Uniform Large-Area Free-Standing Silver Nanowire Arrays on Transparent Conducting Substrates

Arrays of silver nanowires have received increasing attention in a variety of applications such as surface-enhanced Raman scattering (SERS), plasmonic biosensing and electrode for photoelectric devices. However, until now, large scale fabrication of device-suitable silver nanowire arrays on supporting substrates has seen very limited success. Here we show the synthesis of free-standing silver nanowire arrays on indium-tin oxide (ITO) coated glass by pulsed electrodeposition into anodic aluminum oxide (AAO) templates. We use an in situ oxygen plasma cleaning process and a sputtered Ti layer to enhance the adhesion between the template and ITO glass. An ultrathin gold layer (2 nm) is deposited as a nucleation layer for the electrodeposition of silver. An unprecedented high level of uniformity and control of the nanowire diameter, spacing and length has been achieved. The absorption measurements show that the free-standing silver nanowire arrays possess tunable plasmonic resonances.publishe

Effects of Carrier, Leveller, and Booster Concentrations on Zinc Plating from Alkaline Zincate Baths

Organic additives are required for alkaline zincate plating baths to obtain an acceptable coating on steel for corrosion protection. The effects and possible interactions of three commercial additives (Eldiem Carrier, Eldiem Booster, and Bright Enhancer 2x on zinc electrodeposition from a high-concentration alkaline zincate bath were investigated. Visually acceptable deposits were produced within the current density range of 130 to 430 A m−2 for most additive conditions examined. Over concentration ranges examined, decreasing the booster concentration led to brighter zinc deposits, and an interaction between the carrier and the booster was detected. The additives fostered the formation of compact and adherent coatings as illustrated by scanning electron microscopy. Throwing power and current efficiency were not impacted by the additives over the concentration ranges examined. Linear sweep voltammetry proved that the additives increased the overpotential for zinc deposition. The additive combination that produced the brightest deposit also demonstrated the strongest adsorption of additives in linear sweep voltammetry

Self-lubricating Cu-MWCNT coatings deposited from an ecofriendly glutamate-based electrolyte

Self-lubricating coatings have been studied for a long time due to their convenience compared to systems which need periodic lubrication. For this reason, Cu-CNT composite coatings with high wear resistance and low coefficient of friction were obtained by electrodeposition from an ecofriendly alkaline glutamate-based electrolyte. Deposition experiments were performed at various experimental conditions in the presence of low-frequency ultrasound agitation to ensure particle dispersion and enhance their incorporation in the Cu matrix. Moreover, the effect of 2-Butyne-1,4-diol (an additive use in glutamate-based formulations) on coatings mechanical and tribological properties was assessed. Both pure Cu and Cu-CNT were obtained under all the experimental conditions considered and later characterized by SEM and XRD. Finally, pin-on disk tests were performed to estimate the coefficient of friction and determine the wear resistance. The results showed that incorporation of CNT to the copper matrix led to an improvement of the tribological performance of pure Cu, regardless of deposition parameters. Furthermore, it was found that 2-Butyne-1,4-diol had a strong influence on deposit microhardness and tribological performance, as a result of the changes in microstructure induced by this additive which promoted the development of a (111) texture. Likewise, the incorporation of particles to the Cu matrix promoted changes in surface morphology as well as in the preferred crystalline orientation, promoting crystal growth along the [311] direction. The results indicate that this simple and cheap methodology is suitable for fabrication of self-lubricating coatings.Fil: Bengoa, Leandro Nicolás. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Tecnología de Pinturas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones en Tecnología de Pinturas; ArgentinaFil: Seré, Pablo Ricardo. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Tecnología de Pinturas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones en Tecnología de Pinturas; ArgentinaFil: Pary, Paola. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Tecnología de Pinturas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones en Tecnología de Pinturas; ArgentinaFil: Conconi, María Susana. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; ArgentinaFil: Folgueiras, José María. Universidad Tecnológica Nacional. Facultad Regional Delta; ArgentinaFil: Morel, Eneas Nicolas. Universidad Tecnológica Nacional. Facultad Regional Delta; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Torga, Jorge Román. Universidad Tecnológica Nacional. Facultad Regional Delta; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Egli, Walter Alfredo. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Tecnología de Pinturas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones en Tecnología de Pinturas; Argentin

Electrochemical Characterization of a Cu(II)-Glutamate Alkaline Solution for Copper Electrodeposition

In this study, a cyanide-free electrolyte containing glutamate as a complexing agent is investigated as a more environmentally friendly alternative for alkaline copper plating. The solution was prepared using copper sulfate, sodium glutamate and potassium hydroxide. The pH of the electrolyte (pH = 8) and the ratio ligand:copper (R = 3), were chosen from equilibrium diagrams in order to avoid the formation of insoluble complexes and oxides. The electrochemical response of the system was determined by means of cyclic voltammetry. The results showed that copper electroreduction occurs in a two steps pathway with a cuprous-glutamate complex as an intermediate. Galvanostatic deposits obtained from the bath under study had proper brightness and roughness at the selected current density conditions. Scanning electron microscopy and X-Ray diffraction were carried out in order to characterize deposits surface morphology and crystal orientation. Chronoamperometric experiments together with atomic force microscopy proved that copper deposits grow through an instantaneous nucleation mechanism in which nuclei are not exactly spherical. These preliminary studies suggest that the Cu+2-glutamate electrolyte may be suitable for the replacement of cyanide baths in copper lectrodeposition at high pH without the need of additives as this electrolyte acts as a self-levelling system. Also, the use of this electrolyte could eliminate the need of performing strike deposits on less noble substrates, allowing a one step plating process.Centro de Investigación y Desarrollo en Tecnología de Pintura

Effect of the citrate ion on the electrochemical behavior of tin and steel

RESUMEN: El presente trabajo pretende hacer un aporte al conocimiento del comportamiento electroquímico de recipientes de hojalata en medio del ion citrato, y al papel que juega la concentración de dicho ion en la estabilidad de los recipientes.Todo ello, a través del estudio electroquímico individual de los materiales con los cuales son fabricados los recipientes de hojalata, acero y estaño. El estudio se llevó acabo mediante medidas de polarización potenciodinámica e impedancia electroquímica sobre electrodos fabricados con ambos materiales e inmersos en soluciones de diferentes concentraciones de citrato a un valor de pH de 3,0. Se evidencia que a este valor de pH, el ion citrato ejerce un notable efecto de despolarización anódica sobre el estaño, por la formación de complejos solubles y estables. Esto hace que el estaño se torne anódico respecto al acero pudiendo otorgar una protección anticorrosiva al sustrato de acero de los recipientes de hojalata.ABSTRACT: The present work tries to do a contribution to the knowledge of the electrochemical behavior of tinplate containers in citrate ion medium and the role that citrate ion concentration plays on the stability of the containers; all that, through the individual electrochemical study of the materials of which the tinplate is made, steel and tin. The study was done by potentiodynamic polarization and electrochemical impedance on electrodes made with both materials, immersed in solutions of different citrate concentrations at pH 3,0. It was evidenced that the citrate ion has a remarkable effect of anodic depolariza tion on tin with the formation of soluble and stable complexes. This causes that tin becomes anodic with respect to the steel being able to grant an anticorrosive protection to the steel substrate of the tinplate containers

Influence of organic additives on the behaviour of zinc electroplating from alkaline cyanidefree electrolyte

Two similar polymeric organic compounds from the polyquaternium family were studied as levelling additives in an alkaline cyanide-free zinc plating electrolyte. One additive (LA) has amide bonds between its monomers and the other (LU) has urea unions in its chemical structure. Copper cementation on zinc and gas evolution during aging of the zinc coatings were used to evaluate the effect of the chemical structure of the organic additives on the characteristic deleterious aging process of the coatings when electrodeposited with LA. Scanning electron microscopy and X-ray diffraction were used to follow surface morphology and crystallographic modifications of the coatings during aging. Faster copper cementation kinetics, zinc whiskers growth, blistering of the coating and N₂, CH₄, CO₂ and H₂ evolution were observed during accelerated aging of the coatings when LA was used. The coatings produced with LU did not show any aging effect. These studies show the strong influence that subtle changes in the chemical structure of the organic additive may have on the performance of zinc coating during storage.Centro de Investigación y Desarrollo en Tecnología de PinturasCentro de Investigación y Desarrollo en Ciencias AplicadasCentro de Tecnología de Recursos Minerales y Cerámic

Bronze electrodeposition from an acidic non-cyanide high efficiency electrolyte: tribological behavior

Bronze coatings were electrodeposited onto a rotating cylinder electrode from a novel non-cyanide acid plating bath with high efficiency (92%). Deposits were obtained from a phenol sulfonic acid bath and their morphology, phase composition and tribological behavior were characterized. Cyclic and linear sweep voltammetries were used to study the effect of organic additives on the reduction processes to achieve an adequate formulation. The resulting bronze deposit consisted of a mono α-phase matrix with a 78% Cu and 22% Sn composition. Dry sliding wear tests were carried out employing a homemade ball on ring system and the coefficient of friction and wear resistance were quantified at different normal loads. Surface characterization of the bronze coatings showed that the resulting roughness is detrimental for the wear resistance of the deposit. This is evidenced by a higher friction coefficient and wear volume of Cu/Sn compared to a conventionally electrodeposited copper coating.Centro de Investigación y Desarrollo en Tecnología de Pintura

Zinc plating from alkaline non-cyanide bath

“Alkaline non-cyanide zinc plating baths are preferred when trying to avoid the toxicity of cyanide baths or corrosivity of acid baths. Without additives, alkaline zincate baths produce powdery non-adherent deposits which have no use in commercial plating. Additives must be added at optimum concentrations to produce adherent, bright and uniform zinc deposits. In this study electrochemical tests were used to determine effects of additives on cathodic polarization, throwing power and morphology of deposits. Current density distribution in a unique bath of 37.5 g L-1 Zn and 210 g L-1 NaOH was modelled using COMSOL and validated two plating cells with different geometries”--Abstract, page iv

A Novel Two-Step Electrochemical Deposition Method for Sn-Pd Electrocatalyst Synthesis for a Potential Application in Direct Ethanol Fuel Cells

Sn-Pd electrocatalysts with a constant atomic ratio of 60 at.% Sn‒40 at.% Pd suitable for potential application in direct ethanol fuel cells were synthesized using a novel two-step electrodeposition method. First, Sn was electrodeposited in various forms of dendrites, from spear-like and needle-like to individual fern-like dendrites to a network of intertwined fern-like dendrites, by varying the cathodic potential and then performing electrodeposition of Pd at a constant current density in the second step. A morphological and elemental analysis of Sn and Sn-Pd electrocatalysts was performed using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) techniques, while the size of Sn dendrites was analyzed using the particle size distribution (PSD) method. Cyclic voltammetry (CV) and chronoamperometry were applied in order to study the catalytic behavior of Sn-Pd electrocatalysts in the ethanol oxidation reaction (EOR), while CO stripping was used to estimate the antipoisoning capability of the electrocatalysts. The Sn surface morphology of the sub-layer was highly correlated with the electrocatalytic activity of the examined Sn-Pd electrocatalysts. The high activity it presented towards the EOR showed the suitability of the Sn-Pd electrocatalyst constructed from individual fern-like Sn dendrites as a sub-layer. Compared to Pd alone, this Sn-Pd catalyst showed more than 3 times higher activity and improved EOR kinetics. This enhancement in the catalytic activity of the Sn-Pd electrocatalysts is attributed to both the morphological characteristics of Sn as a sub-layer and the bifunctional effect

3D Printing Technologies

The family of technologies collectively known as additive manufacturing (AM) technologies, and often called 3D-printing technologies, is rapidly revolutionizing industrial production. AM’s potential to produce intricate and customized parts starting from a digital 3D model makes it one of the main pillars for the forthcoming Industry 4.0. Thanks to its advantages over traditional manufacturing methodologies, AM finds potential applicability in virtually all production fields. As a natural consequence of this, research in this field is primarily focused on the development of novel materials and techniques for 3D printing. This Special Issue of Technologies, titled “3D Printing Technologies”, aims at promoting the latest knowledge in materials, processes, and applications for AM. It is composed of six contributions, authored by influential scientists in the field of advanced 3D printing. The intended audience includes professors, graduate students, researchers, engineers and specialists working in the field of AM