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Lead-acid batteries are widely used for energy storage, due to a well-established and reliable technology. Over the years, various studies for improving the performance of this battery have been performed. The main goal is to replace conventional plates with innovative electrodes having good stability, high capacity and high surface area. In particular, it is necessary to improve the kinetics of electrochemical conversion reactions at the electrode-solution interface, and to guarantee good electrical continuity during repeated charge/discharge cycles. To achieve these goals, the attention was focused on nanostructured electrodes. Up-to-date, two principal approaches have been followed. In the first approach, 3D nanostructured current collector, such as carbon foam or 3D porous titanium, was used in place of conventional lead grid. The second method is based on the fabrication of nanostructured active material, such as nanoparticles. Our idea follows the last approach, making nanostructured active material through the synthesis of nanowires. In particular, we have obtained Pb nanostructured electrodes by template electrosynthesis in nanoporous polycarbonate membrane. These electrodes have high surface area, and allow high utilization of the active material leading to high specific energy. Here, we show that battery with nanostructured Pb electrode works at 1C charge and discharge with very good stability for over 1200 cycles, and discharge efficiency around 90%. It is important to highlight that the C- rate here tested is far higher than that of commercial batteries, whose highest operative rate is C/5 while at 1C typically provide a capacity of 30 mAh g-1 for only 20-30 cycles.

NiO thin film thermally grown on Ni was investigated for the first time as an electrochemical sensor of mercury ions in water. The film was obtained by thermal oxidation in air of a commercial Ni foil. The influence of oxidation temperature, and time have been investigated by XRD, SEM, and EDS analysis. Square wave anodic stripping voltammetry was used for detecting Hg2+ ions in aqueous solution with different ion concentrations. In order to improve the response signal, all the operational parameters related to the sensing process such as pH, deposition time, potential, and square wave frequency, have been optimized. We obtained a detection limit of 4.4 ppb with a sensitivity of 1.1 µA ppb-1 cm-2.

This study was carried out to recover copper from printed circuit boards of waste computers through an electrochemical process. To simplify the overall recovery process, large pieces of printed circuit boards were used instead of pulverized samples. In particular, these large pieces were directly used as an anode for copper electrorefining. For this purpose, electronic components and solder mask were initially removed from the boards. The electronic components can be treated separately to recover precious metals using various methods. The removal of solder mask was necessary to expose copper layers to the electrolytic solution and it was removed by a chemical treatment with sodium hydroxide. Electrolytic solution was a mixture of copper sulphate and sulphuric acid, and was maintained at 60°C during the process. The recovery of copper was conducted in an electrochemical cell where the anode was supplied by a constant current of 900 mA. The deposited copper was characterized by X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. Results show a uniform cathodic deposit of pure copper having a thickness of about 32.35 µm. The copper current efficiency was of 84% with a removal degree of copper from printed circuit board of about 46%.

In the field of water-alkaline electrolyzer, the development of nanoporous low cost nickel electrodes is one of the potential approaches to increase electrocatalytic activity. Template electrodeposition is a facile and cheap technique for obtaining Ni nanowires (NWs) with high surface area. These nanostructures were fabricated by a two-step procedure. In the first step, a Ni compact layer was deposited on one side of the template where a gold film was previously sputtered, while, in the second-step, an ordered array of Ni-NWs was obtained by electrodeposition inside the template channels. The NWs were firmly connected to the underlying Ni layer, acting as a current collector. In order to enhance the catalytic activity, Pd nanoparticles were deposited onto the NW surface by metal displacement. All electrodes were characterized by Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). The comparison between the two types of electrodes revealed that the composite electrode (Ni+Pd) shows better electro-catalytic features, which quickly decay under operation, so that after 5 min. of polarization at a constant current in 30% w/w aqueous solution of potassium hydroxide, the other electrode performs better.

This work focused on the synthesis and characterization of nanostructured lead hydroxide chloride (PbOHCl) that is an innovative anode material for lithium-ion batteries (LIBs). In particular, we have obtained nanostructures of mixed PbOHCl and lead metal, directly into the pores of a commercially available alumina membrane, acting as template. The process was based on galvanic displacement reaction that was carried out in a two-compartment electrochemical cell without the use of an external power supply. This simple and cheap procedure gives regular array of Pb/PbOHCl composite nanowires. To obtain nanostructured electrodes is a significant result because, it’s well known that nanostructures have a variety of exceptional properties for Li-ion batteries applications such as high surface area, low diffusion path and good dimensional stability. This last property is fundamental because the active material of Li-ion battery are subject to very high strains due to volume change that occurs during charge/discharge cycles. In addition, the presence of lead creates a conductive network that reduces the resistivity of PbOHCl electrode.

Nanostructured materials are attracting growing interest for improving performance of devices and systems of large technological interest. In this work, the principal results about the use of nanostructured materials in the field of electrochemical energy storage, electrochemical water splitting, and electrochemical sensing are presented. Nanostructures were fabricated with two different techniques. One of these was the electrodeposition of the desired material inside the channels of a porous support acting as template. The other one was based on displacement reaction induced by galvanic contact between metals with different electrochemical nobility. In the present work, a commercial polycarbonate membrane was used as template. In the field of the electrochemical energy storage, the attention was focused on lead-acid battery, and it has been found that nanostructured morphology enhances the active mass utilization up to about 80%, with consequent increase of specific energy and cycling rates to unattainable values for the commercial battery. Nanostructured Ni-IrO2 composite electrodes showed valuable catalytic activity for water oxidation. By comparison with other Ni-based electrocatalyst, this electrode appears as the most promising anode for electrochemical water splitting in alkaline cells. Also in the field of sensing, the nanostructured materials fabricated by displacement reaction showed performance of high interest. Some new results about the use of copper nanowires for H2O2 sensing will be showed, evidencing better performance in comparison with copper thin film. In this work, we will show that nanostructured electrodes are very promising candidate to form different electrochemical setups that operate more efficiently comparing to device with flat electrode materials.

In this work, we present the performance of nanostructured array of Cu for electrochemical sensors of hydrogen peroxide. Nanostructured sensors are obtained by template synthesis in commercial polycarbonate membranes. Arrays of Cu nanowires were fabricated through a displacement deposition reaction that permits to obtain nanostructures directly and without the use of an external power supply. To test the performance of nanostructured sensors, electrochemical experiments were carried out in an aqueous solution with different amounts of hydrogen peroxide. In order to obtain sensors with stable performance, we found that it is essential to increase wettability of the nanostructures through addition of pure ethanol to the test solution. The main advantages of these electrodes are related to the high specific area (about 70 times higher than the geometrical one), which allows a low detection limit (less than 20 µM).

Lead acid batteries have a large number of potential advantages, but the high weight of lead limits their use in new technologies, like hybrid or electrical cars, which require light batteries with high specific energy. We tried to overtake this limit with nanostructured electrodes of PbO2 and Pb, obtained by electrodeposition in polycarbonate template. In the case of lead, to obtain electrodes with very good mechanical stability, a systematic investigation of electrodeposition process was needed to overcome the formation of dendrites that is the principal limitation of electrochemical production of metal lead. Nanostructured electrodes were tested in a zero gap configuration, using commercial plates as counter- electrode and an AGM type separator in a 5M H2SO4 aqueous solution. Electrochemical tests were performed in very stressing conditions, cell was discharged up to 90% of the gravimetric charge of nanostructured electrode up to a cut-off voltage of 1.2 V. Charge/discharge tests were carried out at high C-rate (2C, 5C and 10C) and excellent results have been obtained. After a short stabilization period (about 100 cycles), the nanostructured electrodes are able to work for more than 1,000 cycles with high discharge capacity. These findings indicate that lead-acid batteries made with nanostructured electrodes are able to work at high C-rate, never reached with commercially available lead-acid batteries.

Template electrodeposition has been used to grow uniform arrays of molybdenum oxide nanostructures in polycarbonate membrane. Several parameters have been investigated, like electrodeposition, time and solution pH. These parameters do not influence the nature of the deposit that always consists of mixed valence molybdenum oxides, whereas the nanostructure morphology changes with pH. In particular, at low pH (2.7), nanotubes are formed, whilst arrays of nanowires are obtained above pH 5.5. This change of morphology is likely due to H2 bubbles evolution during the electrochemical deposition, particularly occurring at low pH. It was found that fast removal of H2 bubbles through vigorous stirring of the solution favors the growth of nanostructures with a uniform length. Molybdenum oxide nanostructures were characterized by XRD, EDS, Raman, XPS and photoelectrochemical measurements. Results indicate that nanostructures are amorphous and consist mainly of MoO2 underneath ??-MoO3. The presence of these two oxides was confirmed by photoelectrochemical experiments. From photocurrent spectra, two linear regions appear in the (Iph·h?)0.5 vs. hv?plot, whose extrapolation to Iph=0 gives optical gaps values of 2.5 and 3.2 eV, which are typical of MoO2 and ??-MoO3, respectively. In addition, photoelectrochemical investigation revealed n-type conductivity of this mixed oxide deposit.

Ni nanowires (NWs) of different lengths were fabricated by pulsed potentiostatic deposition within pores of polycarbonate membranes. After template dissolution, substrates underwent sequential Spray-ILGAR® depositions of thin indium sulphide films. The effect of deposition temperature was also investigated. For low number of deposition cycles, results showed complete and uniform covering of metal over the entire length of NWs, with formation of Ni - In2S3 core-shell structures. However, with increasing number of deposition cycles films became uneven and crusty, especially at higher temperatures, owing to the simultaneous formation of nickel sulfide. This drawback was almost eliminated doubling the duration of the spray step.

In this work, we present the growth and electrochemical performance of nanostructured lead and lead oxide electrodes for lead-acid batteries. The electrodes were obtained by template electrodeposition in polycarbonate membranes, acting as template. Electrochemical tests were conducted at constant current in 5M aqueous solution of sulphuric acid, after assembling nanostructured lead and lead oxide electrodes in a zero-gap configuration using a commercially available separator. The main advantages of these electrodes are the high specific energy and power density, and the wide surface area, about 70 times higher than the geometrical one. These features allowed high discharge rates, up to 20C. Moreover, in comparison with commercial lead-acid batteries that usually deliver about 30 mAh/g for only 15-20 cycles at 1C rate, our batteries are able to charge and discharge at very high rate (1C and more) without decay up to 1200 cycles.

In this work, we present some results concerning the electrochemical fabrication of CIGS thin films and nanowires, for semiconducting p-n junction fabrication. Tuned nanowire length and composition were achieved by adjusting applied potential and electrolyte composition. Also in the case of thin films, composition was controlled by varying the concentration of metal salts in the electrodeposition bath. Deposits were characterized by X-ray diffraction (XRD), Scanning Electrode Microscopy (SEM), Raman Spectroscopy, Energy Dispersion Spectroscopy (EDS) and by photo-electrochemical measurements. XRD patterns showed that as-synthesized semiconducting compounds were amorphous, independent of deposition conditions. EDS analysis revealed the formation of CIGS compounds with different values of the Cu/(In+Ga) and Ga/(In+Ga) ratios. In order to tune the composition of CIGS, thermal treatment at ~400°C for 1h was also performed under Ar atmosphere. Photoelectrochemical measurements showed that CIGS compounds display cathodic photocurrent independent of deposition conditions, whilst different optical gap values were measured.

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A procedure based on the high-field mechanism of the growth of anodic oxides was developed in order to evaluate the morphological features of porous layers. Since the thickness of the barrier film, separating the porous layer from the metal, does not change during the steady-state growth of an anodic porous layer, the rate of displacement of the metal-oxide interface to the metal direction must be equal to the rate of displacement of the pore base to the oxide direction. As a consequence, porosity can be expressed in terms of the ratio idiss/iion, where idiss is the dissolution current density at the pore base, and iion is the ionic current density at the metal-oxide interface. Pore diameter can be determined from geometrical considerations, while average pore population can be obtained from the ratio of porosity to the average surface area of a single pore. This procedure was checked by comparison with experimental results relative to membranes prepared in various conditions. The satisfactory agreement between theoretical and experimental findings indicates that porosity can be evaluated by current density data and vice-versa. Therefore, anodic alumina membranes may be tailored for different applications by choosing operative conditions giving the desired value of idiss/iion. [ABSTRACT FROM AUTHOR]

Contamination of water with nitrate ions is a significant problem that affects many areas of the world. For this reason, European legislation has set the maximum permissible concentration of nitrates in drinking water at 44 mg/L. Thus, it is clear that a continuous monitoring of nitrate ions is of high technological interest but it must be rapid, easy to perform and directly performable in situ. In this work we have developed a nanostructured sensor based on array of copper nanowires obtained with the simple method of galvanic deposition. The nanostructured sensors have a very short response time with a detection limit less than 10 μM. Different interfering species were tested finding a negligible effect except for the chloride ions. However, this problem has been solved by removing chloride ions from the water through a simple precipitation of chloride compounds with low solubility. Nanostructured sensors were also used to analyze real water samples (rain, river and drinking water). In the case of drinking water, we have measured a concentration of nitrate ions very close to the that measured by conventional laboratory techniques., (Copyright © 2020 Elsevier B.V. All rights reserved.)

In this work, a systematic investigation of the different parameters that control the electrodeposition processes was carried out at the aim to synthetizing AgGaSe₂ nanostructures. We found that pH is a key parameter to control both the morphology and composition of the nanostructures. Low pH favours mainly the formation of Ag2Se nanotubes with a scarce mechanical stability, while multi-phase nanowires well anchored to the substrate were obtained at higher pH. We also found that it was necessary to increase dramatically the concentration of the gallium precursor into the deposition bath in order to obtain AgGaSe₂ owing to lower redox potential of the Ga 3+ /Ga couple than Ag 2+ /Ag and Se 4+ /Se. Besides, the addition of specific complexing agents to deposition bath was necessary to better control the composition of the nanostructures. By increasing gallium precursor concentration and adding complexing agents, it was possible to obtain for the first time nanostructures of amorphous AgGaSe₂ with different amount of Ga via one-step electrodeposition.

Currently, lead acid battery is extensively investigated owing to its prevalent use as a startinglighting and ignition device. An essential role for electrochemical reactions is played by the surface area available for conversion reactions and a possible approach is the use of nanostructured electrodes. In this work, lead dioxide nanostructured electrodes were tested in order to investigate the dependence of the charge and discharge behaviour on some parameters such as electrolyte concentration, and a new type of thin separator. In this last case, it is possible to reduce the size of the cell by using a very thin separator comparable to the nanostructured electrode thickness. Besides, a low concentration of electrolyte was also tested for studying its influence on the performance of a nanostructured electrode. Lead dioxide electrodes were cycled at 1C-rate and discharged to a cutoff voltage of 1.2 V up to 90% of the gravimetric capacity. Electrodes were assembled in a zero gap configuration using a commercial negative plate as counter-electrode with a large excess of active mass in comparison to the nanostructured one. Tests were conducted in very stressful conditions, in order to compare the behaviour of this new type of battery with that of the commercial one.

In this paper, we report a detailed study on the synthesis of composite nanowires of Pb-PbOHCl via galvanic deposition into the pores of a membrane acting as a template. PbOHCl deposition quantitatively occurs as the solution pH exceeds the value of about 4.12. Simultaneously, owing to the galvanic coupling, electro-deposition of lead occurs, so composite nanowires were formed. The role of different parameters controlling the kinetic evolution of the process, such as oxygen bubbling, solution pH, surface area and type of sacrificial anode were investigated one at a time. The results suggest that every modification accelerating the alkalization of the solution inside the template pores favors growth of composite nanowires richer in PbOHCl. Alumina and polycarbonate membranes were investigated as template, and the best results were obtained for polycarbonate membrane, which can be easily removed by dissolution in CHCl₃ avoiding the collapse and successive loss of the nanowires.

In this work, we present some results concerning the electrochemical behavior of nanostructured-based electrochemical sensors. In particular, the attention has been focused on Pd and Cu nanowires for detection of hydrogen peroxide and NiO thin film or Ni@NiO core-shell nanowires for detection of mercury ions. Ordered array of Pd and Cu nanowires was obtained through displacement deposition reaction in a commercial polycarbonate membrane acting as a template. The method leads to stable nanostructured electrodes of Pd and Cu with high surface area. For the detection of mercury ions, we have fabricated a Ni/NiO electrochemical sensor, obtained by mild thermal oxidation of Ni-foil. Some results on Ni@NiO core-shell nanowires were also reported. The effect of oxidation time and temperature was studied in order to compare performances of the Ni@NiO nanowire array with those of NiO thin film. All samples were characterized by XRD, SEM and EDS analysis. Electrochemical tests have been conducted in order to characterize specific electrode performance such as sensibility, selectivity, and accuracy. Highly satisfying results have been obtained.

A galvanic method to deposit chitosan coatings on stainless steel substrate is reported. Deposition of suitable coatings is desired to improve biocompatibility and corrosion resistance of metallic medical devices to be implanted in human body. In the present work, a thin hydrogel layer of chitosan was deposited on 304SS by a galvanic displacement reaction, which is advantageous first as it does not require external power supply. 304SS was immersed into an aqueous solution of chitosan/lactic acid and electrochemically coupled with magnesium acting as a sacrificial anode. SEM images showed the formation of a uniform layer of chitosan with a thickness controlled by deposition time. Corrosion tests in simulating body fluid showed that chitosan coatings shift the corrosion potential of 304 substrates toward nobler values. Finally, the cytotoxicity of the coating was investigated through cell viability assays with osteoblastic cell MC3T3-E1. The results revealed highly satisfying biocompatibility of the coating.

Psychological stressors can contribute to adverse health outcomes and lead to health disparities. To examine associations among psychological stressors, coping, blood pressure, body mass index, and body fat in ethnic minority women, we conducted a secondary analysis using data from 178 African American and Hispanic/Latina women who completed measures of perceived racial discrimination and stress, coping, blood pressure, and body composition. The mean age of participants was 45.3 (±9.3 years), and most were obese (74.2%) and had prehypertensive systolic blood pressure (125.7 ± 14.6 mmHg). Hierarchical multiple regression models indicated a significant negative relationship between racial discrimination and percent body fat, and positive associations between stress and blood pressure. Coping did not moderate the association between racial discrimination and blood pressure or body composition. Health care providers should consider psychological stressors as underlying causes for hypertension and address tailored stress-reduction coping strategies when treating African American and Hispanic/Latina women with hypertension.

In this work, brushite and brushite/hydroxyapatite (BS, CaHPO4·H2O; HA, Ca10(PO4)6(OH)2) coatings were deposited on 316L stainless steel (316LSS) from a solution containing Ca(NO3)2·4H2O and NH4H2PO4 by a displacement reaction based on a galvanic contact, where zinc acts as sacrificial anode. Driving force for the cementation reaction arises from the difference in the electrochemical standard potentials of two different metallic materials (316LSS and Zn) immersed in an electrolyte, so forming a galvanic contact leading to the deposition of BS/HA on nobler metal. We found that temperature and deposition time affect coating features (morphology, structure, and composition). Deposits were characterized by means of several techniques. The morphology was investigated by scanning electron microscopy, the elemental composition was obtained by X-ray energy dispersive spectroscopy, whilst the structure was identified by Raman spectroscopy and X-ray diffraction. BS was deposited at all investigated temperatures covering the 316LSS surface. At low and moderate temperature, BS coatings were compact, uniform and with good crystalline degree. On BS layers, HA crystals were obtained at 50°C for all deposition times, while at 25°C, its presence was revealed only after long deposition time. Electrochemical studies show remarkable improvement in corrosion resistance., (Copyright © 2016 Elsevier B.V. All rights reserved.)

A fabrication process of amorphous nanowires of Sn-Co alloys, based on electrodeposition into anodic alumina membranes, is described. It is shown that nanowires of tin-cobalt alloys with different compositions can be produced by varying electrodeposition time and concentration ratio of salts dissolved into the electrolytic bath. Importance of the chelating agent to produce amorphous Sn-Co alloys has also been addressed. Electrodepositions were carried out potentiostatically at -1 V versus Saturated Calomel Electrode and 60 degrees C for times ranging from 10 to 90 minutes; the atomic fraction of Co2+ in the aqueous electrolyte (Co2+/(Co2+ + Sn2+)) was varied from 0.33 to 0.67. Nanowires aspect ratio (height/width) was controlled by adjusting the deposition time. Alloys were characterized by scanning electron microscopy and X-ray diffraction; compositional analysis was performed by energy dispersive spectroscopy and induced coupled plasma. The highest concentration of Co in the alloy was found after 90 min of electrodeposition from a bath containing 67% of Co2+.