Copper nanowires as higly sensitivite electrode for nitrate ions in water

Agricultural and livestock sectors are the main sources of nitrate ions contamination in water and foodstuff. [1]. High nitrate concentration is dangerous for both environment (algae overgrowth) and human health. Nitrate ions can be converted in different harmful nitrogen based compound such as NO2-, NO, N-nitroso compounds [2] that are responsible of several diseases such as cancer, Parkinson [3-4]. For these reasons, the Environmental Protection Agency, has established the maximum amount of nitrate ions in drinkable water at 44 mg/l, limit that is valid in many European countries [5]. Generally, spectroscopy techniques are the most used because allow to carry out analyses with high precis…

Ni alloy nanowires for alkaline electrolysers

In recent years, the interest towards green hydrogen has drastically increased due to the global decarbonization process. Green hydrogen is obtained by water electrolysis using only electricity from renewable sources. It is considered one of the best storage systems in terms of environmental sustainability but not in economic ones. Nowadays, the research is focused on improving the Alkaline Water Electrolysis (AE) to reduce the cost of production. An approach to improve AE performance is based on nanostructured electrodes characterized by high electrocatalytic activity due to the very high surface area. In fact, the development of more efficient electrolysers with low-cost electrode-electro…

Reduced graphene oxide decorated with metals nanoparticles electrode as electrochemical sensor for dopamine

Dopamine (DA) is one of the most important neurotransmitters that influences the processes that involve memory, sleep, mood, learning among others [1]. In fact, in the last years, dopamine concentration in human body fluids has been related to some neurodegenerative diseases, such as Parkinson and Alzheimer's diseases [2]. The possibility to have a bio-marker for these disease is of extreme importance because, disease related with dementia, are diagnosed when they are already developed and their management become almost impossible. The possibility to continuously monitor DA level in fluids, such as blood and urine, could accelerate the early diagnosis of these diseases. The principal analyt…

ELECTROCHEMICAL H2O2 SENSORS BASED ON Pd and Cu NANOSTRUCUTERS

In the last decades, with the fast improvement of electronics, the field of sensors is highly expanding. The basic idea of sensors is to detect something and then trigger a corresponding action. This simple, but very important, concept can be used in different fields: from chemical industries to farms, from the environmental monitoring [1] to a point of care analysis [2]. Currently, talking about sensing of chemical species, different techniques are used, such as Atomic Absorption Spectroscopy (AAS), Graphite Furnace Atomic Absorption Spectroscopy (GFAAS), Inductively Coupled Plasma Mass Spectroscopy (ICP-MS), IR spectroscopy, redox titration and so on. Despite they are highly efficient in …

Nanostructured Based Electrochemical Sensors.

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…

CaP-Bioglass composite coating by galvanic deposition

Orthopedic devices are increasingly used in our life to improve the health of patients after bone fractures due to accidents, aging, or sports injuries. Metallic materials (i.e. stainless steel, titanium alloys chromium alloys) are widely employed to fabricate prostheses, screws, and osteosynthesis plates. Although metals could be good mechanical properties like human bone, corrosion phenomena could occur, causing in the worst cases the failure of orthopedic implants. In addition, metal ions released around periprosthetic tissues could arise allergenic and cancerogenic effects. Nowadays, the research was focused on coating science to deal with these issues. In particular, the development of…

Electrodeposited nickel–zinc alloy nanostructured electrodes for alkaline electrolyzer

Abstract 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.…

Controlled solution-based fabrication of perovskite thin films directly on conductive substrate

Abstract 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 an…

Pd-Co-Based Electrodes for Hydrogen Production by Water Splitting in Acidic Media

To realize the benefits of a hydrogen economy, hydrogen must be produced cleanly, efficiently and affordably from renewable resources and, preferentially, close to the end-users. The goal is a sustainable cycle of hydrogen production and use: in the first stage of the cycle, hydrogen is produced from renewable resources and then used to feed a fuel cell. This cycle produces no pollution and no greenhouse gases. In this context, the development of electrolyzers producing high-purity hydrogen with a high efficiency and low cost is of great importance. Electrode materials play a fundamental role in influencing electrolyzer performances; consequently, in recent years considerable efforts have b…

Nanostructured nickel–zinc alloy electrodes for hydrogen evolution reaction in alkaline electrolyzer

PANI-Based Wearable Electrochemical Sensor for pH Sweat Monitoring

Nowadays, we are assisting in the exceptional growth in research relating to the development of wearable devices for sweat analysis. Sweat is a biofluid that contains useful health information and allows a non-invasive, continuous and comfortable collection. For this reason, it is an excellent biofluid for the detection of different analytes. In this work, electrochemical sensors based on polyaniline thin films deposited on the flexible substrate polyethylene terephthalate coated with indium tin oxide were studied. Polyaniline thin films were abstained by the potentiostatic deposition technique, applying a potential of +2 V vs. SCE for 90 s. To improve the sensor performance, the electronic…

Ascorbic Acid determination using linear sweep voltammetry on flexible electrode modified with gold nanoparticles and reduced graphene oxide

Indium tin oxide (ITO) coated on flexible polyethylene terephthalate (PET) substrate electrode was modified with reduced graphene oxide and gold nanoparticles by simple co-electrodeposition performed at -0.8 V vs SCE for 200 s. All samples were characterized by electron scan microscopy. The as prepared electrode was used as electrochemical sensor to selective detection of ascorbic acid using linear sweep voltammetry. Excellent results were obtained in a linear range from 20 to 150 µM of ascorbic acid with a limit of detection of about 3.1 µM (S/N=3.3). The sensors have a reproducibility of about 5.5% and also show high selectivity towards different interferents such as chlorine, calcium, ma…

Development of a nanostructured sensor for monitoring oxidative stress in living cells

Oxidative burden is elevated in the lung of COPD patients and is associated with aging and chronic inflammation. When overcoming physiological levels, reactive oxygen species (ROS) cause cell damage and sustain inflammation. Both lung epithelium and alveolar macrophages contribute to ROS generation. Currently, ROS generation is measured using fluorescent probes and colorimetric/fluorimetric assays. We present an amperometric nanostructured sensor for real-time detection of hydrogen peroxide (H2O2) released by living cells. The H2O2 sensing performance was evaluated through the current vs time response of platinum rod at a working potential of −0.45 V vs saturated calomel electrode acting as…

A simulation and experimental study of electrochemical pH control at gold interdigitated electrode arrays

Abstract In electroanalysis, solution pH is a critical parameter that often needs to be tailored and controlled for the detection of particular analytes. This is most commonly performed by the addition of chemicals, such as strong acids or bases. Electrochemical in-situ pH control offers the possibility for the local adjustment of pH at the point of detection, without the need for additional reagents. Finite element analysis (FEA) simulations have been performed on interdigitated electrodes, to guide experimental design in relation to both electroanalysis and in-situ control of solution pH. No previous model exists that describes the generation of protons at an interdigitated electrode arra…

Ni alloy nanowires as high efficiency electrode materials for alkaline electrolysers

Abstract 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 establishin…

Galvanic deposition of Chitosan-AgNPs as antibacterial coating

Thanks to mechanical properties similar human bones, metallic materials represent the best choice for fabrication of orthopedic implants. Although metals could be widely used in the field of biomedical implants, corrosion phenomena could occur, causing metal ions releasing around periprosthetic tissues leading, in the worst cases, to the development of infections. In these cases, patients need prolonged antibiotic therapies that may cause bacterial resistance. Preventing bacterial colonization of biomedical surfaces is the key to limiting the spread of infections. Antibacterial coatings have become a very active field of research, strongly stimulated by the increasing urgency of identifying…

FLEXIBLE ELECTRODE BASED ON GOLD NANOPARTICLES AND REDUCED GRAPHENE OXIDE FOR URIC ACID DETECTION USING LINEAR SWEEP VOLTAMMETRY

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 ef…

Electrochemical pH Control at Gold Nanowires

In this work, interdigitated arrays of nanowire electrodes are used with one array acting as the working electrode while the other is used to generate the required protons. Finite element simulations of the pH control electrodes were performed to provide insight on the generation and subsequent diffusion of protons. This informed the inter-tine spacing of the electrodes used.. This electrochemical pH control method was then used to enable the detection of analytes of interest.

High-Performance Lead-Acid Batteries Enabled by Pb and PbO2 Nanostructured Electrodes: Effect of Operating Temperature

Lead-acid batteries are now widely used for energy storage, as result of an established and reliable technology. In the last decade, several studies have been carried out to improve the performance of this type of batteries, with the main objective to replace the conventional plates with innovative electrodes with improved stability, increased capacity and a larger active surface. Such studies ultimately aim to improve the kinetics of electrochemical conversion reactions at the electrode-solution interface and to guarantee a good electrical continuity during the repeated charge/discharge cycles. To achieve these objectives, our contribution focuses on the employment of nanostructured electr…

Nanostructured Electrochemical Devices for Sensing, Energy Conversion and Storage

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 the…

Behavior of Calcium Phosphate–Chitosan–Collagen Composite Coating on AISI 304 for Orthopedic Applications

Calcium phosphate/chitosan/collagen composite coating on AISI 304 stainless steel was investigated. Coatings were realized by galvanic coupling that occurs without an external power supply because it begins with the coupling between two metals with different standard electrochemical potentials. The process consists of the co-deposition of the three components with the calcium phosphate crystals incorporated into the polymeric composite of chitosan and collagen. Physical-chemical characterizations of the samples were executed to evaluate morphology and chemical composition. Morphological analyses have shown that the surface of the stainless steel is covered by the deposit, which has a very r…

A direct comparison of 2D versus 3D diffusion analysis at nanowire electrodes: A finite element analysis and experimental study

In electroanalysis, the benefits accrued by miniaturisation are a key driver in sensor development. Finite element simulations of electrochemical processes occurring at ultramicro- and nano-electrodes are used to provide key insight into experimental design in relation to diffusion profiles and expected currents. The most commonly used method, the diffusion domain approach (DDA) offers a means of reducing a three dimensional design to two dimensions to ease computational demands. However, the DDA approach can be limited when using basic assumptions which can be incorrect, for example that all electrodes in an array are equivalent. Consequently, to get a more realistic view of molecular diff…

Comparison of 2D versus 3D diffusion analysis at Nanowire Electrodes: Finite element analysis and experimental study

In electroanalysis, finite element simulations of electrochemical processes occurring at electrodes are used to provide key insight into experimental design in relation to diffusion profiles and expected currents. The diffusion domain approach (DDA) offers a means of reducing a three dimensional design to two dimensions to ease computational demands. However, the DDA approach can be limited when basic assumptions, for example that all electrodes in an array are equivalent, are incorrect. Consequently, to get a more realistic view of molecular diffusion to nanoelectrodes, it is necessary to undertake simulations in 3D. In this work, two and three dimensional models of electrodes comprising o…

Ni-Fe alloy nanostructured electrodes for water splitting in alkaline electrolyser

Abstract In this work, nickel-iron alloy nanostructured electrodes obtained by template electrosynthesis method are investigated for both hydrogen and oxygen evolution reactions. Electrodes consist of nanowire arrays with high surface area that are able to ensures a high electrolytic activity. To obtain different alloy compositions, the concentration of the elements in the deposition baths is appropriately tuned. Results show that the composition of nanowires does not change linearly with the composition of deposition bath but are richer in Fe. Nanostructured electrodes are tested as both cathodes and anodes in 30 wt% KOH aqueous solution, at room temperature to determine the best alloy com…

Nanostructured Lead Electrodes with Reduced Graphene Oxide for High-Performance Lead–Acid Batteries

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 wi…

Nanostructured Nickel alloy electrodes for alkaline electrolysers

Phosphate ions detection by using an electrochemical sensor based on laser-scribed graphene oxide on paper

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 mol…

Ni/NiO thin film Sensors for Mercury ions detection by Square wave anodic stripping voltammetry

Square wave anodic stripping voltammetry (SWASV) is considered a very interesting electrochemical method for heavy metals detection in comparison to conventional techniques [1]. The main features of this technique are the high sensitivity and reproducibility (standard deviation lower than 5%), besides, the limit of detection is in the ppb level so is comparable with standard techniques such as AAS or ICP, the instrumentation is very inexpensive and easy to use and the detection time is very low. Among heavy metals, mercury is one of the most toxic for both environment and humans. In fact, it may cause serious health problems to brain, kidney and DNA. The concentration limit imposed by US En…

Electrochemical Quantification of H2O2 Released by Airway Cells Growing in Different Culture Media

Quantification of oxidative stress is a challenging task that can help in monitoring chronic inflammatory respiratory airway diseases. Different studies can be found in the literature regarding the development of electrochemical sensors for H2O2 in cell culture medium to quantify oxidative stress. However, there are very limited data regarding the impact of the cell culture medium on the electrochemical quantification of H2O2. In this work, we studied the effect of different media (RPMI, MEM, DMEM, Ham’s F12 and BEGM/DMEM) on the electrochemical quantification of H2O2. The used electrode is based on reduced graphene oxide (rGO) and gold nanoparticles (AuNPs) and was obtained by co-electrode…

Electrochemical sensor based on rGO/Au nanoparticles for monitoring H2O2 released by human macrophages

Abstract Increased oxidative burden contributes to the pathogenesis of most inflammatory diseases and is associated with aging and chronic inflammation. Macrophages contribute to the generation of reactive oxygen species (ROS) within inflamed tissues. Currently, ROS generation is measured using fluorescent probes and colorimetric/fluorimetric biochemical assays. Hydrogen peroxide (H2O2) diffuses through the cell membrane and can be monitored in the extracellular space. Herein, we present a sensor for H2O2 detection released by cells in culture supernatants. H2O2 sensing performance was evaluated using chronoamperometric detection. A sensitivity of 0.0641 μA μM−1 cm−2 with a limit of detecti…

Copper nanowire array as highly selective electrochemical sensor of nitrate ions in water

Contamination of water with nitrate ions is a significant problem that affects many areas of the world. The danger from nitrates is not so much their toxicity, rather low, as their transformation into nitrites and in particular into nitrosamines, substances considered to be a possible carcinogenic risk. 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 performed in situ. Electrochemical detection is certainly among the best techniques to obtain the above requirements. In…

Cellular and Molecular Signatures of Oxidative Stress in Bronchial Epithelial Cell Models Injured by Cigarette Smoke Extract

Exposure of the airways epithelium to environmental insults, including cigarette smoke, results in increased oxidative stress due to unbalance between oxidants and antioxidants in favor of oxidants. Oxidative stress is a feature of inflammation and promotes the progression of chronic lung diseases, including Chronic Obstructive Pulmonary Disease (COPD). Increased oxidative stress leads to exhaustion of antioxidant defenses, alterations in autophagy/mitophagy and cell survival regulatory mechanisms, thus promoting cell senescence. All these events are amplified by the increase of inflammation driven by oxidative stress. Several models of bronchial epithelial cells are used to study the molec…

Synthesis of Silver Gallium Selenide (AgGaSe2) Nanotubes and Nanowires by Template-Based Electrodeposition

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 Ga3+/Ga couple than Ag2+/Ag and Se4+/Se.…

Vertical standing copper nanowires for electrochemical sensor of nitrate in water

Nitrogen, in the forms of nitrate (NO3-), nitrite, or ammonium, is a nutrient needed for plant growth and it is a common constituent of fertilizers [1]. When fertilizers are overused, they contaminate the ground water and then the food chain. For humans, a low level of nitrate is advisable because it increases the blood flow and has a good effect on both blood pressure and cardiovascular system. On the contrary, a high concentration of nitrate can be dangerous for humans. Nitrate ions undergoes different chemical transformations (i.e. to nitrite ions by Escherichia coli) producing different nitrogen-based compound such as nitrite ions, nitric oxide and ammonia [2]. These chemicals lead to s…

Nanostructured lead-acid negative electrode with reduced graphene oxide

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,…

Electrochemical sensor for evaluating oxidative stress in airway epithelial cells

Cigarette smoke exposure induces oxidative stress within the airways. Increased oxidative burden contributes to the pathogenesis of chronic lung disorders and is associated with aging and chronic inflammation. Airway epithelial cells highly contribute to Reactive Oxygen Species (ROS) generation within injured and inflamed lung tissues. Among ROS, hydrogen peroxide (H2O2) can be monitored in the extracellular space. Herein, we present an amperometric/voltammetric sensor based on gold nanoparticles and graphene oxide able to detect H2O2 with good sensitivity and selectivity. Using this sensor, H2O2 release was measured in conditioned medium from primary bronchial epithelial cells (PBEC), bron…

Simultaneous detection of copper and mercury in water samples using in-situ pH control with electrochemical stripping techniques

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…

Reagent free electrochemical-based detection of silver ions at interdigitated microelectrodes using in-situ pH control

Abstract Herein we report on the development of an electrochemical sensor for silver ions detection in tap water using anodic sweep voltammetry with in-situ pH control; enabled by closely spaced interdigitated electrode arrays. The in-situ pH control approach allowed the pH of a test solution to be tailored to pH 3 (experimentally determined as the optimal pH) by applying 1.65 V to a protonator electrode with the subsequent production of protons, arising from water electrolysis, dropping the local pH value. Using this approach, an initial proof-of-concept study for silver detection in sodium acetate was undertaken where 1.25 V was applied during deposition (to compensate for oxygen producti…

Silver based sensors from CD for chloride ions detection

This preliminary work shows a new and innovative way to produce silver based electrodes from compact discs and its application towards the detection of chloride ions. A complete sensor was obtained from the compact discs with working, reference and counter electrode made of silver. Chloride ions were detected by exploiting the high affinity of silver with this anion to produce silver chloride. This electrochemical oxidation of silver can be monitored by using an electrochemical technique such as linear scan voltammetry. Indeed, during linear scan voltammetry the oxidation of silver to silver chloride lead to a peak current that increases linearly with chloride concentration. Using this tech…

Metodo per la realizzazione di sensori elettrochimici con materiali recuperati da dispositivi di memorizzazione di scarto e sensore elettrochimico ottenibile con tale metodo

Metodo per la realizzazione di sensori elettrochimici con materiali recuperati da dispositivi di memorizzazione di scarto, quali CD e DVD

Copper and Palladium NWs for Hydrogen Peroxide detection

H2O2 is a wide used chemical in different field, like in paper and textile industries and pharmaceutical applications. Furthermore, H2O2 concentration in human body is related to glucose concentration because the reaction between glucose and glucosidase produce hydrogen peroxide [1] . Moreover, is used as a biomarker of oxidative stress, being an oxidative specie [2] . For all these reasons, researcher all over the world are working to develop new and novel strategies for in situ, non-invasive and fast detection of this chemical. One of these fields concern the electrochemical sensors, that are sensors with an electrical (current, potential, impedance) output. The surface area the electrode…

Optimization of Electrodeposited Nickel-Zinc Alloys for Alkaline Electrolyzer with Nanostructured Electrodes

It is common opinion that hydrogen will become increasingly important over time. However, many research efforts still need to be made to develop efficient, low-cost and carbon-free hydrogen production. In this context, electrolysers will play a key role, but it is necessary to develop efficient and low-cost electrode/electrocatalyst materials. In this work, Nickel-Zinc alloy electrodes with nanowires morphology were investigated as cathode for alkaline electrolyzer. Electrodes were obtained by the simple method of template electrosynthesis that is also inexpensive and scalable. Nanostructured electrodes were analysed by morphological and chemical analyses. The nanowires composition is depen…

Fabrication of CZTSe/CIGS Nanowire Arrays by One-Step Electrodeposition for Solar-Cell Application

The paper reports some preliminary results concerning the manufacturing process of CuZnSnSe (CZTSe) and CuInGaSe (CIGS) nanowire arrays obtained by one-step electrodeposition for p-n junction fabrication. CZTSe nanowires were obtained through electrodeposition in a polycarbonate membrane by applying a rectangular pulsed current, while their morphology was optimized by appropriately setting the potential and the electrolyte composition. The electrochemical parameters, including pH and composition of the solution, were optimized to obtain a mechanically stable array of nanowires. The samples were characterized by scanning electron microscopy, Raman spectroscopy, and energy-dispersion spectros…

Pd-NWs ordered arrays for electrochemical sensing of H2O2

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 …

Galvanic Deposition of Calcium Phosphate/Bioglass Composite Coating on AISI 316L

Calcium phosphate/Bioglass composite coatings on AISI 316L were investigated with regard to their potential role as a beneficial coating for orthopedic implants. These coatings were realized by the galvanic co-deposition of calcium phosphate compounds and Bioglass particles. A different amount of Bioglass 45S5 was used to study its effect on the performance of the composite coatings. The morphology and chemical composition of the coatings were investigated before and after their aging in simulated body fluid. The coatings uniformly covered the AISI 316L substrate and consisted of a brushite and hydroxyapatite mixture. Both phases were detected using X-ray diffraction and Raman spectroscopy.…

A nanostructured sensor of hydrogen peroxide

Abstract 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 comp…

DOPAMINE ELECTROCHEMICAL SENSOR BASED ON REDUCED GRAPHENE OXIDE AND METAL NANOPARTICLES

Dopamine (DA) is one of the most important neurotransmitters released from the brain, and is involved in many different biological processes. This neurotransmitter influences the processes that involve memory, sleep, mood, learning, and so on. Besides, in the last years, dopamine concentration in human body fluids has been related to some neurodegenerative pathologies, such as Parkinson and Alzheimer’s diseases [1]. It is well known that these pathologies are due to the formation of amyloids plaques that block part of the brain. Many literature data reports that DAergic neurons (areas of midbrain where DA is synthesized) shows a different activity when amyloid plaques are present with a con…

Green and Integrated Wearable Electrochemical Sensor for Chloride Detection in Sweat

Wearable sensors for sweat biomarkers can provide facile analyte capability and monitoring for several diseases. In this work, a green wearable sensor for sweat absorption and chloride sensing is presented. In order to produce a sustainable device, polylactic acid (PLA) was used for both the substrate and the sweat absorption pad fabrication. The sensor material for chloride detection consisted of silver-based reference, working, and counter electrodes obtained from upcycled compact discs. The PLA substrates were prepared by thermal bonding of PLA sheets obtained via a flat die extruder, prototyped in single functional layers via CO2 laser cutting, and bonded via hot-press. The effect of co…

Anodic Alumina Membranes: From Electrochemical Growth to Use as Template for Fabrication of Nanostructured Electrodes

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 …

Wearable sensor for real-time monitoring of oxidative stress

Wearable sensor for real-time monitoring of hydrogen peroxide in simulated breath

Electrochemical detection of uric acid and ascorbic acid using r-GO/NPs based sensors

Abstract A sensitive and selective electrochemical sensor, based on reduced graphene oxide and gold nanoparticles obtained by simple co-electrodeposition, was developed for the detection of uric acid and ascorbic acid. Because of the electrochemical oxidation of both uric and ascorbic acid depending on the pH, the sensor performances were studied at different pH values. Excellent results were obtained for uric acid detection in a linear range from 10 to 500 µmol dm−3 with a sensitivity of 0.31 µA cm−2 µM−1. A limit of detection and quantification of 3.6 µM and 10.95 µmol dm−3, respectively, was calculated. Sensors showed good selectivity toward different interfering species present in the m…

Electrochemical Synthesis of Zinc Oxide Nanostructures on Flexible Substrate and Application as an Electrochemical Immunoglobulin-G Immunosensor

Immunoglobulin G (IgG), a type of antibody, represents approximately 75% of serum antibodies in humans, and is the most common type of antibody found in blood circulation. Consequently, the development of simple, fast and reliable systems for IgG detection, which can be achieved using electrochemical sandwich-type immunosensors, is of considerable interest. In this study we have developed an immunosensor for human (H)-IgG using an inexpensive and very simple fabrication method based on ZnO nanorods (NRs) obtained through the electrodeposition of ZnO. The ZnO NRs were treated by electrodepositing a layer of reduced graphene oxide (rGO) to ensure an easy immobilization of the antibodies. On I…

Electrochemical detection of dopamine with negligible interference from ascorbic and uric acid by means of reduced graphene oxide and metals-NPs based electrodes.

Abstract Dopamine is an important neurotransmitter involved in many human biological processes as well as in different neurodegenerative diseases. Monitoring the concentration of dopamine in biological fluids, i.e., blood and urine is an effective way of accelerating the early diagnosis of these types of diseases. Electrochemical sensors are an ideal choice for real-time screening of dopamine as they can achieve fast, portable inexpensive and accurate measurements. In this work, we present electrochemical dopamine sensors based on reduced graphene oxide coupled with Au or Pt nanoparticles. Sensors were developed by co-electrodeposition onto a flexible substrate, and a systematic investigati…

Nanostructured Electrochemical Devices for Sensing, Energy Conversion and Storage

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 polyca…

Nanowire Ordered Arrays for Electrochemical Sensing of H2O2

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 importan…

Electrochemical detection of chloride ions using Ag-based electrodes obtained from compact disc

Abstract In this work electrochemical sensors fabricated from compact disc material (waste or new) are used to quantify chloride ions in different types of samples. All three electrodes, working, counter, and pseudo-reference electrodes, were fabricated from the compact disc and directly used. Different parameters were studied in order to demonstrate the possibility of using this waste material for efficient and low-cost electrochemical sensors. Chloride sensing performance was evaluated using linear scan voltammetry as the detection technique. A sensitivity of 0.174 mA mM−1 cm−2 with a limit of detection of 20 μM and excellent selectivity against many interferents was observed. Selectivity…

A Theoretical and Experimental Study of Electrochemical pH Control at Gold Interdigitated Microband Arrays

In electroanalysis, solution pH is a critical parameter that often needs to be adjusted and controlled for the detection of particular analytes. This is most commonly performed by the addition of chemicals, such as strong acids or bases. Electrochemical in-situ pH control offers the possibility for the local adjustment of pH at the point of detection, without additional reagents. FEA simulations have been performed to guide experimental design for both electroanalysis and in-situ control of solution pH. No previous model exists that describes the generation of protons at an interdigitated electrode array in buffered solution with one comb acting as a protonator, and the other as the sensor.…