Galvanic Technique Research Articles

Spontaneous aggregation-enhanced electrochemiluminescence via galvanic strategy

Researchers unremittingly strive to develop innovative luminophores to enhance intrinsic electrochemiluminescence (ECL) performance. However, the potential to harness facile strategies, such as manipulating the physical properties of luminophores while retaining functional chemical properties to fabricate cost-effective ECL complexes, remains underexplored. Herein, we reported a novel and efficient one-step galvanic technique to actualize aggregation-enhanced ECL (AEECL) of ruthenium complexes. It marked the first instance of the galvanic process being employed to synthesize aggregate luminophores through electrostatic attraction. The ECL intensity and efficiency of the prepared ruthenium complexes with AEECL properties surpassed traditional ruthenium complexes by 8.9 and 13.6 times, respectively, outperforming most reported luminophores. Remarkably, the target luminophore exhibited high stability across varied scan rates and temperatures. Furthermore, a binder-free and carbon paper-based AEECL analytical device for lidocaine detection was fabricated, achieving a satisfactory detection limit (0.34 nM) and selectivity. The convenient modulation strategy of aggregate structure, along with the transformative leap from insufficient ECL to AEECL, bring forth a new revenue in aggregate science. This research also promises a universally applicable and versatile protocol for future biological analysis and bioimaging applications.

Strategically Designed Pd-Induced Changes in Alkaline Hydrogen Evolution Reaction and Oxygen Evolution Reaction Performances of Electrochemical Water Oxidation by the Galvanically Synthesized MoO2/MoO3 Composite Thin Film.

Electrochemical water oxidation is believed to be an effective pathway to produce clean, carbon-free, and environmentally sustainable green energy. In this work, we report a simple, easy-to-construct, facile, low-cost, and single-step galvanic technique to synthesize a Pd-supported temperature-assisted MoOx thin film nanocomposite for effective water oxidation. The most suitable nanocomposite exhibits very low overpotential at 10 mA/cm2 with smaller Tafel slope values for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) processes in an alkaline medium. The formation of a metal oxide-metal junction accelerates the growth of more active sites, promoting induced electronic synergism at the MoOx-Pd interface. This endows higher electrical conductivity and faster electron transfer kinetics, thus accelerating the faster water dissociation reaction following the Tafel-Volmer mechanism to boost the HER process in an alkaline medium. The excellent electrochemical HER and OER performances of our electrocatalyst even supersede the accomplishments of the benchmark catalysts Pt/C and RuO2. Moreover, neither of these two catalysts demonstrates both catalytic reactions, i.e., HER and OER at the same time, which have been observed for our synthesized catalyst. Our findings illustrate the potential of a thin-film MoOx-Pd nanocomposite to be an exceedingly effective electrocatalyst developed by interface engineering strategies. This also provides insight into designing several other semiconductor composite catalysts using simple synthesis techniques for highly efficient HER/OER processes that could be alternatives to benchmark electrocatalysts for water electrolysis.

Orthodontic and prosthodontic reatment of subgingival fractures of single-root teeth – a case study

<b>Introduction.</b> Combined orthodontic and prosthodontic treatment usually consists of three stages: pre-orthodontic, orthodontic and prosthodontic treatment. This study discusses the orthodontic and prosthodontic treatment stages of subgingival fractures of single-root teeth. The treatment is presented on the basis of the case involving the subgingival fracture of the upper right canine tooth in a 25-years old patient. <b>Aim.</b> The aim of this study is to present the results of the treatment involving the improvement in the function and aesthetics of the upper jaw, following the fracture. We focused specifically on the creation of proper conditions to implement an interdisciplinary treatment. The priority of such treatment is to uncover the contour of the fractured root. The success of the treatment depends on the degree of fracture confirmed by X-ray examinations, the length of the undamaged part of the root remaining in the bone and its anatomical structure. These factors influence the result of the endodontic treatment and the following prosthodontic restoration. <b>Materials and methods.</b> It is possible to uncover the contour of the fractured root by means, among others, of the application of a special orthodontic technique called extrusion. In the case of the treated patient, extrusion was performed by a fixed orthodontic device placed on the neighbouring teeth and a hook cemented in the canal of the fractured tooth. The extrusion was additionally supported by cutting periodontal fibres gradually. The orthodontic treatment involved 6 appointments and lasted 6 weeks from the placement of the fixed orthodontic device till the stage when the entire contour of the root’s bearing surface was revealed. Correct orthodontic therapy was necessary for a subsequent, successful, prosthodontic reconstruction. The prosthodontic treatment lasted 1 week and involved 2 appointments. It was performed in two stages: first, crown and root inlay was made of gold alloy (87%) and then, an aesthetic crown made of gold and porcelain (galvanic technique). <b>Results and discussion.</b> As a result of the combined treatment, it was possible to uncover the fractured root 2 mm above the bone plate of the alveolar process, and, consequently, to recreate the damaged tooth by means of a prosthodontic reconstruction. <b>Conclusions.</b> Combined orthodontic and prosthodontic treatment determines a successful prosthodontic reconstruction, thus restoring the function and aesthetic effect of the upper jaw and the whole oral cavity in a relatively short period of time.

A pre-Columbian galvanic technique able to explain the gilding of copper in northern Peru

Around 150 BCE and 700 CE, pre-Columbian goldsmiths in the Peruvian northern coastline developed a method for gilding copper. The characteristics of the resulting pieces are substantially different from those obtained by hammering, embossing, and casting. We discuss two electrochemical gilding methods that were possibly developed by pre-Columbian goldsmiths. The first method consists of electrochemical replacement where copper is immersed in a solution containing dissolved gold. The second method utilizes the same solution but includes pyrite to form a galvanic cell with copper as the cathode and pyrite as the anode. Characterizations via X-ray fluorescence (XRF) and Scanning electron microscopy with energy dispersion spectroscopy (SEM-EDX) allowed a comparison of the results of the two methods with archaeological samples. The electrochemical replacement method does not reach thicknesses observed in archeological samples and delivers irregular gilding due to the formation of anodic spots on copper. Meanwhile, including pyrite as an anode in the electrochemical cell leads to a more homogeneous deposition of gold with layer thicknesses similar to those found in archaeological samples. This work contributes to understanding pre-Columbian techniques lost before the Inca Empire.

Hydroxyl radical assisted enzyme-free electrochemical detection and oxidation of cholesterol by a galvanically deposited layer-by-layer ZnO/WO3 thin film nanocomposite

A facile low-cost two-step galvanic technique is employed to deposit a lbl ZnO/WO3 thin film nanocomposite on FTO substrate for an efficient electrochemical oxidation of cholesterol to oxysterol and thereby sense it through ˙OH radical formation.

Platinum Nanoparticles Modified Copper/Titanium Electrodes as Electrocatalysts for Borohydride Oxidation.

In this study, sodium borohydride oxidation has been investigated on the platinum nanoparticles modified copper/titanium catalysts (PtNPsCu/Ti), which were fabricated by employing the electroless copper plating and galvanic displacement technique. ICP-OES, XRD, FESEM, and EDX have been used to characterize PtNPsCu/Ti catalysts’ composition, structure, and surface morphology. The oxidation of sodium borohydride was examined on the PtNPsCu/Ti catalysts using cyclic voltammetry and chrono-techniques.

Ensembles of Layered Nanowires, Obtained by Matrix Synthesis Technique, for Generation of THz Irradiation

Ensembles of parallel nanowires, consists of the parts from different ferro-magnetic metals (for example-FeNi/Co/FeNi) were obtained by method of template synthesis. It was shown that such samples could be the sources of electromagnetic emission – irradiation of Terahertz range. It could be detected when current passed through the contacts at the sample with these wires. The methods of obtaining nanowires was proposed (two-bath galvanic technique), formation of contact layers at the surface (parallel narrow strips of metal) were proposed. The features of these radiation were investigated–it‘s threshold character, it‘s non-thermal origin and spatial distribution. The calculation was also presented, which demonstrated possibility of detecting of Terahertz irradiation, using ensemble of such nanowires, included ferro-magnetic metal and anti-ferromagnetic metal.

Water Resources Management and Wastewater Treatment in the Democratic Republic of Congo (D.R.C): Application of Galvanic Treatment, Results and Prospectives

The rapid industrial development and population growth increase the utilization of fresh water resulting in an increase of the amount of wastewater. Several Countries face a double challenge with regard to water resources, namely meeting the growing need for water for the population and treating the wastewater generated for application. The toxicity found in these water streams threatens the environment and human health. Hence the urgent need is to treat wastewater. The DRC is not immune from this threat. Its average population growth rate has exceeded the 3% and the number of industries it hosts continues to increase. The wastewater generated by this increasing pressure from urbanization and industrialization must be treated as required in the Congolese legal arsenal. Various factors need to be considered prior choosing the water treatment method. The choice must take into account the imperatives of the moment which are: modernization (local context) and sustainable development (international context). There are several wastewater treatments that are widely used for the removal of toxic elements such as ion exchange, reverse osmosis, chemical precipitation and electro-coagulation just to name a few. The most recent studies have shown that the galvanic technique can be used in the purification of water from domestic and industrial origin to meet drinking water standards. Various researchers have used this technique at laboratory and pilot scale demonstrating its cost-effectiveness as it uses no chemical reagents, consumes less energy and occupies only a small space for processing large flows. However, there are very few studies demonstrating the success of this treatment on an industrial scale. Therefore, this work seeks to understand and master the mechanisms that take place in the galvanic treatment. In addition, this study focuses on the development of a robust prototype that is adaptable to the needs of various users while at the same time being relatively cheap to meet the national needs.

Growth mechanism and repassivation kinetic determinations on stainless steel under sliding: Role of the solution pH and dissolved oxygen concentration

The tribo electrochemical behavior of 2205 duplex stainless steel had been studied under acidic and neutral solutions with control of the dissolved dioxygen. The study focused on the oxide film formation using a galvanic technique approach implemented in a tribometer. Higher wear rates were measured in low pH and aerated solution. In low O2 concentration, a wear reduction was observed for each pH. Analysis of the passivation transients showed the pH influence on the oxide growth mechanism, irrespective of the O2 level. Temporal analysis of the transients confirmed the faster passivation of the wear track in acidic solution. In a controlled O2 environment, the nucleation and the oxide growth were slow down, irrespective of pH. The degradation rate was then correlated to the passivation kinetic and the aging of the passive film.

WASTEWATER TREATMENT OF INDUSTRIAL ENTERPRISES BY THE NATURAL METALS

Purpose. The paper deals with the galvanic coupling effect (time of treatment and other factors) on the removal of oil, synthetic surface active substances (SSAS), chromium, etc. from waste process solutions used in metalworking. It presents an overview of wastewater treatment technologies from heavy metal ions based on physicochemical processes. Methodology. To restore hexavalent chlorine to trivalent, authors decided to use the existing averager of acid-alkaline effluents as a kind of galvanic coagulant, for which it was filled with iron turnings and crushed coke. Findings. Authors researched wastewater of the electrotechnical industry and highlighted sorption methods for their purification with the use of coagulants, ion exchange. They considered a new galvanocoagulation method for purification from heavy metal (HM) ions (arsenic, chromium, non-ferrous metals), as well as petroleum products and organic substances dissolved in water. Permissible values of the quality indicators of wastewater and water in reservoirs are given. The classification of heavy metal groups according to the degree of toxic effect is presented. Their influence on the human body is considered. The use of the «LOTOS» reactor in the technological process of electroplatings wastes cleaning allows: to process them in a single stream, to abandon special reagents for cleaning effluents from hexavalent chromium and cyanides, to exclude the need for acidification of effluents, to reduce the use of alkaline reagents up to complete rejection of them, to reduce the equipment rate and number of production personnel (their main function is to purify solutions containing up to 1 g/dm3 of hexavalent chromium. The reactor consists of unified modules, mounted in a single frame. Originality. On the basis of experimental research work, it was established possibility in principle of treatment of all liquids under research by the galvanocoagulation method. The method consists in contacting of wastewater simultaneously with copper and steel shavings (scrap) without using an external source of electric current. Practical value. The article highlights the topical issues of wastewater treatment from salts of heavy metals, which is necessary for sanitary and ecological purposes. We propose modern energy-saving and low-energy-consuming simple methods, such as the galvanic technique. The modern plant is widely used in industry, electroplating and metalware production. The described methods have a number of positive properties in the economic and energy relations. Salts of heavy metals are dangerous pollutants for both sewage and drinking water. Therefore, water treatment is a very important problem in the field of the environment of our country and abroad. The cleaning effect is achieved within 95 ... 98%.

Fabrication of stable, efficient and recyclable p-CuO/n-ZnO thin film heterojunction for visible light driven photocatalytic degradation of organic dyes

We report the photocatalytic activity of p-CuO/n-ZnO thin film heterojunction fabricated by modifying our previously reported simple galvanic technique. The fabricated heterojunction exhibits excellent photocatalytic activity and re-usability towards degradation of three different dyes under visible light source. Various samples have been prepared with different compositions to interpret the degradation mechanism.

A simple electrochemical route to deposit Cu7S4 thin films and their photocatalytic properties

Photo catalytically active Cu7S4 thin films on Fluorine doped Tin Oxide (FTO) coated glass substrates were successfully prepared using a simple, low-cost electrochemical technique (Galvanic technique), providing an economic way of obtaining nanostructured Cu7S4 thin films. The deposited films were characterized by its optical, structural and morphological properties. XRD pattern of the as-deposited Cu7S4 thin film shows monoclinic phase. UV–vis spectral analysis of the film gives direct band-gap of 1.95eV. The FESEM images show uniform distribution of spherical crystallites with compactly packed needle shaped nano-grains. The additional roughness was achieved in the nano-grain like morphology. The needle shaped nano-grains interact efficiently with the dye molecules and results in a strong photo catalytic degradation of Rose-Bengal (RB) dye. Effect of thickness on the photocatalytic degradation performance was studied and linear increase in rate constant values with thicknesses was obtained.

A novel approach for MEMS with galvanic protection on SOI wafer

A novel SOI-MEMS process with galvanic protection technique is presented in this paper. After front-end-of-line processes and metallization with Au on SOI wafers, the moving structures and release trenches are patterned by using a single mask. A combination of RIE and DRIE was employed to define the moving structures and release trenches. In the releasing process, the silicon substrate was etched normally while the exposed silicon on SOI layer was passivated by the galvanic cell that consisted of top silicon layer and Au electrode in TMAH solution. Compared with other methods, this is a simplified process. As no protection layer on the sidewalls was required for TMAH etching, all of the lithography was performed on the plain surface instead of the high topography surface. Aside from this, the released cavity has a large space that provides less air damping. The undercut of the anchor is controlled by anisotropic etching which results in desirable anchors. A double-ended tuning fork resonator was fabricated to verify the processes. The resonant frequency of the resonator was measured as 3.098 MHz with a quality factor of 730 in an atmospheric environment.

Photocatalytic activity of galvanically synthesized nanostructure SnO2 thin films

The study demonstrates an approach to synthesize nanostructure SnO2 thin films on TCO (transparent conducting oxide) coated glass substrates by galvanic technique. Aqueous solution of hydrated stannic chloride (SnCl4⋅5H2O) in potassium nitrate (KNO3) solution was used as the working solution. The process involves no sophisticated reactor or toxic chemicals, and proceeds continuously under ambient condition; it provides an economic way of synthesizing nanostructure SnO2 semiconductor thin films. The influence of sintering temperature on crystalline structure, morphology, electrical and dielectric properties has been studied. A detail analysis of I−V, C−V and dielectrics for annealed SnO2 thin films have been carried out. The morphological advantage i.e. nanoporous flake like structure allows more efficient transport of reactant molecules to the active interfaces and results a strong photocatalytic activity for degrading methyl orange (MO) dye.

Palladium–Silver-Activated ZnO Surface: Highly Selective Methane Sensor at Reasonably Low Operating Temperature

Metal oxide semiconductors (MOS) are well known as reducing gas sensors. However, their selectivity and operating temperature have major limitations. Most of them show cross sensitivity and the operating temperatures are also relatively higher than the value reported here. To resolve these problems, here, we report the use of palladium-silver (70-30%) activated ZnO thin films as a highly selective methane sensor at low operating temperature (∼100 °C). Porous ZnO thin films were deposited on fluorine-doped tin oxide (FTO)-coated glass substrates by galvanic technique. X-ray diffraction showed polycrystalline nature of the films, whereas the morphological analyses (field emission scanning electron microscopy) showed flake like growth of the grains mainly on xy plane with high surface roughness (107 nm). Pd-Ag (70-30%) alloy was deposited on such ZnO films by e-beam evaporation technique with three different patterns, namely, random dots, ultrathin (∼1 nm) layer and thin (∼5 nm) layer as the activation layer. ZnO films with Pd-Ag dotted pattern were found show high selectivity towards methane (with respect to H2S and CO) and sensitivity (∼80%) at a comparatively low operating temperature of about 100°C. This type of sensor was found to have higher methane selectivity in comparison to other commercially available reducing gas sensor.

Galvanic gold plating for fixed dental prosthesis

Metal ceramic partial fixed dental prostheses have been commonly used for the replacement of missing teeth for many years. Because of an increase in the price of gold, base metal alloys have been the choice of alloy for the fabrication of metal ceramic restorations in many dental clinics. Some major disadvantages of base metals are their corrosion and the dark coloration they may cause at the crown margins. This article describes a galvanic gold-plating technique, which is used to minimize corrosion and improve the esthetics of metal ceramic restorations fabricated with Cr-Co base metal alloys. This technique involves the deposition of a 6 μm to 8 μm 24 K gold layer directly onto the Cr-Co cast prosthesis framework. The technique improves metal surface properties, making them more biocompatible and usable, however, requires additional equipment and experienced laboratory technicians. Clinical studies should be performed to corroborate the long term success of this technique.

Assessment of Preferential Weld Corrosion of Carbon Steel Pipework in CO2-Saturated Flow-Induced Corrosion Environments

Preferential weld corrosion (PWC) has posed a problem to the oil and gas industry for a number of years. The general consensus from authors is that environmental effects take precedence over the weld chemical composition and microstructure. Therefore, the primary approach is to ensure the correct corrosion inhibitor selection and application to prevent PWC. Although there has been considerable focus directed toward the effect of flow rate on PWC in inhibited carbon dioxide (CO2)-saturated environments, the consideration of a higher, localized turbulence over the weld material and the implications this has on PWC appears minimal. This paper considers this effect by reviewing the performance of a commercially available, film-forming oilfield corrosion inhibitor using a submerged impinging jet (SIJ). The dual nozzle arrangement of the SIJ allowed a carbon steel parent metal and a 1% Ni, 0.25% Mo weld material to be subjected to the same brine chemistry, but different flow conditions. The velocity over the parent metal was kept constant at 7 m/s while the weld material was subjected to velocities of 7, 8.8, and 11.4 m/s to simulate different severities of turbulence. Galvanic current and linear polarization resistance (LPR) measurements were used to assess the weld resistance to PWC. Although the weld was shown to be cathodic to the parent metal, increasing velocity and turbulence at the weld relative to the parent metal was found to reduce the galvanic current, suggesting increased susceptibility of the weld to corrosion. The addition of inhibitor at 100 ppm accentuated this effect and led to a reversal of the galvanic current when the relative velocities were 7 m/s and 11.4 m/s for the parent metal and weld, respectively. The paper discusses the power of this galvanic technique for prediction of the conditions conducive to accentuating PWC.

A cleaner approach towards deposition of CdS thin films by an electrochemical technique

AbstractCdS thin films have been deposited on Transparent Conducting Oxide (TCO, containing SnO2: F) coated glass substrates from aqueous sodium thiosulfate solutions, using the galvanic technique. A cadmium foil was used as a sacrificial anode and was the only source of Cd++ ions for CdS thin films, no external bias being used during film depositions. The films have been characterized using X‐ray diffraction, SEM, EDX, AFM and optical absorption studies. AAS analyses were carried out to determine the Cd content in solutions after film deposition. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Deposition of nano‐crystalline lead chalcogenide thin films using a simple electrochemical technique

AbstractNanocrystalline thin films of lead chalcogenides (PbS, PbSe and PbTe) were deposited on transparent conducting oxide (TCO) coated glass substrates at room temperature using a simple electrochemical (galvanic) technique, from suitable electrolytic solutions and without the application of any external bias. X‐ray characterization revealed that PbS, PbSe and PbTe thin films were all of cubic phase. The formation of nanocrystallites with dense and compact surface morphology was detected from FESEM and AFM measurements. The nanocrystalline films showed ‘blue shifted’ IR absorption. Hall measurements showed the materials to be p‐type in nature with carrier concentration in the range 1019 – 1020/cm3. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Crevice Corrosion of Grade-12 Titanium

Abstract The crevice corrosion of ASTM grade-12 titanium (Ti-12; 0.8 wt % Ni, 0.3 wt % Mo) has been studied in neutral 0.27 mol/L NaCl at temperatures up to 120°C using a galvanic coupling technique. The results were compared to those of similar experiments conducted on ASTM grade-2 titanium (Ti-2) specimens containing various amounts of iron impurity. The microstructural properties of the Ti-12 were determined by standard metallographic techniques and transmission electron microscopy. Penetration depth profiles were determined using metallographic and image analysis techniques. The redistribution of alloying elements (Ni, Mo) and impurities (Fe), and the location of absorbed hydrogen, were determined by secondary ion mass spectrometry (SIMS) imaging. The rate and extent of crevice propagation were significantly suppressed on Ti-12 compared to Ti-2, especially at higher temperature (120°C). Up to 97 % of the total amount of crevice propagation was driven by proton reduction inside the creviced area rather than by oxygen reduction outside the crevice. SIMS imaging shows that Ni accumulates on the corroding surface, probably in the form of residual Ti2Ni particles. Proton reduction is catalyzed on these particles, leading to their hydriding and an increase in the relative area of internal cathodes compared to available anodic surface area. This self-induced “cathodic modification” effect leads to repassivation of the corroded site before extensive damage can be sustained.