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This preliminary work shows a new and innovative way to produce laser scribed reduced graphene oxide (LSGO) electrodes using different porous substrates (ranging from paper to plastic and fabric). The obtained electrodes were also tested as electrochemical sensors towards the detection of phosphate ions in water. To obtain the electrodes, a water suspension of GO was filtered on top of substrate (such as Whatman® filter paper) and a complete sensor was obtained from its reduction using a CO2 laser. The electrode is composed of working and counter electrodes made of LSGO and a reference electrode of a Ag/AgCl obtained by using a commercial AgCl conductive paste. Phosphate ions were detected by exploiting the reaction between molybdate and phosphate ions in acidic media (known in literature as molybdenum blue method). This chemical reaction produces the Keggin-type complex (PMo12O40)3-, that can be reduced under applied potential. The obtained results show that phosphate ions can be detected in a wide linear range, from 0.001 mM to 1mM, in presence of 1mM molybdate with a very satisfying selectivity. We also tried to pre-treatment the paper substrate with acidic molybdate ions in order to obtain a ready-made sensor directly usable for the detection of phosphate ions in situ avoiding any kind of real sample manipulation For this aim, the paper substrate was soaked with sulphuric acid and molybdate solution and dried in order to desorb these chemicals directly into the water sample to be analyzed. Preliminary results, shows that the process of absorption and desorption can be carried out by optimizing the volume and concentration of the absorbed solution and thus can be used to obtain a portable, easy to use and fast phosphate sensor for in situ and real time monitoring of water quality.

The galvanic deposition method was used to deposit Hydroxyapatite/Chitosan/Collagen coatings on 304 stainless steel. Galvanic deposition is an alternative and valid way to fabricate bio-coatings with high biocompatibility and good anticorrosion properties. Physical-chemical characterizations were carried out to investigate chemical composition and morphology of the samples. Coatings consist of a mixture of calcium phosphate (Brushite and Hydroxyapatite) with chitosan and collagen. Corrosion tests were performed in the simulated body fluid (SBF) after different aging times. Results show that, in comparison with bare 304 stainless steel, coating shifts corrosion potential to anodic values and reduces corrosion current density. Nevertheless, the aging in SBF led to a completely conversion of brushite into hydroxyapatite. The release of metal ions, measured after 21 days of aging in SBF solution, is very low due to the presence of coating that slow-down the corrosion rate of steel.

In this work, an electrochemical sensor for uric acid determination is shown with a preliminary study for its validation in real samples (milk and urine). Uric acid can be electrochemically oxidized in aqueous solutions and thus it is possible to obtain electrochemical sensors for this chemical by means of this electrooxidation reaction. Indium tin oxide coated on flexible polyethylene terephthalate substrate, modified with reduced graphene oxide and gold nanoparticles by co-electrodeposition, was used. Electrodeposition was performed at -0.8V vs SCE for 200 s. All samples were characterized by electron scan microscopy and electron diffraction spectroscopy. A careful investigation on the effect of pH was performed to understand its influence on uric acid oxidation. The detection of uric acid was using the linear sweep voltammetry. Results show that the peak current increases linearly with uric acid concentration from 10 to 1000 μM with a limit of detection of about 7.1 μM. The sensor shows high selectivity towards different interferents that can be found in the milk and urine matrix, such as chloride, calcium, sodium and ammonium ions. To prove the applicability of the proposed sensor, uric acid was quantified in real milk and urine samples with excellent results comparable to those of conventional techniques.

Aim of this work is to develop a new nano-structured and nano-composite lead acid negative electrode with reduced graphene oxide (rGO). Nanostructured electrodes are fabricated by template electrodeposition of lead nanowires on a lead current collector. A polycarbonate track-etched membrane was used as a template (200 nm mean pores diameter). rGO was deposited on the nanostructured electrode from a graphene oxide (GO) dispersion in acetate buffer solution (ABS) (0.2 g/L). Potentiostatic deposition of rGO at -0.8 V vs. standard calomel electrode (SCE) was performed. Electrode with rGO was tested as negative electrode in cell with 5M sulfuric acid solution, a commercial pasted positive plate, as counter-electrode, and an AGM separator. The electrodes well performed at 2C-rate in deep cycling tests (cut off cell voltage 1.2 V). Its capacity grew during cycling test and reached 232.9 mAh/g, which corresponds to a degree of active material utilization of 90%. Its faradaic efficiency reached 90%. Electrodes with similar morphology were obtained treating the electrodes with a HNO3 solution at -0.8 V vs SCE or with a dispersion of GO in HNO3. These electrodes showed lower active material utilization and lower faradaic efficiency.

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.

Template electrosynthesis is a facile and cheap approach for obtaining nanostructures with very high surface area. This fabrication method has been used to produce electrodes for different applications, among which the electrolysis. In previous works, Ni and IrO2 nanostructured electrodes were tested for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline solution, respectively, without and with addition of Pd nanoparticles. In this work, Ni-Co alloy electrodes were fabricated by the same method, starting from a bath containing a mixture of Ni and Co. After fabrication of the nanostructures and template dissolution, electrodes were characterized by EDS and SEM. The results show that i) alloy deposition is possible by this method, and ii) alloy is richer in Co compared to the composition of the bath employed for deposition. In order to evaluate the electrocatalytic properties of Ni-Co electrode, electrochemical tests were performed and the results were compared with pure Ni and Co electrodes. The tests were conducted through either cyclic or linear sweep voltammetry in 30% w/w KOH aqueous solution at room temperature. For the HER, pure Ni electrode was found to be more performing. Whereas, with regard to the OER, performance of the nanostructured Ni-Co electrodes show an improvement more than 20% in terms of electrocatalysis, in comparison with pure Ni and Co electrodes.

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 recent years, the storage of energy produced by renewable sources has become a topic of great interest. Lead-acid batteries are widely used in this field, in particular those based on VRLA (Valve-Regulated-Lead Acid) technology, in which the electrolyte is immobilized inside the battery. In this paper, the use of a hydrogel as an electrolyte was considered. Hydrogel can be described as a three-dimensional network of a hydrophilic polymer that can absorb large amounts of water (or aqueous solutions) without dissolving. Pb and PbO2 nanostructured electrodes were used in the battery that used hydrogel as an electrolyte. Two different types of hydrogels were synthesised, both based on PVA that is a biodegradable, biocompatible, non-toxic, and non-carcinogenic polymer. The first one was obtained through physical gelling, the second one was obtained using borax (sodium tetraborate decahydrate) as a cross-linking agent. Preliminary tests of nanostructured lead-acid batteries using both types of hydrogels as an electrolyte were conducted for 100 cycles at 1C. The physically gelled hydrogel gave the best results in terms of efficiency, likely, owing to its greater absorption capacity. It was also verified that the recombination of the gases evolved during the charge phase (hydrogen and oxygen) takes place inside the battery itself. This is the major advantage of the gelled electrolyte in comparison with the liquid one.

In this work, electrodes based on laser-scribed reduced graphene oxide were fabricated using filter paper as the substrate. To fabricate the electrodes, a water suspension of graphene oxide was filtered to produce a continuous and uniform film of graphene oxide on the filter paper surface. Subsequently, a CO2 laser was used to "write" the working, counter and reference eelctroes by reducing graphene oxide in specific areas to define complete sensors. Referecnce electrodes were then coated with a commercial Ag/AgCl conductive paste to produce a quasi Ag/AgCl reference. As fabricated devices were employed as electrochemical sensors for detection of phosphate ions in water by employing the molybdenum blue method. This method exploits the reaction between molybdate and phosphate ions in acidic media leading to a Keggin-type complex (PMo12O3 40) which, being electrochemically active, enables the indiret detection of phosphate ions. Sensors exhibited high selectivity and sensitive detection of phosphate ions in a wide linear range, from 1 to 20 & mu;M; with a limit of detection of 0.4 & mu;M. To demonstrate that sensors could be utilized for in-situ phosphate ion detection, paper substrate was first pre-loaded with sul-phuric acid and molybdate ions. During analysis, these chemicals were then desorbed directly into the test sample eliminating the need for any kind of external manipulation or reagent addition. Thus, this paper presents the fabrication of a portable, easy-to-use, biodegradable and fast phosphate ions sensor for in situ and real-time monitoring of water quality.

Over the last decade, as a consequence of the global decarbonization process, the interest towards green hydrogen production has drastically increased. In particular a substantial research effort has focused on the efficient and affordable production of carbon-free hydrogen production processes. In this context, the development of more efficient electrolyzers with low-cost electrode/electrocatalyst materials can play a key role. This work, investigates the fabrication of electrodes of nickel-zinc alloys with nanowires morphology cathode for alkaline electrolyzers. Electrodes are obtained by the simple method of template electrosynthesis that is also inexpensive and easily scalable. Through the analysis of the morphological and chemical composition of nanowires, it was found that the nanowires composition is dependent on the concentration of two metals in the deposition solution. Electrocatalytic tests were performed in 30% w/w potassium hydroxide aqueous solution at room temperature. In order to study the electrodes stability, mid-term galvanostatic test was also carried out. All electrochemical tests show that nanowires with about 44.4% of zinc have the best performances. Particularly, at −50 mAcm−2, these electrodes have an overpotential 50 mV lower than pure Ni nanowire. NiZn nanowires show also a good stability over time without noticeable signs of performance decay.

The performance of electrochemical sensors using an in situ pH control technique for detection of mercury and copper in neutral solutions is described herein. Sensors are comprised of two distinct parallel gold interdigitated microband electrodes each of which may be polarised separately. Biasing one interdigitated “protonator” electrode sufficiently positive to begin water electrolysis, resulted in the production of H+ ions, which, consequently droped the interfacial pH at the other second interdigitated “sensing” electrode. This decrease in pH permitted the electrodeposition (and consequent stripping) of metals at a sensing electrode without the need to acidify the whole test solution. In this work, the local pH could be adjusted in the acidic pH range in a stable and reproducible way just by tailoring the polarization of the protonator electrode. Using this approach, a linear range for copper 5 to 100 ppb and for mercury 1 to 75 ppb were obtained. The sensors also have an extremely high sensitivity for the metals. The in-situ pH control, coupled with electrochemical stripping, allowed metal detection in a complex water matrix, e.g., river water without the need for sample pre-treatment. The electrochemical results were confirmed by comparison to those obtained using inductively coupled plasma – optical emission spectroscopy. A very good agreement was observed between both sets of results. The electrode reproducibility was high (RSD < 10%) and the metals could be co-detected simultaneously. Thus, this work shows a fast and easy approach for in-situ pH control for multi metal detection using solid state sensors.

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 fabrication and characterization of nickel-alloy electrodes for alkaline electrolysers is reported. Three different alloys (Ni–Co, Ni–Zn and Ni–W) at different composition were studied in order to determine the optimum condition. Nanostructured electrodes were obtained by template electrodeposition into a nanoporous membrane, starting from aqueous solution containing the two elements of the alloy at different concentrations. Composition of alloys can be tuned by electrolyte composition and also depends on the difference of the redox potential of elements and on the presence of complexing agents in deposition bath. Electrochemical and electrocatalytic tests, aimed at establishing the best alloy composition, were carried out for hydrogen evolution reaction. Then, test conducted at a constant current density in potassium hydroxide (30% w/w) aqueous solution were also performed. For all investigated alloys, very encouraging results were obtained and in particular Ni–Co alloys richer in Co showed the best performance.

Nanostructured Pb electrodes consisting of nanowire arrays were obtained by electrodeposition, to be used as negative electrodes for lead–acid batteries. Reduced graphene oxide was added to improve their performances. This was achieved via the electrochemical reduction of graphene oxide directly on the surface of nanowire arrays. The electrodes with and without reduced graphene oxide were tested in a 5 M sulfuric acid solution using a commercial pasted positive plate and an absorbed glass mat separator in a zero-gap configuration. The electrodes were tested in deep cycling conditions with a very low cut-off potential. Charge–discharge tests were performed at 5C. The electrode with reduced graphene oxide outperformed the electrode without reduced graphene oxide, as it was able to work with a very high utilization of active mass and efficiency. A specific capacity of 258 mAhg−1–very close to the theoretical one–was achieved, and the electrode lasted for more than 1000 cycles. On the other hand, the electrode without reduced graphene oxide achieved a capacity close to 230 mAhg−1, which corresponds to a 90% of utilization of active mass.

The water distribution network (WDN) is subject to water leakages due to pipes breaking, which induces a wastage of water and overconsumption of power for pumps. Leakages are directly related to pressure in the pipes. To reduce leakages, pressure reducing valves (PRV) are installed in water distribution networks to reduce pressure in the pipes. However, pressure reduction induces a loss of energy which is wasted within the PRV. To recover a part of this energy, pressure reducing valves can be replaced by using pumps as turbines (PATs). Since head and flow rates are variable in the WDN, it is necessary to regulate the PAT, which does not function properly under variable upstream conditions. In this paper, the hydraulic regulation (HR) and hydraulic-electric regulation (HER) methods are studied in economic and energy production terms. A comparison between HR and HER is based on results from two real sites. The study is carried out using an innovative decision-support algorithm, which is described in detail. The results show that adding electrical regulation improves energy production, but the increase in installation costs makes the sites less economically viable.