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It is well known that physical and surface properties of nanomaterials are promising to enhance efficiency of nanostructured devices for sensing and for sustainable energy production, conversion, and storage. However, the practical use of nanomaterials is often complicated by the lack of scalable and cost-efficient synthesis procedures and the challenge of integrating into devices 1D nanomaterials saving their structural features. In this field, one of the most severe challenges is to find suitable methods for fabricating nanomaterials. Over the years, numerous preparation methods were proposed in the literature, but not all of them are easily scalable and economically advantageous for industrial application. In this context, electrochemical deposition in template is a facile method for fabricating either two- or one-dimensional nanostructured materials because it allows to easily adjusting the fundamental parameters controlling their final features. Electrochemical processes are, usually, cheap and environmental friendly, and they can be easily scaled-up from lab to industrial level. In this chapter, we will describe different electrochemical methods, electrodeposition, galvanic deposition electroless deposition and electrogeneration of base, that permit to obtain different type of nanomaterials such as metals, oxide, and semiconductors. In addition, also the performances of different nanostructured materials are presented.

During the last decades, biomaterials have been deeply studied to fabricate and improve coatings for biomedical devices. Metallic materials, especially in the orthopedic field, represent the most common materials used for different type of devices thanks to their good mechanical properties. Nevertheless, low/medium resistance to corrosion and low osteointegration ability characterizes these materials. To overcome these problems, the use of biocoatings on metals substrate is largely diffused. In fact, biocoatings have a key role to confer biocompatibility features, to inhibit corrosion and thus improve the lifetime of implanted devices. In this work, the attention was focused on Hydroxyapatite-Chitosan (HA/CS) and Hydroxyapatite-Polyvinylacetate (HA/PVAc) composites, that have been studied as biocoatings for 304 SS based devices. Hydroxyapatite was selected for its osteoconductivity due to its chemical structure similar to bones. Furthermore, Chitosan and Polyvinylacetate are largely used yet in medical field (e.g. antibacterial agent or drug deliver) and in this work were used to create a synergic interaction with hydroxyapatite to increase the strength and bioactivity of coating. Despite bio-coatings were obtained by different techniques, in this work, they were fabricated by galvanic deposition process that has different advantages, among which it does not require external power supply. It is a spontaneous electrochemical reaction in which materials with different standard electrochemical potential were short-circuited and immersed in an electrolytic solution. Electrons supplied by the anodic reaction at the less noble electrode flow to cathode where they oxidize the less noblest ions in solution. SEM, EDS, XRD and RAMAN were performed for chemical-physics characterization of biocoatings. Polarization and impedance measurements have been also carried out to evaluate corrosion behavior. Besides, in-vitro cytotoxicity assays have been done for the biological features.

In this work we present some results of an extensive investigation aimed to find suitable conditions to grow CuZnSnSe (CZTSe) nanostructures through single-step electrodeposition into the channels of polycarbonate membranes. After the optimization of several electrodeposition parameters, we have found that pulsed current deposition, between 0 and -1 mA cm-2, is the best way to obtain CZTSe nanostructures mechanically attached to the support. An interesting result concerns the effect of supporting electrolyte in the deposition bath. In fact, changing its concentration it is possible to vary morphology of nanostructures from nanotubes to nanowires. In both case uniform arrays of ordered nanostructures were obtained on a Ni current collector that are very stable also after thermal treatment at 550°C.

The great success of anodic alumina membranes is due to their morphological features coupled to both thermal and chemical stability. The electrochemical fabrication allows accurate control of the porous structure: in fact, the membrane morphological characteristics (pore length, pore diameter and cell density) can be controlled by adjusting the anodizing parameters (bath, temperature, voltage and time). This article deals with both the fabrication and use of anodic alumina membranes. In particular, we will show the specific role of the addition of aluminum ions to phosphoric acid-based anodizing solution in modifying the morphology of anodic alumina membranes. Anodic alumina membranes were obtained at −1 °C in aqueous solutions of 0.4 M H3PO4 added with different amounts of Al(OH)3. For sake of completeness, the formation of PAA in pure 0.4 M H3PO4 in otherwise identical conditions was also investigated. We found that the presence of Al(OH)3 in solution highly affects the morphology of the porous layer. In particular, at high Al(OH)3 concentration (close to saturation) more compact porous layers were formed with narrow pores separated by thick oxide. The increase in the electric charge from 20 to 160 C cm−2 also contributes to modifying the morphology of porous oxide. The obtained anodic alumina membranes were used as a template to fabricate a regular array of PdCo alloy nanowires that is a valid alternative to Pt for hydrogen evolution reaction. The PdCo alloy was obtained by electrodeposition and we found that the composition of the nanowires depends on the concentration of two metals in the deposition solution.

Organometallic perovskites are one of the most investigated materials for high-efficiency thin-film devices to convert solar energy and supply energy. In particular, methylammonium lead iodide has been used to realize thin-film perovskite solar cells, achieving an efficiency higher than 20%. Different fabrication procedures based on the spin-coating technique have been proposed, which do not ensure homogenous morphologies. In this work, we present a scalable process to fabricate methylammonium lead iodide thin films directly on conductive substrates, consisting of electrodeposition and two subsequent chemical conversions. A thorough investigation of the morphological, structural and compositional properties of the layer is performed after each fabrication step. It is demonstrated that this method allows fine control of the thickness of the layer by tuning the cell parameters during the electrodeposition step. X-ray diffraction patterns and energy-dispersive X-ray analysis indicate the achievement of high-purity methylammonium lead iodide layers. Micro-Raman analyses were used to demonstrate the formation of methylammonium lead iodide. Finally, ultraviolet-visible absorption spectra were acquired to determine the optical band edge of the layer ( 1.56 eV) and the absorbance of methylammonium lead iodide as a function of the film thickness. As expected, the material exploits excellent optical properties, achieving an absorption ≥ 99.9% in the entire visible range for a layer thickness of 1.3 µm. The results presented here pave the way for the application of cost-friendly solution-based processes to fabricate high-quality perovskite solar cells.

A nanostructured electrochemical sensor of hydrogen peroxide was fabricated growing self-standing Pd nanowires (Pd NWs) into polycarbonate (PC) membranes through a simple metal galvanic deposition. Conditions of deposition were adjusted in order to attain 2–5 μm long Pd wires. Characterization of Pd-NWs was performed by scanning electrode microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction. Properties of the nanostructured sensor were studied by cyclic voltammetry and chronoamperometry in phosphate buffer—ethanol solution. Addition of pure ethanol to the test solution was essential in order to increase wettability of the nanostructures. Sensing features were compared with those of both compact and nanoparticle film. Results show stable behavior and sensitive response of Pd NWs towards H 2 O 2 with a wide linear dependence over H 2 O 2 concentration for the electrodes consisting of long Pd nanowires/nanotubes, which display an increase of sensitivity and lower limit of detection (LOD) in comparison with the other sensors. Also the linear-response interval widens with electrode specific surface area. Accuracy and selectivity (towards different electroactive species) is excellent.

In this work, the galvanic deposition method is used to deposit coatings of brushite/hydroxyapatite/polyvinyl acetate on 304 stainless steel. Coatings are obtained at different temperatures and with different sacrificial anodes, consisting of a mixture of brushite and hydroxyapatite. Samples are aged in a simulated body fluid (SBF), where a complete conversion of brushite into hydroxyapatite with a simultaneous change in morphology and wettability occurred. The corrosion tests show that, compared with bare 304, the coating shifts Ecorr to anodic values and reduces icorr Ecorr, and icorr has different values at different aging times due to chemical interactions at the solid/liquid interface. The best performing deposits are those obtained by using Al as the sacrificial anode. The metal ion release, measured after 21 days of aging, is very low and is attributable to the presence of a coating that slows the steel corrosion. Coating cytotoxicity is investigated through cell viability assays with MC3T3-E1 osteoblastic cells. The results reveal a high cytocompatibility comparable to that of a pure cell culture medium.

In thiswork, the electrodeposition of Cu2ZnSnS4 thin films on molybdenum thin foilwas reported. In order to guarantee co-deposition of elements with different standard electrochemical potential, an aqueous electrolyte added with ligand agents was used. I addition, deposition parameters were carefully chosen, in order to ensure good quality and suitable composition of the films. The deposited films were sulfurized in controlled atmosphere at 580?C, scrutinizing the influence of the annealing conditions on the features of the films. Structure, morphology and composition were investigated by XRD SEM, EDS and Raman spectroscopy. Results reveal the growth of good quality films, with a uniform morphology and chemical composition suitable for solar cell application.

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%.

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 paper presents an innovative lead acid battery, based on nanostructured active materials. Both charging time and specific energy are greatly enhanced in comparison with commercial lead acid battery. Starting from the extremely valuable performances of the nanostructured battery, also a circuital model, for application in electric vehicle traction, has been specifically developed. The circuital model has demonstrated that an enhanced nanostructured battery allows an increase of traveled distance by electric vehicles.

AgSe based nanostructures (nanowires or nanotubes) were obtained by electrodeposition. A systematic investigation was carried out, varying concentration of the precursors, pH of the electrolytic solution, ligands, and deposition mode, to study the effect of all these parameters on the growth of nanostructures. Nanostructure morphology depends also on the type of metal that was used as support, due to the secondary reaction of hydrogen evolution. On Ni support, the H2 evolution reaction led to formation of only nanotubes, while on copper substrate also nanowires were obtained. Composition of nanostructures depends strongly on solution pH. X-ray diffraction and Raman spectroscopy showed that in thiocyanate-free bath nanostructures consist in orthorhombic Ag2Se and metallic Ag. At higher pH values, the metallic Ag phase increased and the co-deposition of Se also occurred. We also found that the use of a thiocyanate bath with a specific composition permits to obtain nanostructures of pure orthorhombic Ag2Se.

Nanostructured Ni–IrO2 electrodes were fabricated by electrodeposition in a two-step procedure: first arrays of nickel nanowires (NWs) were electrodeposited within pores of polycarbonate (PC) membranes, then iridium oxide nanoparticles were deposited on the Ni metal after membrane dissolution, for improving the catalytic activity. The aim was to compare performance of these electrodes with traditional ones consisting of Ni film. Different methods of deposition of the IrO2 electrocatalyst were investigated and the effect on electrodes stability and activity is discussed. Despite a low coverage of Ni NWs by the electrocatalyst, results indicate a faster kinetics of O2 evolution in 1 M KOH solution and an improvement of performances for electrolysers having a nanostructured anode.

Electrochemical deposition of SnCo alloys inside the nanometric pores of commercial membranes is described. Composition, morphology and crystallographic structure of the synthesized nanostructured alloys are reported as well as the results of electrochemical tests carried out both in half-cell and in full battery configuration to investigate the performance of these SnCo alloys as anodes for lithium-ion batteries. Optimized depositions yielded nanostructured alloys that performed 200 deep galvanostatic cycles at C/2 and 30 °C with 80 % capacity retention and coulombic efficiency higher than 97 % after 40 cycles Moreover, charge-discharge rate capability tests showed the high performance of these SnCo alloys at high C-rate such as 10C. Tests of SnCo alloys in battery configuration against LiFePO4 cathode are also reported.

Very thin and uniform layers of indium sulfide were deposited on nickel nano-rods using the sequential and cyclical Spray-ILGAR® (Ion Layer Gas Reaction) technique. Substrates were fabricated by electrodeposition of Ni within the pores of polycarbonate membranes and subsequent chemical dissolution of the template. With respect to the depositions on flat substrates, experimental conditions were modified and optimized for the present geometry. Our results show that nano-rods up to a length of 10 μm were covered uniformly along their full length and with an almost constant film growth rate, thus allowing a good control of the coating thickness; the effect of the deposition temperature was also investigated. However, for high numbers of process steps, i.e. thickness, the films became uneven and crusty, especially at higher temperature, mainly owing to the simultaneous side reaction of the metallic Ni forming nickel sulfide at the surface of the rods. However, such a problem occurs only in the case of reactive nano-rod materials, such as less noble metals. It could be strongly reduced by doubling the spray step duration and thereby sealing the metallic surface before the process step of the sulfurization. Thus, quite smooth, about 100 nm thick coatings could be obtained.

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 H2O22 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.

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.

Nanomaterials are very promising to enhance device performances for sensing, sustainable energy production, and energy conversion and storage, as extensively reported in the literature [1-3]. In this field, one of the most severe challenge is to find suitable methods for fabricating nanomaterials. Over the years, numerous preparation methods were proposed in the literature, but not all of them are easily scalable and economically advantageous for industrial application. In this context, electrochemical deposition in template is a facile method for fabricating either two- or one-dimensional nanostructured materials because it allows to easily adjust the fundamental parameters controlling their final features [4]. In addition, electrochemical processes are, usually, cheap and environmental friendly, and they can be easily scaled-up from lab to industrial level. For these reasons, the attention was focused on the synthesis of different type of nanomaterials for application in electrochemical sensing of H2O2, in lead-acid and lithium-ion batteries, in solar cells, and in electrochemical water splitting. Here, we will present an electrochemical method for obtaining dimensionally stable nanostructured electrode characterized by the presence of uniform array of nanowires and/or nanotubes with very high surface area (a typical morphology is shown in Figure 1a). The findings demonstrate that nanotechnology is beneficial for improving the resulting device performances. In this work, in addition to the fabrication method, also the performance of different nanostructured materials are presented, and discussed. In particular, the use of PbO2 nanowires (Figure 1) as positive electrode in lead acid batteries and of Ni-IrO2 nanowires in alkaline electrolyzer (Figure 2b) are presented. Besides, preliminary results (Figure 2c) on the use of Cu and Pd nanostructures as electrochemical sensors for detection of H2O2are also showed. References [1] N. A. Fromer, M. S. Diallo, J Nanopart Res 15 (2013) 2011-2015. [2] Q. Zhang, E. Uchaker, S. L. Candelaria, G. Cao, Chem. Soc. Rev.42 (2013) 3127-3171 [3] P. Si, Y. Huang, T. Wang, J. Ma, RSC Adv. 3 (2013) 3487-3502. [4] G-R. Li, H. Xu, X-F. Lu, J-X. Feng, Y-X. Tong, C-Y. Su, Nanoscale 5 (2013) 4056-4069. Acknowledgement: This work was partially funded by U.E. through PON03PE_00214_1 - Nanotecnologie e nanomateriali per i beni culturali (TECLA)

In the last years many attention has been dedicated to the increase of performance of Nichel based electrodes to use in water-alkaline electrolyzes. In our preliminary work we have shown that alkaline electrolyzer made with Ni nanowires covered with IrO2 (side oxygen evolution) nanoparticles and a Ni sheet (side hydrogen evolution) have very good and stable performance also at room temperature [1]. In this work, to obtain a complete nanostructured electrolyzer, the attention was focused on the fabrication of electrodes for hydrogen evolution. In particular, by metal displacement deposition we have grown on Ni nanowires electrodes, nanoparticles of Pd with the aim to enhance the electrocatalytic efficiency of Ni nanowires. Several parameter of galvanic process of Pd deposition were studied, such as deposition time, concentration of palladium precursor in solution and so on. The results on the growth and characterization of these nanostructured composite electrodes will be presented and discussed. Besides, the preliminary test on the electrochemical performance of nanostructured electrolyzer, carried out at constant current in 1M aqueous solution of potassium hydroxide, will be also reported. [1] M. Battaglia, R. Inguanta, S. Piazza, C. Sunseri. International Journal of Hydrogen Energy 39, 16797-16805.

Today, electrochemical sensors are considered very interesting in comparison to conventional techniques because they are very adaptable, cheap, have very low limit of detection and low detection time. The most used electrochemical technique is the amperometry . In amperometric sensors, a fixed potential is applied to the electrochemical cell, and a corresponding current, due to a reduction or oxidation reaction, is then obtained. This current it can be correlated with the bulk concentration of the detecting species (the solute) such as H2O2. Hydrogen peroxide is an essential mediator in food, pharmaceutical, clinical, industrial, and environmental analyses therefore, it is of great importance to detect H2O2. The key point in developing electrodes for detecting H2O2 is to decrease the oxidation/reduction overpotentials [1]. For this purpose it is essential to select the correct electrodic material. Among them the use of electrodes made of metals is very interesting because of their stability and durability. It is well known that platinum is the best electrodic material but, due to the very high cost of this precious metal, the attention was focused on the development of others cheaper metallic electrode. Here we have selected Pd and Cu because exhibit excellent catalytic behavior toward H2O2. To improve the electrochemical performance of these materials, we have fabricated these electrodes in nanostructured shape. In particular we have obtained regular and order array of Pd and Cu nanostructures with high structural regularity and tunability, well spatial orientation and arrangement. These morphological properties permit to take advantage of the high surface area and thus improve the performance of the sensors. Nanostructured arrays were obtained by a home-made procedure based on the displacement deposition reaction that allows to fabricate the electrodes without the use of an external power supply [2]. After synthesis, electrodes were tested for amperometric detection of hydrogen peroxide to find the sensor features. Here some preliminary results of the fabrication process and on the electrochemical tests were reported. [1] Y. Shao, J. Wang, H. Wu, J. Liu, I. A. Aksay, Y. Lina, Electroanalysis, 2010, 22, 1027-1036. [2] R. Inguanta, S. Piazza, C. Sunseri, Electrochemistry Communication, 2009,11, 1385-1388.

Hydroxyapatite (HA, Ca10(PO4)6(OH)2) is a basic calcium phosphate mineral with chemical composition similar to that of bones and teeth. Owing to this peculiarity HA is a biocompatible material of high medical interest. Unfortunately, it possesses poor mechanical properties, because is brittle, has a low fracture resistance and a poor wear resistance. For these reasons, in the last years the research was been focused on the use of HA as a coating of another biomaterial that acts as support. The best choice is that to use a substrate that must be bionert and mechanically stable, such as 316L stainless steel (316LSS). This is useful for biomedical implants, because of its excellent biocompatibility and good mechanical properties. However, since 316LSS is a bioinert material, it cannot form strong chemical bonds with bones. To improve the osteointegration, it is necessary to cover 316LSS substrates with hydroxyapatite layers. Thus, the use of bio-device based on HA coatings supported on 316LSS allows to exceed the two of principal disadvantages that these two materials present when are used individually: the brittleness of HA and the poor osteointegration of 316LSS. Many methods were developed to deposit HA on bio-inert substrate, including ion beam sputtering, sol–gel, electrophoretic deposition, pulsed laser deposition, plasma spraying and electrochemical deposition. Here, we propose a new fabrication process that permits to obtain brushite and brushite/hydroxyapatite, that is a very simple and low cost. Brushite is dicalcium phosphate dihydrate (BS, CaHPO4·2H2O) that, when placed in simulated body fluid (SBF, knowed as Hank’s solution), it converts into hydroxyapatite. In particular, brushite and brushite/hydroxyapatite coatings were deposited on 316LSS from a solution containing Ca(NO3)2·4H2O and NH4H2PO4 through a displacement reaction based on a galvanic contact between 316LSS and a sheet of zinc that acts as sacrificial anode. Driving force for the cementation reaction arises from the difference in the electrochemical standard potentials of 316LSS and Zn that were immersed in the electrolyte. This process allows to deposit Brushite/Hydroxyapatite coatings without power supply. Samples were obtained varying deposition time (24 hours, 72 h and 108 h) and temperature (6 °C, 25 °C and 50 °C). SEM, EDS, Raman and XRD were used to full characterized the coatings. SEM images showed that the morphology changes as the temperature increases passing by a spherical dispersed structure, for films obtained from a 6 °C and 25 °C, to a tetrahedral and more compact structure, in the case of the film obtained at 50 °C. Through EDS the chemical composition of coatings was identified, calculating the Ca/P ratio, to obtain the stoichiometry, and the Ca/Fe ratio, to estimate the degree of coverage of the substrate. The temperature increase allows to obtain a uniform coating with a Ca/P ratio close to the optimal value (1.67), and a very high value of Ca/Fe ratio that obviously implies the formation of a very thick coating on the substrate. By Raman spectroscopy and X-ray diffraction (XRD) the phases were identified and the characteristic peaks of BS and BS/HA were found. Besides, corrosion (open circuit potential, potentiodynamic polarization and impedence measurement) and biocompatibility (cytotoxicity assays with osteoblastic cell) test were performed. Here, we will show that galvanic deposition is an advantageous method because is able to produce BS and BS/HA coatings that enhance the corrosion and biological properties of the 316LSS substrate.

In the field of water-alkaline electrolyzer, the develop of nanoporous nickel electrodes with low cost and high electrocatalysis efficiency is one of the potential approaches to increase their performance [1]. To obtain nanostructured electrodes, a facile approach is that of template electrosynthesis. With this method we have obtained electrodes made of nanowires of Ni that have a very high surface area. These electrode were obtained by a two-step procedure allowing to obtain an ordered array of Ni nanowires that completely covering the surface of current collector made of the same material. Besides, by amperostatic deposition we have covered these electrode with nanoparticles of IrO2 electrocatalyst. In this work, the results on the growth and characterization of these nanostructured electrode will be presented and discussed. Ni NWs were obtained by pulsed potential deposition into polycarbonate membranes [2]. IrO2 electrocatalyst was deposited on Ni NWs by different electrochemical techniques, like cyclic voltammetry and potentiostatic deposition [3]. For comparison, IrO2 electrocatalyst was also deposited on a Ni flat substrate. All electrodes were characterized by SEM, EDS, and XRD analyses. Moreover, the preliminary test on the electrochemical performances, carried out at constant current in 1M aqueous solution of potassium hydroxide, will be also reported. [1] D. Pletcher, X. Li Intern. J. Hydrogen energy 36 (2011) 15089. [2] R. Inguanta, S. Piazza, C. Sunseri Electrochem. Acta 53 (2008) 5766. [3] E. Ahlberg, P. Steegstra Electrochem. Acta 68 (2012) 206.

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.

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).

In this work, we present the performance of nanostructured array of Pd (Pd-NWs) for electrochemical sensors of hydrogen peroxide. Hydrogen peroxide is widely used in several fields, because to its oxidizing and reducing properties, like for treatment of waste water, paper and contaminated soils, as reagent in many chemical industries or like rocket propellant [1]. Furthermore, its presence or absence may be connected with many neurological deseases or/and with cancer [2].Today the most used methods for detection of that chemical are IR spectroscopy, spectrophotometry, fluorimetry, chemioluminescence and redox titration. However these methods are often uneconomical, have very high detection time or requires highly skilled staff [3]. On the other hand electrochemical tequiniques are very cheap, have a response time less than 5 seconds and not require any qualified staff. The electrochemical reduction of H2O2 on the electrode surfaces requires the absorption of a hydroxyl group on the surface of the sensor [4], consequently, performance of the sensor will be improved by a greater electrochemical active area. Thus, the use of nanostructures, such as nanowires, nanotubes or nanoparticles, allows to improve considerably the performance of the sensor because of their very high surface area, that is 70 times grater than geometric one. Most studies about electrochemical sensing of H2O2 have examined biological materials like protein or enzymes but, despite being highly selective, these biosensors have a very short lifetime and so are therefore uninteresting [3]. Most of the scientific research in this area is focused on transition metals or metal oxide and in particular on metal/metal oxide nanostructure, like nanoparticles, nanowire and nanotubes [5]. Guangdi Nie et al [6] has shown that Pd nanoparticles exhibit very good catalytic proprieties and stability towars H2O2 reduction. For this reason here we describe a simple, fast and cheap method for the detection of H2O2 based on an ordered arrays of Pd nanowire that exhibit a very large area respect Pd nanoparticles and so it should show higher electrocatalytic properties. Nanostructured sensors are obtained by template synthesis in commercial polycarbonate membranes. Arrays of Pd nanowires were fabricated through a displacement deposition reaction that permits to obtain nanostructures directly, very stable mechanically, and without the use of an external power supply. The morphology and the composition of Pd-NWs was monitored by SEM and energy-dispersive X-ray spectroscopy (EDX). The electrochemical properties of these sensors were characterized by ciclicvoltammetry and cronoamperometry. 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. These electrodes showed a stable and sensitive response towards H2O2 with a wide linear dependence over H2O2 concentration from 50 μM to 4400 μM and LOD of 15 μM and a good stability, greater than 1 month. These results imply thant the proposed electrodes could be successfully used as electrochemical sensor for hydrogen peroxide. [1]A nonenzymatic hydrogen peroxide sensor based on Au–Ag nanotubes and chitosan film ; Xueqin Li, Lisha Wang, Qi Wu,Zhichun Chen, Xianfu Lin [2] Silver nanowire array sensor for sensitive and rapid detection of H2O2E. Kurowska, A. Brz ́ozka, M. Jarosz, G.D. Sulka, M. Jaskuła [3] Elettrodi modificati per lo sviluppo di sensori elettrochimici, Università degli Studi di Bologna, Facoltà di Chimica Industriale, Lorella Guadagnini, Giuliano Longoni, Domenica Tonelli [4] Carbon nanodots as reductant and stabilizer for one-pot sonochemical synthesis of amorphous carbon-supported silver nanoparticles for electrochemical nanenzymatic H2O2 sensing [5] Facile preparation of MnO2nanotubes/reduced graphene oxidenanocomposite for electrochemical sensing of hydrogen peroxide M.R. Mahmoudiana,b, Y. Aliasa, W.J. Basiruna,c, Pei Meng Woia, M. Sookhakianda Department [6] Sacrificial template-assisted fabrication of palladium hollow nanocubes and their application in electrochemical detection towards hydrogen peroxide Guangdi Nie Xiaofeng Lu Junyu Lei Liu Yang Xiujie Bian Yan Tong Ce Wang

The accumulation of energy by batteries plays a fundamental role for the production of electrical energy and for its efficient management. Between different storage systems the lithium-ion battery are considered very interesting. Although they are now a well-established commercial reality, they are still subject of vigorous research efforts, in order to make improvements primarily in terms of costs, safety and energy density. The latter is in fact still low compared to that of fossil fuels, if you think to the automotive field. In particular efforts are focused towards the identification of valid alternatives to the electrode materials so as to overcome the limitations and extend the use of these batteries in the applications of interest for the future. The purpose of this work is consisted in the synthesis and characterization of an anode material innovative, the hydroxy-lead chloride (PbOHCl) innanostructured shape. The idea of synthesizing the above compound comes from the results recently published by Shu et al [1] that in order to improve the performance of the anodes made from Pb for lithium-ion batteries have proposed the use of PbOHCl. In fact, Pb based material anode although have shown clear advantages in terms of capacity attained and economy, still have limitations related to the low cyclability, that can be improved by the introduction hydroxyl and chloride functional groups. In this way it is possible to achieve a theoretical capacity of about 661 mAh/g. In this work to improve the electrochemical performance, this compound was obtained in the shape of nanowires. This is a key point because the nanostructures, in addition to ensure a very high surface area with a higher utilization of the active material and therefore a higher specific energy, thanks to their small size allow to better absorb the mechanical stresses associated with the volume expansion avoiding the pulverization on the anode. Furthermore, the use of the nanostructures would improve the kinetics of the electrode reactions because increase the rate of insertion / extraction of Li due to less diffusion path and ensure a higher rate of electron transfer. In particular we have developed a innovative fabrication procedure that permit to obtain directly in the channels of a nonporous template the PbOHCl compound by a galvanic process. Here the preliminary results will be showed. [1] J. Shu et al, Electrochimica Acta, 2013, 102, 381-387.

A metal displacement reaction has been used in order to cause precipitation of oxide nanostructures within pores of anodic alumina membrane (AAM) templates. Here, we focus on the displacement deposition of LnO/OH (Ln = La, Ce, Sm, Er) nanostructures using Zn as sacrificial anode, employing a specific cell arrangement where a galvanic couple was formed between zinc anode and the Au thin layer covering template pore bottom. Progress of displacement deposition reaction into template channels was monitored measuring the open circuit potential as well as pH changes of the electrolyte. A progressive de-activation of the anode surface was observed for long deposition times, caused by deposition of passivating oxides on the anodic area. Deposited LnO/OH oxides were investigated by energy dispersion spectroscopy, X-ray diffraction, scanning electron microscopy and Raman spectroscopy. Morphological characterisation revealed that at room temperature a mixed wire/tubular structure was obtained in the case of La and Sm, whilst only tubular structure was observed for Ce and Er.

CZTS thin films were obtained by one-step electrochemical deposition from aqueoussolution at room temperature. Films were deposited on two different substrates, ITOon PET, and electropolished Mo. Differently from previous studies focusing exclu‐sively on the formation of kesterite (Cu4ZnSnS4), here, the synthesis of a phase withthis exact composition was not considered as the unique objective. Really, startingfrom different baths, amorphous semiconducting layers containing copper–zinc–tin–sulphur with atomic fraction Cu0.592Zn0.124Sn0.063S0.221 and Cu0.415Zn0.061Sn0.349S0.175, werepotentiostatically deposited. Due to the amorphous nature, it was not possible to de‐tect if one or more phases were formed. By photoelectrochemical measurements, weevaluated optical gap values between 1.5 eV, similar to that assigned to kesterite, and1.0 eV. Reproducibility and adhesion to the substrate were solved by changing S withSe. Preliminary results showed that an amorphous p-type layer, having atomic frac‐tion Cu0.434Zn0.036Sn0.138Se0.392and an optical gap of 1.33 eV, can be obtained by one-stepelectrochemical deposition.

Ruthenium oxide nanotubes were fabricated by a single-step galvanostatic deposition using porous anodic alumina membrane as template. For the electrodeposition process, we used a electrochemical cell specifically designed in order to employ only 0.5 ml of 0.02 M RuCl3•xH2O solution. The deposition from a very small volume was specifically addressed owing to the high cost of ruthenium compounds, which could be of some relevance from an applicative point of view. Several techniques were used to characterize the samples prior to and after thermal treatment, which was carried out at different temperatures in order to study the crystallization process of the deposit. Raman spectroscopy of as-deposited nanotubes revealed the presence of RuO2 vibrating modes, while XRD patterns did not show RuO2 peaks, consequently the formation of a subnano-crystalline structure was proposed. After thermal treatment at different temperature above 600°C, they crystallized in the tetragonal form of RuO2. Both XRD analysis and Raman spectroscopy revealed that crystal size of the deposit grew with temperature up to 1000°C. SEM investigations showed the formation of nanotubes having an uniform average external diameter, while wall thickness changed throughout the height.

This work shows that it is possible to obtain self-standing Pd nanowires into anodic alumina membranes by a simple metal displacement deposition. By using a proper arrangement, specifically designed in order to optimize the process, polycrystalline Pd nanowires were deposited from a solution containing Pd(NH3)4(NO3)2 as precursor. Morphological analysis showed the formation of perfectly aligned nanowires with a uniform diameter throughout the entire length. This last parameter was controlled by both the deposition time and the ratio between the anodic area (active metal) and the cathodic area (pore bottom). Keywords: Displacement deposition, Template synthesis, Palladium nanowires, Alumina membranes

The anodic behaviour of cast Ti–Mo alloys, having different Mo contents (6–20 wt.%), was investigated in acidic and neutral aerated aqueous solutions. All sample showed a valve-metal behaviour, owing to formation and thickening of barrier-type anodic oxides displaying interference colours. Growth kinetics of passive films is influenced by both anodizing electrolyte and composition of the starting alloy. This last parameter was found to change also the solid-state properties of the films, explored by photoelectrochemical and impedance spectroscopy experiments. Thicker films ( U f = 8 V/MSE) grown on alloys richer in Mo showed more resistive character and a photocurrent sign inversion under negative bias, that revealed an insulating character, whereas corresponding films grown on alloys with lower Mo content, as well as thinner films, behaved as n-type semiconductors. Results are discussed in terms of formation of a mixed Ti–Mo oxide phase.

Different Ni nanostructure arrays were fabricated by pulsed electrodeposition from a Watts bath inside the pores of anodic alumina membrane (AAM) templates. Under a trapezoidal waveform of potential, consisting of fast linear sweeps between 0 and −3 V (SCE) interleaved by delay times at 0 (10 s) and −3 V (0.1 s), Ni nanowires were grown. The rate of nanowires growth was constant up to 60 min of deposition. For longer times, the growth of nanowires was not uniform, and after about 180 min some nanowires reached the template surface exposed to the electrolyte. Under square potential pulses between the same potentials (pulse length 1 s), nanotubes of Ni are obtained. Morphological analysis of these nanostructures at different lengths revealed that the inner profile of nanotubes evolved from cylindrical to conical with increasing deposition time. The possibility to grow either nanowires or nanotubes in dependence of the potential waveform, as well as the growth rate of nanostructures were discussed taking into account the reaction of hydrogen evolution, occurring simultaneously with Ni electrodeposition.

The influence of experimental parameters on the morphology of the porous structure and on the formation kinetics has been investigated for anodic alumina membranes (AAM) grown in aqueous H 3 PO 4 at 160 V. It was found that pore aspect ratio and membrane porosity on the solution-side surface are influenced by tensiostatic charge, bath temperature and the presence of Al 3+ ions in solution. Morphological and kinetic data, recorded in different conditions, give useful information on the growth mechanism of pore channels in phosphoric acid solution. Nickel nano-structures have been fabricated using AAM as template. Electroless deposition, performed by adding the reducing agent to a suitable bath in several steps, resulted in the formation of short metal nanotubes (about 5 μm long) in the upper part of the channels. Long Ni nanowires (up to 25 μm) with aspect ratio higher than 100 were obtained by pulsed unipolar electrodeposition from a Watt bath. In this case, both the influence of some experimental parameters on the nanowires growth and the fast current transients during the electrodeposition steps were analyzed.

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 counterelectrode 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. Copyright © 2015, AIDIC Servizi S.r.l.

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 á-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. hí plot, whose extrapolation to Iph=0 gives optical gaps values of 2.5 and 3.2 eV, which are typical of MoO2 and á-MoO3, respectively. In addition, photoelectrochemical investigation revealed n-type conductivity of this mixed oxide deposit. Copyright © 2015, AIDIC Servizi S.r.l.

Anodic films were grown potentiodynamically in different electrolytes (pH = 1–14) on a Ti–50Zr at% cast alloy, obtained by fusion in a voltaic arc under argon atmosphere. The thickness of the films was varied by changing formation potential from the open circuit potential up to about 9 V; growth was followed by 30 min stabilization at the forming potential. Films having different thicknesses were characterized by photocurrent spectroscopy (PCS) and electrochemical impedance spectroscopy (EIS). Moreover, film composition was analyzed by X-ray photoelectron spectroscopy (XPS). Regardless of the anodizing conditions, passive films on the Ti–50Zr at% alloy consist of a single layer mixed oxide phase containing both TiO 2 and ZrO 2 groups. However, an enrichment of Ti within the passive film, increasing with the film thickness, is detected both by PCS and XPS. This leads to concentration profiles of Ti 4+ and Zr 4+ ions along the thickness, and to different electronic properties of very thin films (more insulating) with respect to thicker films (more semiconducting), as revealed by the photocurrent–potential curves.

PbO2 nanowires were obtained by template electrodeposition in polycarbonate membranes and tested as positive electrode for lead-acid battery. Nanowires were grown on the same material acting as current collector that was electrodeposited too. The nanostructured electrodes were assembled in a zero-gap configuration using commercial negative plate and separator. Cell performance was tested by galvanostatic charge/discharge cycles in a 5 M H2SO4 aqueous electrolyte. PbO2 nanostructured electrodes were able to deliver at 1C rate an almost constant capacity of about 190 mAh g−1 (85% of active material utilization), close to the theoretical value (224 mAh g−1). The nanowire array provides a very large surface area (about 70 times higher than the geometrical one) that enhances the specific capacity of the battery. SEM images of the as-prepared and cycled electrodes showed that nanowires morphology changes significantly after the initial cycles. Change of morphology led to the formation of very spongy structure, characterized by the presence of macro-voids, which ensured penetration of the electrolyte in the inner areas of the electrode. Besides, PbO2 nanowires showed a very good cycling stability, maintained for more than 1000 cycles. These findings indicate that this new type of electrode might be a promising substitute of positive plates in lead-acid battery.

Electrodeposition is a convenient technique for the development of low cost materials for photovoltaic (PV) device processing. Using a single step electrodeposition route, several groups have fabricated CIS (CuInSe) and CIGS (CuInGaSe) films. One of the most important requirements for successful application of one-step electrodeposition film formation is the ability to control composition of the deposited films and to develop polycrystalline microstructures with a low surface roughness and high sintered density.

This work is aimed at studying the growing process of nanostructures electrodeposited from molybdate aqueous solutions at different pH values into pores of polycarbonate membrane templates. The challenging issue was the opportunity to investigate a rather complex deposition process in a confined ambient, where electrochemical conditions are quite different from those usually established for deposition on a flat substrate. Nanostructures were grown from a bath containing Mo7O246– (NH4)6Mo7O24·4H2O) at different concentrations (50–100 g/L), at a constant cathodic current density of 2 mA/cm2 (electrodeposition area ∼8 cm2). Nanostructured deposit was characterized by XRD, EDS, Raman, XPS, and photoelectrochemical spectroscopy. Several parameters have been investigated, such as electrodeposition time, concentration of Mo precursor, and pH. These parameters do not influence the nature of deposit that always consists of mixed valence molybdenum oxides, whereas the nanostructure morphology changes with pH. Nanos...

Electrodeposition is a convenient technique for the development of low cost materials for photovoltaic (PV) device processing. Using a single step electrodeposition route, several groups have fabricated CIS (CuInSe) and CIGS (CuInGaSe) films [1]. One of the most important requirements for successful application of one-step electrodeposition film formation, is the ability to control composition of the deposited films and to develop polycrystalline microstructures with a low surface roughness and high sintered density. In this preliminary work, CIS films were produced by single bath electrodeposition finding the optimal conditions in order to achieve a dense film with high crystallinity and uniform, flat surfaces, which are of critical importance for photovoltaic applications. Electrodeposition was carried out in the potentiostatic mode using a conventional three-electrode configuration.

In this work, we report some preliminary results concerning the fabrication of quaternary semiconductor Cu2ZnSnS4 (CZTS) thin films on a flexible substrate through the simultaneous electrodeposition of elements having different standard electrochemical potentials. CZTS thin films were obtained by potentiostatic deposition from aqueous baths at room temperature and under N2 atmosphere, varying bath composition. Chemical composition and structure of the electrodeposited films were evaluated by EDS, SEM, RAMAN and XRD. Preliminary results on the photoelectrochemical behaviour of the films will be also presented.

n 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. Copyright © 2013, AIDIC Servizi S.r.l.

Solar cells based on semiconductor thin films are emerging as alternative to silicon;however,the materials giving the highest efficiency,CdTe and CuInGaSe,contain toxic (Cd) and rare (In) elements.In this field,the challenge is to substitute In and Cd with abundant and non-toxic elements without lowering the high efficiency achieved with these technologies.Compounds based on copper,zinc,tin and sulfur (CZTS) are potentially promising materials,because they present all the above listed features.Among the different methods to obtain CZTS,the electrochemical route appears of great interest because easy to conduct.Up to date,the literature shows that non-uniformity in composition and/or the presence of secondary phases prevent the obtainment of electrochemical CZTS thin-film of high quality.In this paper,we present the principal results of an extensive investigations conducted in order to find suitable conditions for growing CZTS thin films with good performance through the simultaneous electrodeposition of elements having different standard electrochemical potentials.Thin films were obtained on a flexible substrate by potentiostatic deposition from aqueous baths by changing different deposition parameters (bath composition and temperature,deposition time).Chemical composition and structure of the electrodeposited films were evaluated by EDS,SEM,RAMAN and XRD.Preliminary results on the photoelectrochemical behaviour of the films will be also presented.