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Lead Acid Batteries (LABs) in the Micro Hybrid vehicle have to work in Partial State of Charge (PSoC) conditions, where the negative plates may develop high sulfation leading to the battery death. In order to reduce this sulfation, Graphitized Carbon Nanofibers (GANFg) at 0.10% and two types of Organic Expanders (OEs) were used as additives for the negative plates. These fibers were previously dispersed with a certain amount of OEs. Five mixtures were selected, and the corresponding negative plates were prepared. 2 V / 1 Ah cells were assembled and tested, together with the physicochemical properties of the plates. During the formation of the cells, GANFg are thought to be integrated into the NAM skeleton where would improve the NAM energetic structure. As a result, the use of GANFg slightly enhanced the capacity and the cold cranking ability, although this last one was essentially dominated by the OEs concentration. A lower OEs concentration led to higher charge acceptance, and the use of GANFg involved a higher water loss. However, the water loss rate was considered low in comparison with other carbon materials. GANFg addition increased the cycle life of the cells during the 17.5% DoD cycling test (at PSoC).

Graphitized Carbon Nanofibers (GANFg) were dispersed with a certain amount of organic expander and used as additive for the negative plates of the Lead Acid Batteries (LABs). Due to the high aspect ratio of these fibers, they are thought to reach the percolation threshold inside the Negative Active Material (NAM) and create a conductive network which would improve the cycle life of the LABs working in Partial State of Charge (PSoC) conditions. These fibers were added at three concentrations (0.50, 0.20 and 0.10 wt. %) and dispersed in a sodium lignosulfonate aqueous solution. Unformed negative plates of three mixtures were prepared, together with a NAM Control sample, and 2 V/1 Ah small lead acid cells were assembled for testing the electrical performance of the different mixtures (capacity, cold cranking ability, charge acceptance, negative polarization study, PSoC cycles and Cyclic Voltammetry (CV)). Continuous physicochemical analysis was carried out for the negative plates. As a result, Carbon Nanofibers were able to increase cell cycle life working in PSoC conditions and slightly improve the charge acceptance, but also raised the water loss. However, this gassing increase was lower for Carbon Nanofibers in comparison with other carbon materials used in flooded LABs.

Lead-Acid batteries have been in continuous upgrade as they are required for new applications, such as stop-start function and regenerative braking for Micro-Hybrid vehicles. These issues are closely linked to cyclability and charge acceptance whose failure is directly related to a high sulfation of the negative plates. Carbon materials can be added to the negative active material to delay this sulfation, and other organic compounds, such as lignosulfonates, take part also in the improvement of these features. In this study, different types of carbon materials and lignosulfonates were used as additives for the negative active material, and negative plates have been prepared to assembly 2 V/1 Ah small lead acid cells. The cells performed several electrical tests: capacity, cold cranking, initial charge acceptance test, negative polarization study and cycling life in Partial State of Charge. At the same time, continuous physicochemical analyses of negative plates were carried out in order to evaluate their structure and composition. As a conclusion, those carbon materials that were are able to be introduced into the lead skeleton showed performance on charge acceptance by acting as super-capacitors, and on cycle life by reducing negative plate sulfation. The carbon material that was able to remain on the lead surface was able to increase charge acceptance, but failed to complete the cycle life test due to a high sulfation on its negative plates. The type of lignosulfonate and the electrochemical surface area supplied with the carbon materials had a strong influence on hydrogen evolution.

An easy treatment based in carbon layer deposition into aluminium alloys is presented to enhance the performance of Al-air primary batteries with neutral pH electrolyte. The jellification of aluminate in the anode surface is described and avoided by the carbon covering. Treated commercial Al alloys namely Al1085 and Al7475 are tested as anodes achieving specific capacities above 1.2 Ah g−1 vs 0.5 Ah g−1 without carbon covering. The influence of the binder proportion in the treatment as well as different carbonaceous materials, Carbon Black, Graphene and Pyrolytic Graphite are evaluated as candidates for the covering. Current densities of 1–10 mA cm−2 are measured and the influence of the alloy explored. A final battery design of 4 cells in series is presented for discharges with a voltage plateau of 2 V and 1 Wh g−1 energy density.

The activity of carbon supported palladium-based catalysts towards ethanol oxidation reaction in alkaline medium is investigated. To this end, Pd and Pd x Ru (x = 1, 6, 12) materials are synthesized supported on Vulcan XC72R by a modified impregnation method. These materials are characterized physicochemically and their composition varies between 40 and 50 wt. % of metal content. The mean size of nanoparticles is below 4 nm, and the size of the majority of particles ranges from 2 to 6 nm. The catalytic activity of these samples is also tested in half-cell and alkaline membrane direct ethanol fuel cell (AMDEFC). Lower onset potential and higher oxidation current densities is observed in palladium-rich bimetallic catalysts. By using the prepared samples as anode of AMDEFC and a commercial membrane of polybenzimidazole as solid electrolyte, the maximum power density is observed for Pd 12 Ru/C, 97 mW cm −2 , almost doubling the value achieved by the catalyst Pd/C (50 mW cm −2 ), and above the obtained by commercial PtRu/C catalyst (89 mW cm −2 ).

The evaluation of commercial aluminium alloys, namely, Al2024, Al7475 and Al1085, for Al-air batteries is performed. Pure Al cladded Al2024 and Al7475 are also evaluated. Current rates from 0.8 mA cm−2 to 8.6 mA cm−2 are measured in a gel Al-air cell composed of the commercial alloy sample, a commercial air-cathode and an easily synthesizable gelled alkaline electrolyte. The influence of the alloying elements and the addition to the electrolyte of ZnO and ZnCl2, as corrosion inhibitors is studied and analysed via EDX/SEM. Specific capacities of up to 426 mAh/g are obtained with notably flat potential discharges of 1.3–1.4 V. The competition between self-corrosion and oxidation reactions is also discussed, as well as the influence of the current applied on that process. Al7475 is determined to have the best behaviour as anode in Al-air primary batteries, and cladding process is found to be an extra protection against corrosion at low current discharges. Conversely, Al1085 provided worse results because of an unfavourable metallic composition.

A Nafion ® membrane has been both electrochemically and chemically modified in-situ to incorporate polyaniline (PANi) into its structure. The proposed objective was to decrease the methanol (MeOH) permeability and thus improve the durability of a direct methanol fuel cell device. Permeability and conductivity of the modified membranes were measured using the unmodified Nafion ® 117 as a reference. The permeability was determined from the electrochemical oxidation of permeated methanol, and the conductivity was determined via electrochemical impedance spectroscopy. To evaluate the effect of these modifications, the performance of a MeOH/O 2 single-cell was measured using different MeOH flows and concentrations. The device durability was evaluated under a constant potential and at different operating times. The power density, p , at high MeOH flows and concentrations was 7 times higher for the PANi-modified membrane than the unmodified Nafion ® 117. The durability of the modified membranes containing small amounts of PANi was 2 times higher using low MeOH flows and concentrations, while the power densities were similar. Impedance measurements were performed before and after the long-term durability tests in order to identify the improvements at the different parts of the fuel cell.

A series of poly(vinyl alcohol)-blend-poly(benzimidazole) (PVA:PBI) membranes are synthesized with different ratios of PVA and PBI (2:1, 4:1, 6:1 and 8:1) using the casting method. These materials are doped in KOH 6 M solution in order to study their suitability for fuel cell applications. The Infra-red (IR) and Raman spectra confirm the successful doping of the membranes and the dimensional changes due to water and KOH uptakes during the doping are similar to other PBI-based membranes. XPS measurements are performed to evaluate the characteristics of these materials after the doping process. The thermal stability of the membranes is excellent in the range of desired temperatures (below 100 °C) and the conductivity values found are between 10−2and 10−1S cm−1. These results are optimal to consider these membranes as candidates for anion exchange membranes (AEMs) and they are tested in a single cell with ethanol as fuel. The PVA:PBI 4:1 membrane have the best behaviour in fuel cell, reaching a power density of 76 mW cm−2, approximately 50% better than the doped PBI in the same conditions. These important results can be considered highly promising for the future application of these membranes in alkaline polymer electrolyte membrane fuel cells (APEMFC)., This work has been partially supported by the Spanish Ministry of Economy, Industry and Competitiveness (MINECO) under projects ENE2016-77055-C3-1-R and CTQ2015-68844-REDT, and by the Madrid Regional Research Council (CAM) under project S2013/MAE-2882 727 (RESTOENE-2).

The understanding of the degradation mechanisms involved in the performance of direct methanol fuel cells (DMFCs), constitute important matter for the future implementation of this technology. In this context, it is necessary to develop new and reliable analysis tools to simulate realistic operating conditions. To reflect these, the present study used a “start-run-stop-run’” (SRSR’) test in three different characteristic voltages (at open-circuit potential (OCP), 0.3, and 0.1 V). The electrical loss performance at different operating times (0, 22, 40, and 60 h) working under SRSR’ test was followed by analysis of polarization curves and electrochemical impedance spectroscopy (EIS). The results reveal a decrease of 65% in the maximum density power, 30 mW/cm2, with a degradation rate of 1.2 mV/h at 50 mA/cm2. In addition, the contribution to the overall loss of fuel-cell performance was observed to follow the order: anode reaction > cathode reaction > IR resistance. Ex situ characterizations confirm this re...

The electrochemical C-H functionalization of carbamates via N-acyliminium ion is a very useful way for synthesizing biologically active and pharmaceutical products but its mechanism is not fully understood yet, specially referring to the anomalous regioselectivity that leads to the functionalization in the less substituted site which would allow to modulate the regioselectivity of the process in the asymmetric carbamates. Cyclic voltammetry experiments (with both static and rotating disk electrode) of the α-alkoxylation of carbamates prove that the mechanism for this reaction is of the type ECEC with the first two steps occurring in a concerted manner, a conclusion that is also corroborated by theoretical (DFT) values of absolute redox potentials. Further theoretical calculations show that the cause of the anomalous regioselectivity lies in the combination of the dipole moment vector of the asymmetric carbamates with the concerted ECEC mechanism.

To develop new materials for Al/air batteries, the evaluation and characterisation of commercial aluminium alloys, namely, Al2000, Al2000Clad and Al7000, as anodes in alkaline electrolyte batteries has been performed. Their self-corrosion rate, hydrogen evolution rate and electrochemical properties, including open circuit potentials, polarisation characteristics and potentiodynamic measurements, were examined in a 4 M KOH solution. Among the tested alloys, Al2000 was found to be the most promising because it exhibits a high open circuit potential, a good anode efficiency and a minimum corrosion rate. Al2000/NiOOH and Al2000/air batteries were tested. Electrolyte concentrations between 0.01 and 4 M KOH were studied, and discharge currents between 0.8 and 20 mA cm−2 were imposed to analyse the evolution of the Ecell. Conversely, the Al7000 alloy exhibited the highest corrosion rate and H2 evolution compared to the other alloys.

The present article investigates the tolerant effect exerted by a functionalised multi-walled carbon nanotube (MWCNT) support compared with the Vulcan XC-72 support for a nanoparticulate Pt catalyst. The negative effect produced in the hydrogen oxidation reaction (HOR) by the presence of a Pt contaminated with high CO coverage was analysed. This investigation was conducted using a rotating disk electrode (RDE) and a single cell with membrane electrode assemblies (MEAs) with loads of 0.3 mg Pt/cm 2 for the anode and 0.6 mg Pt/cm 2 for the cathode at various poisoning times. To this end, polarisation curves were performed, and electrochemical impedance spectroscopy (EIS) measurements were analysed. In addition, the recovery of the poisoning/de-poisoning process was studied. The –OH groups anchored to the MWCNT support exert a protective effect on the Pt nanoparticles, making the catalyst more efficient in a PEMFC fed with H 2 + CO.

Nanocrystalline nickel films have been prepared via pulse electrodeposition on steel substrates from an additive-free sulfamate-type bath. The mechanical properties of the films have been analyzed with respect to the parameters of various current programs. The mechanical properties of these films were determined using dynamic microindentation measurements known as the universal microhardness test. The hardness, plastic component, Young's modulus and percent of elastic recovery have been measured. Increasing the peak current density was more effective at improving the mechanical response of the films than varying the pulse-on time. In addition, X-ray diffraction studies have been performed to obtain the preferential orientation and grain size of the electrodeposits and scanning electron microscopy used to evaluate their morphology. All deposits exhibited a preferential orientation, and the highest performing films have been analyzed with respect to their mechanical properties. The effect of grain size, in the nanometer range, has been determined for variations in the microhardness with current density confirming the Hall–Petch relationship. These studies allow films to be tailored with good mechanical performance for various technological applications by simply selecting the appropriate electrodeposition conditions.

The long-term stability of PtCoRu/C to methanol crossover has been evaluated in a direct methanol fuel cell (DMFC) configuration. The DMFC has been subjected to continuous operation under potential step cycles. The degradation of the DMFC with PtCoRu/C has been followed by comparison of the power density curves recorded after 0, 60 and 312 h of continuous operation, and compared to that recorded for a DMFC with Pt/C. Electrochemical Impedance Spectra (EIS) were recorded directly from the DMFCs and used to identify the main degradation phenomena responsible for the loss of performance of the used fuel cell. AC impedance spectra show that the resistance of the anode reaction increases while resistance associated to the cathode reaction decreases after the long-term stability tests; however, the analysis of the power density curves unequivocally show that the performance of the DMFCs goes down during the stability tests. This apparent contradiction can be explained by taking into account the changes between the fresh and used PtCoRu/C observed by X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses. During the potential step cycles Ru dissolves form PtCoRu/C leading to Pt-enriched catalysts which are more active for the oxygen reduction reaction (lower resistance) but less tolerant to methanol (lower power density).

Functionalized carbonaceous materials have been investigated as supports of PtRu nanoparticles for the electrooxidation of methanol, using such conventional electrochemical methods as cyclic voltammetry and chronoamperommetry and by measurements in a CH3OH/O2-fed single cell. Further, to understand the effect of oxygen-containing groups on the supports in the methanol oxidation reaction (MOR), a kinetic study of the catalyst that has the best behavior in this process has been performed. The study at different temperatures of PtRu nanoparticles supported in multiwall carbon nanotubes (MWCNTs) with a high amounts of functional groups—PtRuCNT-ST—show that there was low CO poisoning during the MOR on this catalyst. The low apparent energy on PtRuCNT-ST in the MOR was attributed to CO diffusion or to the dissociative adsorption of methanol. Both factors had a beneficial effect on the oxygen-containing groups on MWCNTs, facilitating oxidation of the carbonaceous intermediates to CO2 or HCOOH. These findings have been confirmed by studies in a single cell feeding with CH3OH/O2, demonstrating that PtRuCNT-ST is the best-performing anodic electrode.

Platinum-tungsten oxides supported on Vulcan carbon were incorporated by means of an impregnation method. XRD and TEM-EDX results indicated that the material is formed by a mixture of tungsten trioxide and platinum particles supported on carbon. XPS analysis showed the presence of tungsten trioxide, metallic platinum and platinum oxides (PtO and PtO2) on the surface of the material. The catalytic performance of PtWOx/C and Pt/C for the oxygen reduction reaction (ORR) was analyzed in the absence and presence of methanol throughout cyclic voltammetry and rotating disk electrode. The results indicated that the addition of tungsten trioxide increases both the catalytic performance of the ORR and catalyst's methanol tolerance.

A series of Se-modified Ru/C (Se–Ru/C) samples were prepared from a carbon-supported ruthenium precursor. Selenium was incorporated by two different methods; in the first case, Se was incorporated by treating the Ru/C precursor in a selenious acid solution followed by reduction in H2 atmosphere. In the second case, Se was incorporated to Ru/C by means of thermal treatment in a selenium atmosphere. The samples thus obtained were characterized by different techniques: X-ray diffraction, energy dispersive X-ray spectroscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. A detailed study has been made of the structural properties and chemical composition of the different Se–Ru/C samples. Microscopy results reveal that Se is incorporated homogeneously, being preferentially located on the surface of the Ru atoms. These results agree well with XRD and XPS data. The incorporation of Se in the lattice results in the formation of RuSe2 only if RuO2 already exists. On the contrary, if Ru is in its metallic form, Se remains as an amorphous layer located on the surface of the Ru particles. The performance of the catalysts on the oxygen reduction reaction was evaluated either in the absence and presence of methanol. Se-containing samples develop more active and methanol tolerant catalysts, particularly when Se is located on the surface of the Ru particles.

In order to obtain single-phase thin films of the system Cu–In–Te with optoelectronic properties adequate for solar cells, electrodeposition techniques were used on substrates of molybdenum supported by glass. Different annealings in Te atmosphere have been done that affect the Te concentration and In/Cu atomic ratio. Single chalcopyrite phase appears in two ranges of composition where the In/Cu atomic ratio varies between 0.21–0.76 and 0.90–3.46, respectively. Morphology, cell lattice parameters and electrical resistance for single-phase samples depend strongly on the composition in the annealed samples. The cell parameters ranges are a =6.141–6.183 A and c =12.201–12.375 A.

The possibility of using TTF-derivatized SAMs as platforms for the construction of electrochemical biosensors is explored. The properties and characteristics of the electroactive SAMs formed with 4-mercaptotetrathiafulvalene (HSTTF) and 4-(mercapto-ethan-2-thiol)-tetrathiafulvalene (HSC2STTF), and their ability to promote the electron transfer between the active center of the immobilized enzyme, HRP, and the electrode surface is evaluated. Calculations from electrochemical impedance spectroscopy data showed a microarray behavior for HSC2STTF-SAMs. However, semi-infinite diffusion was not obtained for HSTTF-SAMs. The slope value of the H2O2 calibration plot obtained by flow-injection with amperometric detection at 0.00 V was more than one order of magnitude higher with the HSTTF design, which is attributed to the larger number of TTF moieties present at the electrode surface. The performance of the bioelectrocatalytic integrated devices is shown to be very dependent on the molecular structure of the TTF derivative. Keywords: Electroactive self-assembled monolayers, Tetrathiafulvalene, Integrated biosensors, Horseradish peroxidase

The structure and electrochemical properties of pure and mixed monolayers of 3-mercaptopropionic acid (MPA) and 11-mercaptoundecanoic acid (MUA) self-assembled on a gold disk electrode (AuE) have been investigated by electrochemical impedance spectroscopy (EIS) in electrolytes containing a one-electron redox couple. These results are compared with those obtained by cyclic voltammetry (CV). The monolayer surface coverage was determined using impedance measurements through the charge-transfer resistance, and by the pore size model. Cyclic voltammetry considering gold oxide formation/removal, as well as the oxidation/reduction process of a redox probe, was also employed to calculate the surface coverage. Taking into account the stability of the studied monolayers during the electrochemical experiment, the comparison of the barrier to charge transfer at both, the modified and the unmodified electrodes, resulted to be an appropriate method for estimating the surface coverage percentage given by each of the considered monolayers. The obtained results demonstrated that the MPA-monolayer-coated electrode behaves like a microelectrode array, with pinholes acting as the microelectrodes. The average size and the separation of the pinholes, estimated by the pore size model, are 1.9 and 21 μm, respectively. However, MUA forms a closely packed monolayer that acts as an ionic insulator and is virtually defect-free. The adsorption kinetics of MPA and MUA SAMs on the gold electrode (AuE) was evaluated. As expected, mixed monolayers of MPA and MUA show characteristics of both, long and short-chain alkanethiol monolayers.

Electrodeposition methods have been used to obtain polypyrrole and polyaniline polymer layers, bilayers and blends of these polymers on carbon steel by passivation of the steel surface in the electrodeposition solution (oxalic acid and monomer) between −0.5 and 0.3 V versus Ag/AgCl and subsequent electrodeposition using different techniques (potentiodynamic, galvanostatic and potentiostatic). The results obtained indicate that prepassivation gives rise to adherent polymer layers with excellent corrosion resistance. Of all the bilayers obtained, the best results are yielded with those in which polyaniline is deposited as the base for the deposition of polypyrrole. The electrodeposition of Zn microparticles on the previously deposited polymer layers promotes a great improvement in the corrosion current in highly aggressive solutions such as NaCl due to the effect of Zn as an anodic corrosion inhibitor. The drop in the corrosion rate depends on the amount of Zn deposited on the polymer layer, up to a certain point after which the protective effect ceases to be observed.

Conducting polypyrrole electrodes were obtained by galvanostatic electropolymerisation on mild steel electrodes from an aqueous solution. The electrochemical response of the coated electrodes in doped and in undoped state was compared with bare mild steel electrodes. The undoped polypyrrole coated electrode offered a noticeable enhancement of protection against corrosion processes.

Thin copper-electrodeposited films have been prepared on steel substrates from an additive-free copper sulfate bath by applying different current signals such as rectangular and square wave pulses, triangular waveform and also by direct current with variation of its magnitude. Mechanical properties of these films have been studied by means of dynamic microindentation measurements known as the universal microhardness test. Values of the hardness, plastic component, Young's modulus and percent of elastic recovery have been measured. In order to obtain the preferential orientation and grain size of the electrodeposits, X-ray diffraction studies have been made as well as scanning electron microscopy to evaluate their morphology. All the deposits showed a preferential orientation but without a simple correlation with the mechanical features of the films. The influence of current density on microhardness through its effect on grain size has been found to obey the Hall–Petch relationship in the nanometer range. Finally, correlations between the mechanical properties of the electrodeposits and the electrodeposition parameters have been made. These kinds of studies raise the possibility of tailoring films with good mechanical performance for different technological applications just by selecting the appropriate electrodeposition conditions.

Electroactive polymer films of polyaniline, poly-o-toluidine and a composite of both were deposited on stainless steel and their performance as protective coatings against corrosion was evaluated. Open circuit potential and potentiodynamic studies of the polymer-coated stainless steel in a corrosive medium showed a significant shift in the corrosion potential towards more positive values. Mechanical characteristics of the films were evaluated by means of microhardness measurements, revealing nonelastic films in all cases and low hardness values that increased from polyaniline to poly-o-toluidine to the composite. The best results were obtained in the case of the polyaniline-o-toluidine composite.

Cd X Hg 1− X Te graded thin films have been electrodeposited by applying variable deposition voltages. The range 0.05–0.15 in mercury atomic proportion has been considered. Photoelectrochemical standard measurements show that the quantum yield is enhanced when the mercury atomic proportion changes in specific ways. The quantum yield is enhanced when the outer layers are rich in mercury, but it is very poor, even inferior to the one presented by homogeneous samples when the composition varies in the opposite direction. These facts are interpreted in terms of the effects of the thermodynamic forces associated with band-edge gradients on the motion of photogenerated charge carriers.

Three different strategies for cucurbit[8]uril immobilization on a glassy carbon electrode have been assayed. The electrochemical properties of the resulting modified electrodes in solutions containing neutral, positively and negatively charged potential cucurbit[8]uril guests were investigated by cyclic voltammetry and electrochemical impedance spectroscopy. The comparison of the electrochemical behaviour exhibited by the unmodified electrodes against various probes, with respect to that of each modified electrode, resulted in an appropriate method to choose among different strategies for the development of electrochemical sensors. These sensors are based on the incorporation of the cucurbit[8]uril molecular selection properties that depend on the chemical characteristics of the potential analytes. Furthermore, atomic force microscopy was employed for the characterization of the different surfaces developed.

An experimental study of the influence of low frequency in demodulation voltammetry has been carried out for the reduction of Cd(II) in NaClO 4 . From the variation of both in-phase and quadrature components of the demodulation response, the more adequate frequency range where it is convenient to do the measurements is deduced. Likewise, a simple method of analysis to obtain the kinetic parameters of the system is presented. This method is based on the low frequency variation, the previous assumption of a reaction mechanism not being necessary.

The impedances of conducting polypyrrole films, which were prepared electrochemically, were measured. The measured impedance shows a strong anisotropy of the capacitance in directions parallel and perpendicular to the substrate. A similar observation was made with respect to resistivity. In order to interpret these results, a model is proposed which is in agreement with experimental data.

The hydrogen reactions on polycrystalline Pd in 0.1 M NaOH at 25°C have been studied by using transients at constant potential, and by impedance spectroscopy and X-ray diffraction techniques. At potentials, Es, more positive than the reversible potential, Er, for the H2 evolution reaction, the current-time response and the impedance data indicate H atom diffusion into the bulk Pd. The X-ray diffraction pattern of electrodes cathodized during 20 min at these potentials are similar to those obtained for Pd. At Es

Este artículo analiza el papel de de las instituciones políticas sobre la distribución de recursos en procesos de negociación política. Para ello, recurrimos a la metodología experimental y estudiamos 3 instituciones políticas diferentes en el laboratorio, con el fin de determinar los resultados (desde el punto de vista del bienestar y de la igualdad) de la democracia y la participación directa en las instituciones. En la institución no democrática (Dictadura), un dictador es elegido aleatoriamente al comienzo del experimento para elegir como distribuir una cantidad constante de recursos. Dos instituciones democráticas son comparadas a este tratamiento base: (i) Democracia Indirecta, en la cual el proponente es elegido aleatoriamente cada ronda; y (ii) Democracia Directa, en la cual todos los sujetos hacen una propuesta de reparto cada período. Nuestros resultados sugieren que las instituciones democráticas garantizan más bienestar y más igualdad, debido a que los participantes interiorizan y evitan el conflicto y rechazan menos propuestas cuando perciben el sistema como legítimo. Estas ganancias no están necesariamente asociadas al nivel de participación en las instituciones democráticas. Enrique.Fatas@uv.es; Sara.Godoy@uv.es

A secondary battery of the type , carbon is described. The polymer was electrodeposited on porous carbon rods, in the form of consistent, rather thick, highly porous, and low‐resistance layers. The battery was assembled in a configuration similar to that of the classical R‐6 dry cell. The performance of the battery has been studied, and it shows characteristics comparable to those of conventional systems: moderate specific energy (50–100 Wh kg−1), very good coulombic efficiency (70–100%), low self‐discharge rate (

The hydrogen reactions on polycrystalline Pd in 0.1 M NaOH at 25°C have been studied by using transients at constant potential, and by impedance spectroscopy and X-ray diffraction techniques. At potentials, Es, more positive than the reversible potential, Er, for the H2 evolution reaction, the current-time response and the impedance data indicate H atom diffusion into the bulk Pd. The X-ray diffraction pattern of electrodes cathodized during 20 min at these potentials are similar to those obtained for Pd. At Es < Er, the current transients exhibit a current maximum which increases as Es moves in the negative direction. The Nyquist plot for the rising part of the transients indicates the H atom diffusion into the bulk metal and H2 evolution on the Pd surface at high frequencies. The X-ray diffraction pattern of the electrodes cathodized at Es < Er, shows the presence of the βPdH phase and Pd. The experimental results indicate that different reactions take place simultaneously in this potential range: (i) Hs evolution, (ii) H diffusion into the bulk Pd, (iii) nucleation and diffusion-controlled growth of the βPdH phase. Taking into account the contribution of these reactions, a model, which is able to reproduce the experimental current transients, is presented., Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas

As part of the current debate on the reform of pension systems, this article examines the potential effects on consumption behaviour of implementing a lump-sum payment in a public pension system. This work explores an experimental investigation into retirement consumption behaviour with two central features: first, there exists a decreasing probability of surviving; second, there are two sequences of income, one when individual works and another when she is retired. The results show how subjects seem to plan their consumption and saving choices conditionated by both the long horizon with no incomes and the lump-sum payment. This yields, in the majority of periods, a surprising over-saving behaviour.

The electrodeposition of Mercury Cadmium Telluride (Hg1-x Cd x Te), with a variable amount of mercury, on SnO 2 substrates is studied. The effect of different postformation thermal treatments under several atmospheres, on the crystalline structure, optical and electrical properties of the electrodeposited films is described.

Layers of ln2S3 were prepared by a slurry painting method from powder of the respective semiconductor, followed by annealing in nitrogen and hydrogen. The layers were characterized by X-ray powder diffraction, surface analysis, optical properties and for their photoelectrochemical behaviour. Incorporation of the flux model InCl3 into the layers produces recrystallization and growth of large grains and it can also act as a dopant for the semiconductor.

Flat band potentials ( V fb ) of In 2 S 3 polycrystalline thin films obtained by chalcogenization of electroplated metallic indium films on Ti substrates with a flowing stream of H 2 S gas have been obtained. The variation of this potential with different redox couples, solution concentration and pH values has been studied. Photoelectrochemical characterization of the electrodes was accomplished in aqueous polysulphide solutions and the application of the Gartner—Butler model to the semiconductor/electrolyte interface makes it possible to obtain the semiconductor energy gap. The value obtained is 2.06 eV, corresponding to a direct allowed transition.

We use experimental data to obtain a detailed description of individuals' pro-sociality. Participants are faced with a large number of decisions involving variations in the tradeoffs between own and others' payoffs, as well as in other potentially important factors like individuals' positions vis-à-vis others. We find that decisions are affected by payoff trade-offs in an intuitive way but also by whether individuals obtain more or less than others. We find little reciprocity of the type linked to menu-dependence. The influence of social welfare preferences is stronger than that of difference aversion; however, Leontieff preferences are not more important than difference aversion in our data.

In a symmetric differentiated experimental duopoly we test the ability of Price Matching Guarantees (PMG) to rise prices above the competitive levels. PMG is introduced both as a market institution (the effective selling price is always the lowest posted price) and as a strategic choice so subjects have to decide whether or not to offer it. Our results show that PMG leads to a clear collusive outcome as markets quickly and fully converge to the collusive prediction if PM is imposed as a market institution. If subjects are allowed to decide whether to adopt PMG or not we observe that almost all subjects decide to adopt PMG and prices get very close to the collusive ones.

We report on an experimental study with real-world politicians. These political experts face political choice problems under risk and probability. Thus, we test the frequently observed violations of rational choice theory -the reference point effect, loss aversion, framing effects, and the common ratio effect- with experts from the field. Their choices violate expected utility theory. Nevertheless, they appear to be more rational and less risk averse (loving) in the domain of gains (losses) than student subjects.

We study whether people's behavior in a one-shot sequential public goods type situation is affected by social information about average behavior by others in the same situation. The kind of social information we consider does not directly affect subjects' payoffs and we are, therefore, able to separate pure social influence from more conventional distributional effects. We find clear evidence for other-regarding preferences; a specific patterns that we identify is that the more generous a subject, the more reciprocal his responses to others' actions. However, there is very little indication of social influence in our data. The results suggest that current static models of social preferences need not take into account the effect of social influence.

From impedance measurements of conducting polypyrrole (Ppy) films prepared electrochemically, it is shown that there is a high anisotropy of the capacitive behavior of these films parallel and perpendicular to the substrate directions, making this behavior dependent on the rate of electropolymerization. A simple morphological model based on the arrangement of the Ppy chains explaining this fact is proposed. This model is corroborated by scanning tunneling microscopy measurements.

The digital simulation method has been used to analyse the linearity of a simple electrode process. To accomplish this, some of the parameters which characterize these types of process were modified in different cases. The results obtained have been represented graphically and show clearly the perturbations which the introduced in the linearity of the system.

The reduction of In(III) in solutions containing 0.5, 0.75 and 1 M of NaI and with an ionic strength of 1.00 maintained with sodium perchlorate, has been studied by measuring the interfacial admittance spectra at different dc potentials of the dropping mercury electrode ( dme ). The frequency dependence of the admittance corresponds to that of a reversible electrode reaction with reactant adsorption. The adsorption parameters have been determined and the strange behaviour of u′ , which increases with cathodic potential must be pointed out. This seems to indicate that the adsorption occurs beyond the potential at which begin the reduction of indium. It is shown that the potential dependence of the adsorption parameters can be mathematically described by a Langmuir isotherm with the adsorption free energy being at least a quadratic function of potential. Strong adsorption effects have not been found.

The effect on the stoichiometry of a copper sulphide electrode of short-circuiting the Cu/Cuaq2+/Cu2-δS/In galvanic cell for different times has been studied. This treatment has been carried out on the copper sulphide layer of CdS/Cu2S solar cells prepared by different methods. The resulting changes of the spectral short circuit current and the I–V characteristics of the cells have been recorded. Remarkable increases in open circuit voltage, short circuit current, and fill factor have been observed as a consequence of any transformation that increases the proportion of copper in the copper sulphide films. Thus, this treatment could be a suitable method of improving the efficiency of CdS/Cu2S solar cells.

The influence of specific adsorption of electroactive species on the polarographic determination of stability constants is studied quantitatively. An expression for the term that permits correction of the effect of the adsorption and the “true” value of the constants to be obtained from the “apparent” value is deduced. The sense of the correction shows that the “apparent” constants are always higher than the “true” ones, which is in agreement with some experimental observations. Analysis of the dependence of the correction term on the adsorption parameters shows that even moderate adsorption exerts a significant influence on the values of the stability constants.

The reduction of In(III) in solutions containing 0.05, 0.1 and 0.25 M of NaI and with an ionic strength of 1.00 maintained with sodium perchlorate, has been studied by means of interfacial admittance measurements at different frequencies and dc potentials of the dropping mercury electrode. Our results demonstrate that the process takes place with specific adsorption of electroactive species. The adsorption parameters and their dependence with potential have been determined. From the analysis of our results, together with those obtained in a previous study at higher concentrations of I − , it can be deduced than InI + 2 is the species preferentially adsorbed, this adsorption taking place via a bridge-like mechanism, through I − ions previously adsorbed.

Cadmium sulphide films are electrodeposited from dimethylsulphoxide (DMSO) and propylene carbonate (PC) on stainless steel and tin oxide substrates. The physical properties of the films grown in both solvents have been studied. The thickness, grain size and morphology of the CdS films have been examined using X-ray diffractometer patterns and scanning electron microscopy. Heat treatment in argon atmosphere improves the electrical conductivity of the samples.