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A stable film of zinc hexacyanoferrate is deposited on a GC (glassy carbon) substrate following a specific electrochemical protocol. The electrode maintains its characteristic even after dry and wet processes. SEM characterization confirms the cubic morphology of the materials and the IR suggests the presence of the FeII-C-N-ZnII structural unit. The electrochemical characterization indicates a very good stability of the film, thus opening application in ion exchange system. The focus is on monovalent, divalent, and trivalent ions. These results, the zinc low toxicity, and cost make zinc hexacyanoferrate films a promising candidate for many electrochemical applications.

The paper reports a detailed study about the influence of the electrolyte composition in nickel-hexacyanoferrate (NiHCF) electrochemical behavior. Shapes and positions of the CV waves are strongly related to the cation of the supporting electrolyte, which undergoes intercalation/de-intercalation during the redox process. The electrochemical behavior of NiHCF has been characterized in different electrolyte solutions containing either pure monovalent or trivalent metal nitrates. Nickel-hexacyanoferrate permits the reversible insertion of a wide variety of monovalent, divalent and trivalent ions in aqueous solution; the characteristic potential Ep of the cathodic process depends upon the nature of the intercalated cation. Electrochemical measurements demonstrate the unprecedented fast kinetics of trivalent ion insertion associated with this material. The reported findings represent the first systematic step toward understanding the principles of multivalent charge screening and provide a novel cation intercalation mechanism in NiHCF, assisted by both water molecules and ferrocyanide vacancies. The synergistic mechanism can reduce the electrostatic repulsion and provide a preferential path for the rapid cation intercalation.

In February 2016, 47 ingots were found in the seabed of Contrada Bulala (Gela, CL, Italy) near the site where 40 ingots had previously been recovered. The ingots composition was determined to be a Cu - Zn alloy, dated by the archaeologist to the VI century B.C. This specific alloy was then known as Orichalcum. From an archaeological point of view, the first question raised about the new discovery was whether the ingots of the first and the second excavations belonged to the same shipwreck. Following the previous study, an elemental analysis was performed on the ingots from the second finding by using ICP-OS and ICP-MS techniques. The chemometric treatment of the analytical results obtained on both sets, i.e. ingots from first and second discovery, confirms their similarity. Therefore, the two findings can be considered to belong to the same naval load. The lead isotopic ratios were determined on selected/representative ingots to improve the knowledge about this treasure. Results can provide information about probable location of the lead sources, that could be very useful for the reconstruction of the ancient trade routes in the Mediterranean Sea.

The paper presents an experimental study on mortar samples taken from historic and monumental buildings damaged or collapsed following the seismic events in Central Italy (2016-2017). Sixty-one samples were analysed via a set of diagnostic investigations to characterize the mortar and correlate it with the performance of the masonry. The techniques used were: X-ray diffraction, scanning electron microscopy and microanalysis, differential scanning calorimetry, calcimetry, Fourier-transform infrared spectroscopy, soluble salt analysis by conductimetry and dosage of anionic species by ion chromatography, particle-size analysis, direct shear. Microstructural characterization of the mortars revealed differences in mortar composition depending on their provenance. In particular the samples from Norcia contained large quantities of calcite while in the mortars from Pretare, dolomite was identified. In the case of Amatrice, only a few samples showed crystalline phases and compounds ascribable to binders. These results were largely confirmed by the other chemical and physical analysis performed, and mechanical tests also demonstrated low cohesion. The tests showed that in almost all the samples, poor quality mortars were used, and, in some cases, underachieving binder mortar.

Mortar quality is a fundamental parameter to take into account when studying the structural behavior of masonry, especially under seis− mic actions. Separation between the leaves of rubble masonry can occur, inducing the partial or total collapse of the construction. A good quality mortar is essential to delay/prevent the separation of leaves, but often, especially in ancient building with a cultural value, mor− tars have low binder capabilities. The paper presents an experimental investigation on mortar specimens taken from buildings of a little municipality in Marche region, Arquata del Tronto, heavily damaged by recent earthquakes in Central Italy (2016−2017). Both diagnostic techniques as X−Ray diffrac− tion, Fourier−Transform infrared spectroscopy and calcimetry, and mechanical test as compression tests were carried out in order to cor− relate the obtained values with the performance of the original masonry.

Cobalt hexacyanoferrate (CoHCF) was electrodeposited into an organically modified silica (ormosil) film with a nanoarray of parallel, cylindrical channels, which were obtained using 20-nm poly(styrene sulfonate), PSS, beads as a templating agent. The PSS was bound to the electrode surface with 3-aminopropyltriethoxysilane, APTES. Methoxytrimethylsilane was the ormosil precursor. Electrochemically assisted processing at a positive potential where the hydrogen ion catalyst was generated was used to deposit the ormosil film. Subsequently, the PSS and APTES were removed to provide the pores. The CoHCF was deposited in the 20-nm channels by cyclic voltammetry of a freshly prepared K3Fe(CN)6, CoCl2 mixture with 1.0 mol dm−3 KCl as the supporting electrolyte. Limiting the number of electrodeposition cycles to 10–20 resulted in CoHCF nanorods in the pores, whereas with 50 cycles bulk-form CoHCF spilled over the outer ormosil surface. Electrocatalytic oxidation of cysteine was successfully performed on these nanorod arrays, which showed greater catalytic activity than bulk-form CoHCF.

The paper describes the time-dependent evolution of the electrochemical deposition of cobalt hexacyanoferrate (CoHCFe) on graphite foil electrode modified with electrochemically formed sol–gel film doped with β-cyclodextrin to impart porosity. With short-time electrodeposition, cyclic voltammetry (CV) shows a single redox couple typical of nano-sized clusters of CoHCFe, while at longer deposition times the CV’s shape evolves to the classical form of a bulk compound in which there are present two redox couples. The electrode modified with β-cyclodextrin (CD) included in the sol–gel film has an active surface that corresponds to pores created by CD stacks normal to the surface. Hence, the electrochemical formation of CoHCFe starts in these conductive pores; only at long deposition times do the clusters overlap to form moieties with the voltammetric characteristics of bulk CoHCFe.

The preparation of cobalt hexacyanoferrate nanoparticles–poly(methyl methacrylate) (CoHCF–PMMA) composites are described together with their characterization and thermochromic properties. CoHCF nanoparticles – investigated by dynamic light scattering – were prepared by optimizing solvent composition and temperature to obtain nanoparticles with a reduced degree of aggregation. The nanoparticles were embedded in a PMMA matrix to obtain a transparent coloured composite which was studied by transmission electron microscopy. The nanoparticle chromic features, enhanced by their reduced sizes, were investigated by UV–vis and FT-IR spectroscopy.

The solid-state electrochemistry and thermochromism of cobalt hexacyanoferrate (CoHCF) in a composite matrix comprising silica sol–gel and generation-4 poly(amidoamine) dendrimer was investigated and compared to analogous studies of CoHCF powders. The thermochromic behaviour over the range, 25–85 °C, of the reduced form in the sol–gel matrix differed from that of the powder. The results suggested that even in the presence of KCl in this matrix, the dominate form of the reduced CoHCF was Co 2 II Fe II (CN) 6 rather than K 2 Co II Fe II (CN) 6 . In contrast, the thermochromic behaviour of the oxidized form of CoHCF was the same as that reported for the powders. The observed cyclic voltammetric behaviour of CoHCF in the sol–gel composite matrix was the same as that of powders in terms of the electrode processes, but the influence of scan rate on the current was dependent upon the cell configuration. With the CoHCF-doped composite contacted to a solution phase, this behaviour was consistent with anion intercalation/de-intercalation control, but in a solid-state cell, a transition from a surface-controlled to a mass-transport controlled current was observed.

Biological X-ray absorption spectroscopy (BioXAS) is able to describe the metal environment in a metalloprotein and is sensitive to metal oxidation state. Coupling of BioXAS and electrochemistry permits the characterization of different oxidation states and avoids uncontrolled protein redox state changes due to X-ray beam irradiation. XAS spectroelectrochemistry requires electrochemical cells specifically designed to meet the requirements of both XAS measurements and electrochemical effectiveness in potential control. In this context, this paper describes a new cell tested with different types of working electrodes developed for BioXAS, in particular for in situ studies of redox proteins. The XAS electrochemical measurements of a relatively high-molecular-weight protein (Cu,Zn superoxide dismutase) for which it is difficult to observe direct electrochemistry have been achieved. New working electrodes, capable of fast and unmediated electron transfer, are described. The cell permits to isolate protein redox states and to measure X-ray absorption intensity during a potential scan (X-ray voltabsorptometry).

The dynamics of charge propagation in nickel hexacyanoferrate, a model metal-substituted analogue of Prussian Blue-type cyanide-bridged systems, was considered in electrolytes containing potassium and other alkali metal cations. The apparent (effective) diffusion coefficients for charge transport were determined using a large-amplitude potential-step chronocoulometry and small-amplitude potential-step chronocoulometric potentiostatic intermittent titration. The dependence of diffusion coefficient on the potential applied is consistent with the intercalation like model of the counter-cation sorption/desorption during redox processes of nickel hexacyanoferrate. Some differences in diffusion coefficients may originate from distinct charge densities (membrane properties) of the oxidized and reduced metal hexacyanoferrate structures. The existence of strong attractive interactions between an alkali metal cation and the cyanometallate matrix is also expected. The overall dynamics of charge propagation seems to be controlled by transport of electrolyte cations within the film rather than by electron self-exchange (hopping) between the mixed-valence hexacyanoferrate(III,II) ionic sites.

Electrochemical properties of thin films and microcrystalline precipitates of nickel(II) hexacyanoferrate(II, III), NiHCNFe, are strongly dependent on the method of their preparation and experimental conditions of their investigation. The films have been generated on both inert (gold) and parent metal (nickel) substrates. Interpretation of voltammetric responses of nickel hexacyanoferrate microstructures on electrodes is supported with the data of elemental analysis estimations obtained using atomic absorption and surface examination based on X-ray energy dispersive spectroscopy. Both electrodeposited films and mechanically-attached precipitates of nickel hexacyanoferrate constitute mixed structures in which the relative ratios of K and Ni to Fe reflect composition of a solution for modification, choice of the deposition potential and time, and the time and potential limits of exposure of the system to voltammetric potential cycling in potassium salt supporting electrolyte. We demonstrate here that the more positive set of peaks of nickel hexacyanoferrate is related to the electroactivity of the form containing relatively larger amount of potassium and smaller of nickel. On the other hand, the more negative set of the system’s peaks shall be attributed to the form that is largely potassium depleted and containing more nickel relative to iron. In this context, the use of the previously proposed approximate formulas, K 2 Ni[Fe II (CN) 6 ] and KNi 1.5 [Fe II (CN) 6 ], for the predominant nickel hexacyanoferrate (reduced) forms is justified.

A new aqua-soluble CuII-Na coordination polymer, {[Cu(H2O)Na(H2O)(η9-L)]·2H2O}n, was easily generated by self-assembly from copper(II) nitrate, sodium hydroxide and 2-hydroxy-5-nitro-3-(2-(2,4,6-trioxotetrahydropyrimidin-5(2H)-ylidene)hydrazinyl)benzene sulfonic acid (H3L) a new hydrosoluble arylhydrazone of barbituric acid. The complex was characterized by IR spectroscopy, elemental and single‐crystal X-ray diffraction analyses, which disclosed 1D metal-organic chains driven by the intricate nona-chelation of the fully deprotonated L3− derivative to five metal cations (three NaI and two CuII). These chains have intercalated crystallization water molecules enabling the expansion of the structure to 3D by means of extensive hydrogen bond interactions.

This paper analyses the adolescents´attitude towards the media using a sample of 423 students between 16 and 20 years old from secondary schools of Cordoba, the Argentine. The first results show that students learn and understand reality and they are able El trabajo presenta sobre una muestra de 423 alumnos entre 16 y 20 años, del nivel medio de escuelas de la provincia de Córdoba (Argentina), los resultados referidos a la actitud de los adolescentes ante los medios. Los primeros datos obtenidos demuestran que el alumno que se acerca a la realidad, aprende y comprende, y en un proceso conjunto y simultáneo logra interpretar valorativamente los hechos y efectos de situaciones cotidianas que inciden en su vida actual y su futuro.

The inclusion of a generation-4 polyamidoamine (G4-PAMAM) dendrimer in a silica sol-gel yielded a solid electrolyte that was used to encapsulate Prussian Blue (PB), iron(III) hexacyanoferrate(II), and cobalt hexacyanoferrate. The PB was synthesized in the doped silica by sequential immersion of a monolith in 0.1 M K4Fe(CN)6, water, and 0.1 M FeCl3. Inclusion of G4-PAMAM resulted in a nanoporous anion-exchange material with a capacity of 10.1 mmol g–1, which is about four times greater than the capacity of silica alone. Relative to its G0 counterpart, the G4-PAMAM doped silica increased the rate of formation of PB by a factor of ca. 20. The solid state voltammetry of PB in the doped silica had the usual features for this compound. At 0.1 V vs. a Ag quasi-reference electrode, a reversible reduction was seen; the relationship between current and scan rate was that for a surface-confined redox couple. The quasi-reversible oxidation of PB was observed at 0.85 V. Inclusion of G4-PAMAM increased the lifetime of silica as a solid electrolyte from a few days to at least three months. Raman microprobe mapping analysis demonstrated that PB was homogeneously distributed across the entire width (ca. 1 mm) of the G4-doped monolith with 20-h immersions.

Electrochemical oxidation of 2-hydroxyacridinone, the reference compound of antitumor imidazoacridinone derivatives, was studied by cyclic voltammetry (CV), spectroelectrochemical methods and controlled potential electrolysis. The photochemical oxidation was also investigated. The studies aimed to elucidate the pathway of the oxidative metabolic activation of antitumor hydroxyacridinones under biological conditions. The cyclic voltammogram at a glassy-carbon electrode in water, pH 7.4 showed the electrochemical oxidation to be an irreversible process. The main peak potential (Ep) is pH-dependent in the range of 3–10 pH units. The spectroelectrochemical experiments performed at pH 7.4 revealed that four products of electrochemical and chemical reactions were formed during the forward potential scan and they were reduced during the reverse scan. One product of this reduction represents the reversible process. Two products of the oxidative transformation of 2-hydroxyacridinone were identified by means of MS and NMR spectroscopy. The first one, p1, turned out to be a dimer: 1,1-bi(2-hydroxyacridinone), whereas the second one, p2, was an extremely unstable orthoquinone derivative. Cyclic voltammograms of p1 and p2 allowed us to identify the current peaks observed in the voltammograms of the substrate. Two pathways of 2-hydroxyacridinone electrooxidation were proposed. The contribution of each pathway to the formation of products p1 and p2 depended on the electrochemical potential (Ecp) and pH conditions. The proposed pathways were discussed with respect to the metabolic activation of hydroxyacridinones in the organism. It was suggested that the electrooxidation might be a suitable method for the synthesis of adducts between antitumor hydroxyacridinones and DNA.

The reduction process of Co III ((DO)(DOH) pn )Br 2 has been studied by X-ray absorption spectroscopy. A structural rearrangement takes place during the first reduction step, from Co III to Co II . It involves the cleavage of both axial bromide ligands. However, the reduction from Co II to Co I proceeds with retaining of the coordination geometry. These findings have also been confirmed by an ‘ad hoc’ electrochemical experiment.

Mixed nickel/palladium hexacyanoferrates have been prepared both as thin films and bulk precipitates (powders) attached to electrode surfaces. The mixed material does not seem to be a simple mixture of hexacyanoferrates of nickel and palladium, and it shows unique voltammetric and electrochromic characteristics when compared with the respective single-metal hexacyanoferrates. Electrodeposition of a mixed film is achieved by potential cycling in the solution for modification containing nickel(II), palladium(II) and hexacyanoferrate(III). It comes from elemental analysis that, in general, the stoichiometric ratios of nickel to palladium in mixed metal hexacyanoferrate films reflect relative concentrations of Pd(II) and Ni(II) in the solutions for modification. In the case of the films that have been electrodeposited from the solutions containing palladium ions in amounts lower or comparable with those of nickel ions, the mechanism of film growth seems to involve formation of nickel hexacyanoferrate during negative potential scans followed by simultaneous insertion of palladium ions as countercations into the system. In such cases, palladium ions tend to substitute potassium countercations at interstitial positions in the electrodeposited nickel hexacyanoferrate microstructures. We have determined the following stoichiometric formula, K1.74−2yPdIIyNiII1.13[FeII(CN)6] (where y

An in situ X-ray absorption spectroscopy (XAS) spectroelectrochemical study of aquocobalamin (system B12a-B12r-B12s) has been carried out in aqueous solutions buffered at different pH values. To the best of our knowledge, this is the first structural study of aquocobalamin at room temperature under controlled oxidation conditions. Most of the previous work was in fact performed using frozen samples chemically treated to produce the species. The spectroelectrochemical approach offers several advantages: (1) the reduction products may be studied without poisoning the system with chemical reductive reagents and (2) any possible variation of the oxidation state owing to the electrons produced by the incident beam is avoided as the electrode, under potentiostatic control, acts as a scavenger. The spectroelectrochemical approach, together with more careful data analysis, has led to an improved interpretation of the XAS data. These conditions were not met in previous works where the oxidation state was not controlled and multiple scattering contributions were not taken into account. The general shape of the XAS spectra of the different species is not greatly affected by pH. A signature for the base-off square-planar coordination has been evidenced for the Co(II) compound at basic pH. A new signature for Co(I), indicating square-planar coordination, has been identified on the experimental spectra and simulated in theoretical X-ray absorption near-edge structure (XANES) studies. The flexibility of the electrochemical approach, that permits to unambiguously establish the formal oxidation state, has led to very reliable values for energy shift and peak intensity variations. The experimental XANES and extended X-ray absorption fine structure (EXAFS) spectra with a very good signal-to-noise ratio have been processed using the GNXAS package that takes into account multiple scattering contributions. EXAFS and XANES independent analysis result in the same structural model. The reduction from Co(III) to Co(II) produces the most significant structural changes: the cobalt coordination number decreases from six to five, and the edge position shifts by 2.4 +/- 0.3 eV. In addition, the XANES spectra are strongly modified. The reduction from Co(II) to Co(I) produces mainly electronic effects with no apparent change of the coordination number. A discussion of the limits and potentialities of EXAFS in this type of study has also been included.

Cobalt(II) hexacyanoferrate(III, II) films show reversible electrochromic behavior in potassium salt electrolyte. Gold-covered foil was used as a conductive, optically transparent substrate onto which cobalt hexacyanoferrate films were deposited by a slow coagulation method. Both voltammetric and spectroelectrochemical results are consistent with the existence of two cobalt hexacyanoferrate forms, presumably KCoII1.5[FeII(CN)6] and K2CoII[FeII(CN)6]. The separate nature of the redox reactions of these forms is clearly evident from spectroelectrochemical measurements, particularly from voltabsorptometry, which involves monitoring of the time-derivative signal of absorbance as a function of the linearly scanned potential. Combination of voltabsorptometry with voltammetry allows determinations of molar absorptivity and film loading, and it permits changes of concentration of colored redox centers vs the applied potential to be monitored.

The electrochemical oxidation of antitumor-active 5-diethylaminoethylaminoimidazoacridinone derivatives as well as the reference acridinone analogs have been studied by cyclic voltammetry, spectroelectrochemical methods and controlled potential electrolysis to investigate the ability of imidazoacridinones to undergo oxidative metabolic activation in the organism. The cyclic voltammograms at a glassy-carbon electrode in water, pH = 7.4 show two closely spaced peaks for imidazoacridinones and one main peak for acridinones. The electrochemical processes appear to be irreversible for all compounds. Derivatives with the hydroxyl group in the position corresponding to position 2 of the acridinone molecule are easier to oxidize than the corresponding derivatives without the hydroxyl group. The studies of the reference 2-hydroxyacridinone in acetonitrile show electrochemical oxidation to be a diffusion controlled, chemically irreversible process. Two products of oxidation are formed during the forward potential scan and they react giving rise to that are reduced during the reverse scan. The first product of oxidation was isolated and identified as a dimer 1,1′-bi(2-hydroxyacridinone).

The electrochemical, UV-vis spectroelectrochemical and X-ray absorption spectroscopic characterization of some polypyrazolylborato complexes of iron(II) and iron(III) are reported. The UV-vis spectroelectrochemical results have shown that changes in spin state occur during electrochemical oxidation of some iron(II) complexes. The results of the UV-vis experiments have been correlated with the features of the X-ray absorption spectra recorded on the powdered compounds in the XANES region.

A comparative cyclic voltammetric study of hydrogen and deuterium sorption into a thin layer palladium electrode from acidic and basic solution containing cesium cations has been performed. Cesium has been detected in palladium electrodes by neutron activation analysis after hydrogen electrolysis from 0.1 M CsOH and it has a marked influence on the α- to β-phase transition only in basic solution. The results obtained are compared with those of solutions containing lithium cations [A. Czerwinski, Electrochim. Acta, 39, 431 (1994)].

Silica sol-gel (SG) films with templated pores were deposited on glassy carbon (GC) electrodes by an electrochemically initiated process. Generation-4 poly(amidoamine), PAMAM, dendrimer was included in the tetraethoxysilane precursor to facilitate pore formation. The PAMAM adsorbs to the GC, which blocks SG formation at those sites on the electrode. The pore size was 10 ± 5 nm. After removal of the PAMAM, cyclic voltammetry of Fe(CN)6 3− and Ru(NH3)6 3+ at pH 6.2 showed that the residual negative charge on the silica attenuated the current for the former and increased the current for the latter, presumably by electrostatic repulsion and ion-exchange preconcentration, respectively. This premise was supported by repeating the measurements at the isoelectric point. Methylation of the silanol sites was used to eliminate the charge of the SG. At the end-capped SG, the voltammetry of Fe(CN)6 3− and Ru(NH3)6 3+ yielded currents that were independent of pH over the range 2.1 to 7.2. Circumventing the need for the silanization by using (3-glycidyloxypropyl)trimethoxysilane as the sol-gel precursor failed because the oxygen plasma treatment to remove the PAMAM attacked the organically modified sol-gel backbone. The resulting modified electrode mitigated the influence of proteins on the voltammetry of test species and stabilized functionalize nanoparticle catalysts under hydrodynamic conditions.

An electrochemical method to detect the Isopropyl-9H-thioxanthen-9-one (ITX), a sulfur-type photo-initiator widely used in UV-curing techniques to promote the polymerization of inks, in a hydro-alcoholic solution, has been developed and tested in a commercial wine sample. The experimental parameters of electroanalytical techniques, mainly differential pulse voltammetry (DPV), as well as the alcohol/water ratio have been optimized to improve the sensitivity and to lower the minimum detectable value. The proposed analytical method has been tested on real samples of commercial wine finding out a decision limit of 2.3 × 10−7 M and a minimum detectable value of 4.5 × 10−7 M.

The electrochemical behavior of NiS 2 has been studied in NaCl saturated NaAlCl 4 melts at 175 o C. Slow scan rate cyclic voltammetric results indicate that the reduction of NiS 2 to Ni proceeds through a series of reversible steps each involving formation of an intermediate solid phase with decreasing sulfur content. The different phases formed during the reduction have been characterized by x-ray diffraction analysis. The dependence of the peak parameters on the scan rate indicates that the electrochemical processes are controlled by the ohmic resistance. The formal and nucleation potentials of each redox couple have been deduced from the voltammetric data

(1) Adsorbed carbon monoxide inhibits the hydrogen absorption and desorption reactions in a thin-layer palladium electrode. A“blocking” effect of adsorbed hydrogen inside the palladium by adsorbed carbon monoxide is observed. (2) During CO adsorption at 0.00 V an anodic current appears, probably due to the oxidation of adsorbed hydrogen during the exchange with carbon monoxide molecules. (3) In addition to “bridged” and “linearly” bonded CO molecules as the predominant surface species, another adsorption product may exist on the palladium surface. (4) Electrodes constructed by depositing a thin layer of Pd on gold allow the ratio between absorbed and adsorbed hydrogen to be decreased. This creates new possibilities for electrochemical studies of this metal.

Cobalt(II) hexacyanoferrate(III,II) a system analogous to prussian blue, is a unique electrochromic material: its color is not only dependent on the oxidation potential, but also on the nature of the countercations sorbed from electrolyte during reduction. The electrodeposition of cobalt hexacyanoferrate thin films, their voltammetric behavior and spectroelectrochemical identity are reported here in potassium and sodium electrolytes. The oxidized film is purple brown in both electrolytes, but following reduction, the system turns olive-brown in 1 M KCl and becomes green in 1 M NaCl.

Vanadium pentoxide materials prepared through sol-gel processes act as excellent intercalation hosts for lithium as well as polyvalent cations. A chemometric approach has been applied to study the X-ray absorption near-edge structure (XANES) evolution during in situ scanning of the Cu(0.1)V(2)O(5) xerogel/Li ions battery. Among the more common techniques, the fixed size windows evolving factor analysis (FSWEFA) permits the number of species involved in the experiment to be determined and the range of existence of each of them. This result, combined with the constraints of the invariance of the total concentration and non-negativity of both concentrations and spectra, enabled us to obtain the spectra of the pure components using a multivariate curve resolution refined by an alternate least squares fitting procedure. This allowed the normalized concentration profile to be understood. This data treatment evidenced the occurrence, for the first time, of three species during the battery charging. This fact finds confirmation by comparison of the pure spectra with the experimental ones. Extended X-ray absorption fine structure (EXAFS) analysis confirms the occurrence of three different chemical environments of Cu during battery charging.

Cobalt hexacyanoferrate (CoHCF) nanoparticles have been synthesized by mixing aqueous solutions of K3Fe(CN)6 and CoCl2 under vigorous stirring at different temperatures and following two different procedures, drop-by-drop or immediate mixing. The resulting CoHCF nanoparticles, with dimensions of several tens of nanometers, were characterized using TEM, SEM-EDX, IR, and XRD. Their electrochemical behavior was investigated in comparison with the CoHCF powder bulk compound. The CoHCF nanoparticles exhibit an electrochemically driven conversion to the bulk one that has been investigated by a chemometric approach in order to establish the best synthetic parameters. The rate and the degree of conversion depend on the synthesis temperature.

The theory and equations of linear sweep voltammetry with a finite diffusion space have been modified for derivative linear sweep voltabsorptometry. For a simple uncomplicated electron transfer the time derivative d A /d t of the absorbance of the product of an electrode reaction is morphologically equivalent to the corresponding voltammogram. The shape and position on the potential axis depend on a single parameter, expressing the ratio of the diffusion space to the diffusion layer thickness, which determines the transition between thin-layer-type behaviour (optically transparent thin-layer electrodes) and semi-infinite linear diffusion (optically transparent electrodes). The theory has been verified using the oxidation of o -tolidine as the model system. The theory of linear sweep voltabsorptometry for reversible electrode reactions has been extended to cover all the possible experimental cases from thin-layer or surface wave at OTTLEs to semi-infinite linear diffusion in the case of OTE cells. The procedure outlined to derive the equation of d A /d t versus E from j versus E curves is completely general. The d A /d t signal is a “true” current analogue, at least in all the cases where kinetic complications involving the reduced species are absent. This means that the equations developed for linear sweep voltammetry are directly applicable, after the appropriate modifications, to voltabsorptometry. The theory has been proved to be applicable also to minigrid electrodes that behave as planar electrodes only at long times. The deviations seen at high scan rates appear to apply only to the potential parameters of the curves with special regard to the peak half-widths. The voltabsorptograms appear, as usual, “cleaner” than the corresponding current signals because the absorbance is not affected by the capacitive background or by contribution due to side reactions.

(1) Adsorbed carbon monoxide inhibits the hydrogen absorption and desorption reactions in a thin-layer palladium electrode. A“blocking” effect of adsorbed hydrogen inside the palladium by adsorbed carbon monoxide is observed. (2) During CO adsorption at 0.00 V an anodic current appears, probably due to the oxidation of adsorbed hydrogen during the exchange with carbon monoxide molecules. (3) In addition to “bridged” and “linearly” bonded CO molecules as the predominant surface species, another adsorption product may exist on the palladium surface. (4) Electrodes constructed by depositing a thin layer of Pd on gold allow the ratio between absorbed and adsorbed hydrogen to be decreased. This creates new possibilities for electrochemical studies of this metal.

The dirhodium(I) complex Rh 2 (CO) 2 (PPh 3 ) 2 (μ-3,5-Me 2 pz) 2 undergoes two consecutive oxidation processes at a platinum electrode in dichloromethane. The first oxidation gives the corresponding cationic species, [Rh 2 (CO) 2 (PPh 3 ) 2 (μ-3,5-Me 2 pz)] + , as inferred from the electrochemical (voltammetric and coulometric) and spectroelectrochemical data and from spectroscopic (IR, ESR and visible) examination of the oxidized product. The more anodic process involves poisoning adsorptions on the electrode surface, which rules out any effective study. Suggestions concerning the electronic charge distribution inside the monocationic compound are advanced on the basis of the voltammetric and ESR data.

The electrochemical behaviour of the “Costa-type” coenzyme B 12 model neopentyl- N 2 , N 2 '-propane-diylbis (2,3-butanedione-2-imine-3-oxime) Co(III) perchlorate complex has been studied using a platinum inlaid disk microelectrode techniques over a wide range of supporting electrolyte concentrations, and thin-layer absorption spectroelectrochemistry. In the former case, the separation of the two single electron transfers leading to Co(I) increased with decreasing supporting electrolyte concentration and, at the same concentration of the supporting electrolyte, with increasing radius of the cation. The likely explanation for this behaviour is the influence of ion-pair formation on the reduction potential of the redox couple involved in the second electron transfer that leads to a Co(I) complex bearing a negative charge. It has been demonstrated that the plot of the derivative of the steady-state current with respect to the electrode potential vs. E is morphologically identical to the derivative of the absorbance in thin-layer spectroelectrochemistry, and that the correlation between the results obtained using the two different techniques is useful for a better understanding of the electrochemical process.

The adsorption of 4,4′-bipyridyl on gold electrodes has been studied by electrochemical methods in both neutral and acidic solutions. The adsorption is a one-centre reaction involving displacement of water molecules from metal surface. The Langmuir-type equation for adsorption is obeyed. The results support previous findings that adsorbed molecules are perpendicularly oriented towards the electrode surface.

A composite of silica sol–gel, generation-4 poly(amidoamine) dendrimer (PAMAM) and cobalt hexacyanoferrate (CoHCF) was synthesized as a potential electrochromic material. The solid-state voltammetry of the material had suggested that the two electroactive sites were present. To elucidate the redox properties, the electronic and the structure in the local atomic environment of Fe and Co was investigated by X-ray absorption spectroscopy (XAS). Although the nominal stoichiometries of the investigated CoHCFs were Co 2 II Fe II (CN) 6 (or K 2 Co II Fe II (CN) 6 ) and KCo II Fe III (CN) 6 , the spectral data demonstrated that Co III was present in the composite. Among the supporting evidence for some metal-to-metal electronic transition of Fe III –CN–Co II to Fe II –CN–Co III was the shortening of the measured Co–N bond length in accord with the formation of Co III . Further, IR measurements confirm the occurrence of charge transfer between Fe and Co sites in the silica–PAMAM composite.

Cobalt(II) hexacyanoferrate(III,II) a system analogous to prussian blue, is a unique electrochromic material: its color is not only dependent on the oxidation potential, but also on the nature of the countercations sorbed from electrolyte during reduction. The electrodeposition of cobalt hexacyanoferrate thin films, their voltammetric behavior and spectroelectrochemical identity are reported here in potassium and sodium electrolytes. The oxidized film is purple brown in both electrolytes, but following reduction, the system turns olive-brown in 1 M KCl and becomes green in 1 M NaCl.

A deconvolution method, based on Fixed Size Window Evolving Factor Analysis (FSWEFA) has been developed to analyse the spectroelectrochemical sequence of spectra obtained in OTTLE electrodes for EE electrochemical processes. The analysis of the data permits to reconstruct the concentration profiles, the spectra of the intermediates and an optical analogue of the i vs E curve.

A new `quasi-solid state' spectroelectrochemical cell for in situ XAS measurements is described and tested using microperoxidase as reference material. The cell substantially improves conventional thin layer cells used for solution XAS spectroelectrochemistry in terms of assembling time and, more important, equilibration of the redox system under study with the applied potential. Spectra can be, in fact, recorded simultaneously during a slow scan rate cyclic voltammetric scan thus permitting correlation of the spectra and the electrochemical curve. Other advantages are the possibility to use very small quantities of material also with second-generation rings. With high intensity sources having focussed beams a further decrease of the specimen weight can be easily obtained and the acquisition time of spectra further reduced.

Hybrid organic/inorganic films, composed of polyaniline (PANI) matrix and Prussian blue-like nickel hexacyanoferrate redox centers, showed reversible electrochromic behavior in acidic potassium salt electrolytes. The system's coloration properties were assessed from various spectroelectrochemical measurements including voltabsorptometry that involved monitoring of the time-derivative signal of absorbance at 700 and 410 nm as a function of linearly scanned potential. Gold-covered foil was used as a conductive, optically transparent, substrate onto which the composite film was electrodeposited by potential cycling in the mixture for modification consisting of aniline monomer, Ni2+, Fe(CN)63− and electrolyte containing K+ and H+ ions. An important feature of hybrid (composite) material was that its electrochromic properties were dominated by color changes occurring in the PANI component. Coloration originating from nickel hexacyanoferrate barely affected the system's electrochromic characteristics. But the cyanometallate redox centers distributed in the PANI matrix behaved reversibly as expected for a system capable of fast charge transport.