamiento, Spectrométrie impédance électrochimique, Electrochemical impedance spectroscopy, Traitement surface, Surface treatment, Tratamiento superficie, Traitement électrochimique, Electrochemical treatment, Tratamiento electroquímico, Carbon nitride, EIS, and Electrochemical reactivity

In this work, a-CNx films prepared by DC magnetron sputtering on stainless steel substrate have been investigated as electrode materials. While their wide potential window was confirmed as a property shared by boron doped diamond (BDD) electrodes, their electrochemical activity with respect to fast and reversible redox systems, [Ru(NH3)6]3+/2+, [Fe(CN)6]3―/4― and [IrCl6]2―/3―, was assessed by Electrochemical Impedance Spectroscopy (EIS) after cathodic or anodic electrochemical pre-treatments or for as grown samples. It was shown for the three systems that electrochemical reactivity of the a-CNx films was improved after the cathodic pre-treatment and degraded after the anodic one, the apparent heterogeneous rate constant k0app being decreased by at least one order of magnitude for the latter case. A high k0app value of 0.11 cm s―1 for [IrCl6]2―/3― was obtained, close to the highest values found for BDD electrodes.

General chemistry, physical chemistry, Chimie générale, chimie physique, Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Electrochimie, Electrochemistry, Généralités, General, Sciences appliquees, Applied sciences, Electrotechnique. Electroenergetique, Electrical engineering. Electrical power engineering, Electroénergétique, Electrical power engineering, Conversion directe et accumulation d'énergie, Direct energy conversion and energy accumulation, Conversion électrochimique: piles et accumulateurs électrochimiques, piles à combustibles, Electrochemical conversion: primary and secondary batteries, fuel cells, Metaux. Metallurgie, Metals. Metallurgy, Corrosion, Mécanismes fondamentaux et formes de la corrosion, Corrosion mechanisms, Accumulateur électrochimique, Secondary cell, Acumulador electroquímico, Elektrische Batterie, Anode, Anodo, Caractéristique électrique, Electrical characteristic, Característica eléctrica, Elektrische Groesse, Couche oxyde, Oxide layer, Capa óxido, Oxidschicht, Cyclage, Cycling, Ciclaje, Cycle charge décharge, Discharge charge cycle, Ciclo carga descarga, Dépôt chimique phase vapeur, Chemical vapor deposition, Depósito químico fase vapor, Chemisches Aufdampfen, Matière active, Active material, Materia activa, Matériau modifié, Modified material, Material modificado, Matériau électrode, Electrode material, Material electrodo, Microparticule, Microparticle, Micropartícula, Microscopie électronique transmission, Transmission electron microscopy, Microscopía electrónica transmisión, Transmissionselektronenmikroskopie, Morphologie, Morphology, Morfología, Plasma couplé inductivement, Inductively coupled plasma, Rayon X, X ray, Rayos X, Roentgenstrahlen, Silicium Oxyde, Silicon Oxides, Silicio Óxido, Silicium, Silicon, Silicio, Spectrométrie photoélectron, Photoelectron spectrometry, Espectrometría fotoelectrón, ESCA Spektrometrie, Structure surface, Surface structure, Estructura superficie, Oberflaechenbeschaffenheit, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Batterie lithium ion, Lithion ion batteries, ICP-CVD, Lithium-ion battery, Si particle, and Silicon oxidation number

The high capacity and optimal cycle characteristics of silicon render it essential in lithium-ion batteries. The authors have attempted to realize a composite material by coating individual silicon (Si) particles of a few micrometers in diameter with a silicon oxide film to serve as an active material in the anode and so optimize the charge-discharge characteristics of the lithium-ion battery. Particle coating was achieved using an inductively coupled plasma-chemical vapor deposition (ICP-CVD) process that realized a homogenous coating of silicon oxide film on each Si particle. The film was synthesized based on tetraethyl orthosilicate (TEOS), with hydrogen (H2)gas used as a reducing agent to deoxidize the silicon dioxide. This enabled the control of the silicon oxidation number in the layers produced by adjusting the H2 flow during the silicon oxidization deposition with ICP-CVD. The silicon oxide covering the Si particles included both silicon monoxide and suboxide, which served to optimize the charge-discharge characteristics. The authors have succeeded in realizing a favorable active material using Si which is abundant in nature in the anode of a lithium-ion battery with highly charged, optimized cycle properties.

General chemistry, physical chemistry, Chimie générale, chimie physique, Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Electrochimie, Electrochemistry, Electrodes: préparations et propriétés, Electrodes: preparations and properties, Autres électrodes, Other electrodes, Aminoacide, Aminoacid, Aminoácido, Carbone, Carbon, Carbono, Composé aliphatique, Aliphatic compound, Compuesto alifático, Composé aromatique, Aromatic compound, Compuesto aromático, Electrode, Electrodes, Electrodo, Etat vitreux, Glassy state, Estado vitreo, Etude théorique, Theoretical study, Estudio teórico, Fonctionnalisation, Functionalization, Funciónalización, Ion amphotère, Zwitterion, Ión anfotérico, Méthode fonctionnelle densité, Density functional method, Traitement surface, Surface treatment, Tratamiento superficie, Greffage électrochimique, Electrochemical grafting, Amino acid, DFT, Glassy carbon, Grafting, and Zwitterionic

Glassy carbon (GC) electrode surfaces are functionalized through electrochemical assisted grafting, in oxidation regime, of six amino acids (AA): β-alanine (β-Ala), L-aspartic acid (Asp), 11-aminoundecanoic acid (UA), 4-aminobenzoic acid (PABA), 4-(4-amino-phenyl)-butyric acid (PFB), 3-(4-amino-phenyl)-propionic acid (PFP). Thus, a GC/AA interface is produced featuring carboxylic groups facing the solution. Electrochemical (cyclic voltammetry and electrochemical impedance spectroscopy) and XPS techniques are used to experimentally characterize the grafting process and the surface state. The theoretical results are compared with the experimental evidence to determine, at a molecular level, the overall grafting mechanism. Ionization potentials, standard oxidation potentials, HOMO and electron spin distributions are calculated at the CCD/6-31G* level of the theory. The comparison of experimental and theoretical data suggests that the main electroactive species is the zwitterionic form for the three aliphatic amino acids, while the amino acids featuring the amino group bound to the phenyl aromatic moiety show a different behaviour. The comparison between experimental and theoretical results suggests that both the neutral and the zwitterionic forms are present in the acetonitrile solution in the case of 4-(4-amino-phenyl)-butyric acid (PFB) and 3-(4-amino-phenyl)-propionic acid.

General chemistry, physical chemistry, Chimie générale, chimie physique, Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Electrochimie, Electrochemistry, Electrodes: préparations et propriétés, Electrodes: preparations and properties, Autres électrodes, Other electrodes, Etude des interfaces, Study of interfaces, Dépôt électrolytique, Electrodeposition, Métal transition, Transition metal, Metal transición, Attaque chimique, Chemical etching, Ataque químico, Carbonate polymère, Polycarbonate, Carbonato polímero, Couple redox, Redox couple, Pareja redox, Dépôt électrolytique, Electrodeposition, Depósito electrolítico, Ion fer, Iron ion, Hierro ión, Membrane polymère, Polymeric membrane, Membrana polímero, Nanotube, Nanotubo, Or, Gold, Oro, Réaction électrochimique, Electrochemical reaction, Reacción electroquímica, Traitement surface, Surface treatment, Tratamiento superficie, Assemblage électrode, Electrode assembly, Nanoélectrode, Nanoelectrode, Synthèse sur matrice, Template synthesis, Controlled chemical etching, Electrodeposited gold nanotubes, Nanoelectrode ensembles, and Polycarbonate membranes

Electrodeposition of long and well-defined gold nanotubes in polycarbonate (PC) templates is still a major concern due to pore blockage problems. In the present study, we introduce a novel method for electrodeposition of long gold nanotubes within the pores of PC templates for the first time. In order to deposit gold atoms onto the pore walls preferentially, pore walls were functionalized with a coupling agent. Short and thin Ni nanotubes were then electrodeposited at the bottom of the pores. Gold nanotubes were subsequently electrodeposited at constant potentials and low solution concentrations. The morphology of nanotubes was characterized by electron microscopy and their formation mechanism was discussed in detail. Gold nanotubes were fabricated inside PC template with different lengths even as long as the template thickness which was about 6 μm. Using controlled chemical etching of PC template, three-dimensional gold nanoelectrode ensembles (3D GNEs) were developed which show much higher sensitivity compared to their embedded GNEs counterparts in the presence of Fe2+/Fe3+ redox couple. Cyclic voltammograms show that the sensitivity of 3D GNEs increases with increasing the number of etching cycle.

General chemistry, physical chemistry, Chimie générale, chimie physique, Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Electrochimie, Electrochemistry, Généralités, General, Aluminate, Aluminates, Aluminato, Anion minéral, Inorganic anion, Anión inorgánico, Electrolyte, Electrólito, Etude comparative, Comparative study, Estudio comparativo, Matériau revêtement, Coating material, Material revestimiento, Oxydation, Oxidation, Oxidación, Réaction électrochimique, Electrochemical reaction, Reacción electroquímica, Silicate, Silicates, Silicato, Silicium Composé, Silicon Compounds, Silicio Compuesto, Traitement par plasma, Plasma assisted processing, Traitement surface, Surface treatment, Tratamiento superficie, Zirconium IV Oxyde, Zirconium IV Oxides, Zirconio IV Óxido, Zirconium alliage, Zirconium alloy, Zirconio aleación, Dry sliding test, Plasma electrolytic oxidation, Zirconium, and t-ZrO2

Plasma electrolytic oxidation of Zircaloy-2 at constant rms current is examined in silicate and aluminate electrolytes, revealing significantly different behaviors in the growth kinetics and properties of the coatings. Coatings thicken continuously in the silicate electrolyte, while in the aluminate electrolyte, the thickness reaches a relatively constant value. The latter coincides with changing appearances of discharges and detachment of an outer coating layer. Dissolution of zirconium is faster in the silicate electrolyte in the early stage of PEO, but is faster in the aluminate electrolyte following coating breakdown. The pre-spallation coating formed in the aluminate electrolyte shows superior wear resistance, which can be ascribed to its relative compactness, associated with the presence of tetragonal zirconia stabilized by aluminium species.

General chemistry, physical chemistry, Chimie générale, chimie physique, Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Electrotechnique. Electroenergetique, Electrical engineering. Electrical power engineering, Matériel électrique divers, Various equipment and components, Condensateurs. Résistances. Filtres, Capacitors. Resistors. Filters, Bois, Wood, Madera, Capacité spécifique, Specific capacity, Capacidad específica, Caractéristique électrique, Electrical characteristic, Característica eléctrica, Carbone, Carbon, Carbono, Condensateur électrochimique, Electrolytic capacitor, Condensador electroquímico, Distribution potentiel, Potential distribution, Distribución potencial, Double couche électrochimique, Electrochemical double layer, Doble capa electroquímica, Interface électrode électrolyte, Electrode electrolyte interface, Interfase electrodo electrolito, Matériau monolithique, Monolithic material, Material monolítico, Matériau poreux, Porous material, Material poroso, Microscopie électronique balayage, Scanning electron microscopy, Microscopía electrónica barrido, Morphologie, Morphology, Morfología, Performance, Rendimiento, Spectrométrie IR, Infrared spectrometry, Espectrometría IR, Structure surface, Surface structure, Estructura superficie, Supercondensateur, Supercapacitor, Supercondensador, Traitement surface, Surface treatment, Tratamiento superficie, Transformation Fourier, Fourier transformation, Transformación Fourier, FT IR, Carbon monolith, Electric double-layer capacitor, Porous wood carbon, Supercapacitors, and Surface modification

A surface modified porous wood carbon monolith (m-WCM) with high consistency and large porosity was successfully synthesized by carbonization of poplar wood and subsequent surface modification with HNO3 solution. The pore properties of obtained m-WCM, including the BET surface area, pore volume. and pore size distribution of these activated carbons were characterized by the N2 adsorption isotherms. The surface functional groups were characterized by Fourier transform infrared spectroscopy. Surface morphology and microstructure were physically characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The obtained m-WCM was studied as electrodes for supercapacitors and exhibited excellent electrochemical performance compared with typical activated carbon (AC) and ordered mesoporous carbon (CMK-3). The effects of modification conditions on supercapacitive behavior were systematically studied, a maximum gravimetric capacitance (Cm) and volumetric capacitance (Cv) of 234 F g―1 and 36 F cm―3 were obtained in 2 M KOH solution. Long-term cycling experiments showed excellent stability with a reduction of the initial capacitance values of 3% after performing 2000 galvanostatic cycles at 10 mA cm―2.

General chemistry, physical chemistry, Chimie générale, chimie physique, Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Electrochimie, Electrochemistry, Cinétique et mécanisme des réactions, Kinetics and mechanism of reactions, Sciences appliquees, Applied sciences, Physicochimie des polymeres, Physicochemistry of polymers, Polymères et rayonnements, Polymers and radiations, Polymérisation, Polymerization, Acétonitrile, Acetonitrile, Acetonitrilo, Brosse polymère, Polymer brush, Cepillo polímero, Carbone, Carbon, Carbono, Composé du diazonium, Diazonium compounds, Diazonio compuesto, Couche monomoléculaire, Monolayer, Capa monomolecular, Dérivé du thiophène, Thiophene derivatives, Tiofeno derivado, Electrode, Electrodes, Electrodo, Etat vitreux, Glassy state, Estado vitreo, Liaison covalente, Covalent bond, Enlace covalente, Matériau modifié, Modified material, Material modificado, Polymère conducteur, Conducting polymers, Polymérisation électrolytique, Electrochemical polymerization, Polimerización electrolítica, Rayon X, X ray, Rayos X, Réaction électrochimique, Electrochemical reaction, Reacción electroquímica, Solvant organique, Organic solvent, Solvente orgánico, Spectrométrie photoélectron, Photoelectron spectrometry, Espectrometría fotoelectrón, Thiophène dérivé polymère, Thiophene derivative polymer, Tiofeno derivado polímero, Traitement surface, Surface treatment, Tratamiento superficie, Ammonium(tétrabutyl) tétrafluoroborate, Aniline(thiényl), Ethylènedioxythiophène polymère, Greffage électrochimique, Electrochemical grafting, EDOT, Electrochemical reduction of diazonium, Molecule immobilization, Polymer brushes, Surface-initiated electropolymerization, and salts

The work describes the formation of poly(3,4-ethylenedioxythiophene) (PEDOT) brushes attached to thienyl-modified glassy carbon surface (GC) via surface-initiated electrochemical polymerization. The initial modification of the GC electrode was performed by using of three different thienyl-derivatives of aniline that were first converted to the form of diazonium salts. These salts were then electrochemically reduced creating the organic monolayer covalently bound to GC. The surface layer was investigated electrochemically and identified using XPS. The structural conjugation of the resulting monolayer made it possible to initiate the electrochemical polymerization of EDOT from the modified surface. The polymeric structure formed on the thienyl-modified surface reveals a better redox peak separation as compared to the classical polymer film on a bare electrode that can be assigned to its more ordered and uniform structure.

General chemistry, physical chemistry, Chimie générale, chimie physique, Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Electrochimie, Electrochemistry, Photoélectrochimie. Electrochimiluminescence, Photoelectrochemistry. Electrochemiluminescence, Alliage base magnésium, Magnesium base alloys, Anodisation, Anodizing, Anodización, Electroluminescence, Electroluminiscencia, Luminescence, Luminiscencia, Oxydation, Oxidation, Oxidación, Réaction électrochimique, Electrochemical reaction, Reacción electroquímica, Spectrométrie optique, Optical spectrometry, Espectrometría óptica, Spectrométrie émission, Emission spectrometry, Espectrometría emisión, Traitement par plasma, Plasma assisted processing, Traitement surface, Surface treatment, Tratamiento superficie, Anodization, Galvanoluminescence, Magnesium alloy AZ31, and Plasma electrolytic oxidation

In this paper, we have presented our recent investigation of luminescence during anodization of magnesium alloy AZ31 at 100 mA/cm2 in water solution containing 4g/L Na2SiO3·5H2O + 4 g/L KOH, Spectral characterization of anodic luminescence (galvanoluminescence GL) showed that there are wide GL bands in the range from 375 nm to 875 nm, with three spectral peaks around 430 nm, 600 nm and 780 nm. As the anodization voltage approaches the breakdown voltage, a large number of microdischarges appear superimposed on the GL. The microdischarges characteristics above breakdown (so-called plasma electrolytic oxidation PEO) were studied using real-time imaging. The spatial density of microdischarges is the highest in the early stage of PEO, while the percentage of oxide coating area covered by active discharge sites has maximum after about 120s from the beginning of PEO and then stays almost constant. The elements present in PEO microdischares were identified using optical emission spectroscopy technique.

General chemistry, physical chemistry, Chimie générale, chimie physique, Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Electrotechnique. Electroenergetique, Electrical engineering. Electrical power engineering, Electroénergétique, Electrical power engineering, Conversion directe et accumulation d'énergie, Direct energy conversion and energy accumulation, Conversion électrochimique: piles et accumulateurs électrochimiques, piles à combustibles, Electrochemical conversion: primary and secondary batteries, fuel cells, Accumulateur électrochimique, Secondary cell, Acumulador electroquímico, Carbone, Carbon, Carbono, Exfoliation, Exfoliación, Fonctionnalisation, Functionalization, Funciónalización, Insertion, Inserción, Interface électrode électrolyte, Electrode electrolyte interface, Interfase electrodo electrolito, Ion lithium, Lithium ion, Litio ión, Rayon X, X ray, Rayos X, Spectrométrie photoélectron, Photoelectron spectrometry, Espectrometría fotoelectrón, Traitement surface, Surface treatment, Tratamiento superficie, Batterie lithium ion, Lithion ion batteries, Carbon cloth, Lithium batteries, SEI formation, and Surface electrochemisty

Commercial carbon cloth made of PAN-based carbon fibres was used as free-standing anode for lithium intercalation. The role of surface functional groups on the specific irreversible charge loss and reversible charge during the intercalation and de-intercalation of lithium ions into carbon cloth has been investigated. Oxygen groups have been introduced by nitric acid vapour treatment and subsequently gradually removed by thermal treatment at different temperatures in He or H2 atmosphere as confirmed by X-ray photoelectron spectroscopy. A clear correlation between the amount of surface-bound oxygen groups and the irreversible specific charge was observed. Three irreversible processes were distinguished during the first cathodic scan: (i) reduction of oxygen groups, (ii) formation of the solid electrolyte interphase (SEI) and (iii) presumably exfoliation. The latter one was only observed for samples with low surface oxygen concentration, and its contribution to the irreversible capacity was small due to the low graphitization degree of the samples. An increased specific reversible charge upon increasing the amount of oxygen-containing groups was observed with the main improvement above 1.5 V.

General chemistry, physical chemistry, Chimie générale, chimie physique, Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Electrochimie, Electrochemistry, Electrodes: préparations et propriétés, Electrodes: preparations and properties, Autres électrodes, Other electrodes, Chimie analytique, Analytical chemistry, Méthodes électrochimiques, Electrochemical methods, Ampérométrie, Amperometry, Amperometría, Analyse chimique, Chemical analysis, Análisis químico, Carbone, Carbon, Carbono, Détecteur électrochimique, Electrochemical detector, Detector electroquímico, Electrocatalyse, Electrocatalysis, Electrocatálisis, Electrode, Electrodes, Electrodo, Etat vitreux, Glassy state, Estado vitreo, Fonctionnalisation, Functionalization, Funciónalización, Matériau modifié, Modified material, Material modificado, Microscopie électronique balayage, Scanning electron microscopy, Microscopía electrónica barrido, Morphologie, Morphology, Morfología, Nanotube carbone, Carbon nanotubes, Nanotube multifeuillet, Multiwalled nanotube, Nanotubo pared múltiple, Oxydation, Oxidation, Oxidación, Peroxyde d'hydrogène, Hydrogen peroxide, Peróxido de hydrogeno, Solution acide, Acidic solution, Solución ácida, Spectrométrie Raman, Raman spectrometry, Espectrometría Raman, Structure surface, Surface structure, Estructura superficie, Traitement surface, Surface treatment, Tratamiento superficie, Oxidized multi-walled nanotubes, and Oxygen functional groups

The influence of chemical oxidation on the electrochemical behavior against hydrogen peroxide of long and short multi-walled carbon nanotubes (MWCNT) has been investigated. Different degrees of oxidation with a sulfo-nitric mixture and with nitric acid were used and a complete physical and oxygen functional group characterization was performed by Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), acid group titration, transmission and scanning electron microscopies (TEM/SEM), elemental analysis, thermogravimetric analysis (TGA), nitrogen adsorption isotherms and cyclic voltammetry. The results revealed that electrodes modified using pristine short CNT (s-NC) present higher amperometric response against hydrogen peroxide than that obtained using long CNT (l-NC), which correlates with the greater degree of packing observed for l-NC by SEM and the long and thin structures observed in s-NC. On the other hand, the chemical oxidation process increases slightly the sensitivity of resulting electrodes, in about 25%, for both s-NC and I-NC indicating that for hydrogen peroxide oxidation the metal catalyst impurities, that are removed in the oxidation process, are not as relevant in the electrocatalysis as the increase in the capacitance values observed in the oxidized CNTs. The presence of oxygen groups introduces (a) new sites for redox reaction (pseudocapacitance) and (b) strong polar sites that would adsorb water molecules favoring double-layer formation (double-layer capacitance).

General chemistry, physical chemistry, Chimie générale, chimie physique, Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Energie, Energy, Energie naturelle, Natural energy, Energie solaire, Solar energy, Conversion photovoltaïque, Photovoltaic conversion, Cellules solaires. Cellules photoélectrochimiques, Solar cells. Photoelectrochemical cells, Aluminium III Ion, Aluminium III Ions, Aluminio III Ión, Cadmium Sulfure, Cadmium Sulfides, Cadmio Sulfuro, Cellule solaire à colorant, Dye-sensitized solar cell, Célula solar sensibilizada tinte, Cellule solaire, Solar cell, Célula solar, Conversion photovoltaïque, Photovoltaic conversion, Conversión fotovoltaica, Efficacité, Efficiency, Eficacia, Etain Oxyde, Tin Oxides, Estaño Óxido, Point quantique, Quantum dot, Punto cuántico, Rayon X, X ray, Rayos X, Spectrométrie photoélectron, Photoelectron spectrometry, Espectrometría fotoelectrón, Traitement surface, Surface treatment, Tratamiento superficie, Zinc Oxyde, Zinc Oxides, Zinc Óxido, Zinc Stannate, Zinc Stannates, Zinc Estannato, CdS quantum dot, Dye-sensitized solar cells, Photovoltaic property, and Zn2SnO4

The efficiency of CdS quantum dot-sensitized Zn2SnO4 solar cells (QDSSCs) was improved by a novel surface treatment with Al3+ ions. The driving force for electron injection was strengthened for QDSSCs owing to the reduced conduction band edge of Zn2SnO4. The efficiency of Al3+ ions-treated solar cells were improved by 44% compared with the untreated ones. Polarization measurements proved the positive movement of the Zn2SnO4 conduction band edge. Although the deposited amounts of CdS QDs decreased after the surface treatment, the electron lifetimes were prolonged and the interfacial charge recombination was inhibited, giving rise to a greatly improved short-circuit current and efficiency. By optimizing the number of cycles of chemical bath deposition, a maximum efficiency of 0.263% was achieved under the illumination of one sun (AM1.5, 100 mW cm-2).

General chemistry, physical chemistry, Chimie générale, chimie physique, Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Energie, Energy, Energie naturelle, Natural energy, Energie solaire, Solar energy, Conversion photovoltaïque, Photovoltaic conversion, Cellules solaires. Cellules photoélectrochimiques, Solar cells. Photoelectrochemical cells, Cadmium Séléniure, Cadmium Selenides, Cadmio Seleniuro, Cellule solaire, Solar cell, Célula solar, Conversion photovoltaïque, Photovoltaic conversion, Conversión fotovoltaica, Couche mince, Thin film, Capa fina, Diffraction RX, X ray diffraction, Difracción RX, Electrode, Electrodes, Electrodo, Etat amorphe, Amorphous state, Estado amorfo, Microscopie électronique balayage, Scanning electron microscopy, Microscopía electrónica barrido, Microscopie électronique transmission, Transmission electron microscopy, Microscopía electrónica transmisión, Morphologie, Morphology, Morfología, Nanocristal, Nanocrystal, Point quantique, Quantum dot, Punto cuántico, Semiconducteur II-VI, II-VI semiconductors, Structure surface, Surface structure, Estructura superficie, Titane IV Chlorure, Titanium IV Chlorides, Titanio IV Cloruro, Titane IV Oxyde, Titanium IV Oxides, Titanio IV Óxido, Traitement surface, Surface treatment, Tratamiento superficie, Spectrométrie IMVS, Intensity modulated photovoltage spectroscopy, Amorphous TiO2, CdSe quantum dot, Quantum dot-sensitized solar cells, and TiCl4 surface treatment

A TiO2 nanocrystalline thin film, sensitized by CdSe quantum dots, was further modified by a TiCl4 treatment strategy. The CdSe quantum dots with a cubic zinc blende structure were synthesized in situ on the TiO2 nanocrystalline thin films by chemical bath deposition, after which the sensitized TiO2 film was further modified by a TiCl4 treatment strategy. The modification of the amorphous TiO2 thin layer enhanced the photovoltaic performance of the quantum dot-sensitized thin film. This enhancement was detected by fabricating a solar cell based on the sensitized thin film electrode, a polysulfide electrolyte and a platinized electrode. The modified amorphous TiO2 was partly crystallized by heating the film at 200 C to analyze the effect of crystallization on interfacial recombination and the photovoltaic performance. The enhancement due to the TiCl4 treatment was attributed to the formation of an amorphous TiO2 thin layer, which separated the uncovered surface of TiO2 nanoparticles from the electrolyte, and reduced the surface states of the TiO2 nanocrystals and the quantum dots. The highest conversion efficiency was 2.13%, and it was obtained for the quantum dot-sensitized solar cell after optimizing the CdSe quantum dot deposition and amorphous TiO2 thin layer modification processes.