Electrochemically Fabricated Surface-Mesostructured CuNi Bimetallic Catalysts for Hydrogen Production in Alkaline Media

Ni-based bimetallic films with 20 at.% and 45 at.% Cu and mesostructured surfaces were prepared by electrodeposition from an aqueous solution containing micelles of P123 triblock copolymer serving as a structure-directing agent. The pH value of the electrolytic solution had a key effect on both the resulting Cu/Ni ratio and the surface topology. The catalytic activity of the CuNi films toward hydrogen evolution reaction was investigated by cyclic voltammetry (CV) in 1 M KOH electrolyte at room temperature. The Cu45Ni55 film showed the highest activity (even higher than that of a non-mesostructured pure Ni film), which was attributed to the Ni content at the utmost surface, as demonstrated by CV studies, as well as the presence of a highly corrugated surface.

Preparation and corrosion resistance properties of duplex stainless steel (00Cr22Ni6MnMoCu)

In the present paper, a new kind of duplex stainless steel (DSS, 00Cr22Ni6MnMoCu) was prepared. Cr30 was chosen as a comparison of microstructures and mechanical properties with 00Cr22Ni6MnMoCu. Corrosion tests with 3.5% NaCl solution and electrolytic solution for 00Cr22Ni6MnMoCu were carried out to analyze the corrosion pattern of test materials. It can be concluded that: (1) Austenitic and ferrite duplex stainless steel has an optimized phase distribution, high toughness and strength when the ratio of two-phase content is 1:1. (2) Corrosion tests show that the corrosion resistance of 00Cr22Ni6MnMoCu is 12 times compared to ferrite stainless steel Cr30. (3) Electrolytic corrosion tests show that for 00Cr22Ni6MnMoCu, the corrosion is caused by intergranular corrosion. For Cr30, it is mainly caused by pinholes. However, Cr30 has a poor corrosion resistance because of the presence of a large amount of carbides and their phase boundaries caused by the electric potential difference between the carbide and the matrix.

Recovery of Platinum Group Metals from Spent Automotive Catalysts Using Lithium Salts and Hydrochloric Acid

The recovery of platinum group metals (PGMs) from waste materials involves dissolving the waste in an aqueous solution. However, since PGMs are precious metals, their dissolution requires strong oxidizing agents such as chlorine gas and aqua regia. In this study, we aimed to recover PGMs via the calcination of spent automotive catalysts (autocatalysts) with Li salts based on the concept of “spent autocatalyst + waste lithium-ion batteries” and leaching with only HCl. The results suggest that, when Li2CO3 was used, the Pt content was fully leached, while 94.9% and 97.5% of Rh and Pd, respectively, were leached using HCl addition. Even when LiF, which is a decomposition product of the electrolytic solution (LiPF6), was used as the Li salt model, the PGM leaching rate did not significantly change. In addition, we studied the immobilization of fluorine on cordierite (2MgO·2Al2O3·5SiO2), which is a matrix component of autocatalysts. Through the calcination of LiF in the presence of cordierite, we found that cordierite thermally decomposed, and fluorine was immobilized as MgF2.

Scientific insights of electrochemical replacement approach to describe the origin of Pre-Columbian Peruvian gilded copper-based objects

Pre-Columbian Peruvian goldsmiths developed gilded copper-based objects by ancient techniques that require identification to propose conservation strategies. Lechtman H, conducted experiments to suggest that the electrochemical replacement was the gilding technique used by the Moche and Vicus cultural groups. Despite her remarkable achievement, the quantitative data provided by her is still open to discussion. This work focused on obtaining experimental data to recreate her protocol by introducing less gold precursor. Polished copper pieces were plated with an adherent gold film of up to 7.5 µm after immersing them into an electrolytic solution for 3 min and 6 min at 80 °C. Our results demonstrated that the electrochemical replacement technique gives rise to anodic regions in the plated objects. Further studies around the corrosion process that undergoes these heritage objects in burial and environmental conditions are suggested to determine their deterioration rate. Moreover, electroless and galvanic techniques should be explored in order to improve current approaches.

PHOTOPHYSICAL AND PHOTOCHEMICAL SYSTEMS WITH SEMICONDUCTORS FOR THE CONVERSION OF SOLAR ENERGY. A REVIEW

Electrochemical energy sources are an alternative to replace technology based on the burning of fossil fuels. In an elec-trochemical system the potential drop spreads over a very narrow region at an interphase, creating high electric fields.So, there are good technological reasons to study semiconductor / electrolyte interphases. Currently, one of the ways touse renewable resources is through photovoltaic technology that directly converts solar radiation into electrical energy.This technology is manufactured from semiconductors, generally silicon, following an extremely careful and expensivemanufacturing procedure. An option for photovoltaic devices is photoelectrochemical cells.These cells are made bythe contact of a semiconductor electrode with a solution, which can be easily prepared and offers the possibility oflow-cost manufacturing. Understanding how these devices work requires knowledge of the characteristics of semicon-ductors and how these materials behave in contact with an electrolytic solution and under illumination by sunlight. Thepresent work describes, through an updated review, the principles and applications of semiconductor electrodes as themain components in a photoelectrochemical solar cell (PEC), to carry out chemical reactions of technological interest.In addition, the elements that are required for the improvement in the performance and construction of the PEC are discussed.

The new formulation of the 0,05% sodium hypochlorite electrolytic solution for cutaneous use: reasons and advantages

Superinfection of skin lesions is quite common, and often delays wound recovery. Infection control plays therefore a key role in the management of skin lesions, requiring the use of specific antimicrobials. Among available agents, topic antiseptic drugs are currently recommended as a first-choice option, to be preferred to antibiotics, given the growing resistance to these drugs. Compared to antibiotics, antiseptic drugs have a wider spectrum of action, including bacteria, fungi, virus, protozoa, and prions. The ideal antiseptic for the management of an infected skin lesion is expected to be both highly effective and well tolerated, in order to promote the physiologic process of tissue restoration. Among available antiseptics, the 0,05% sodium hypochlorite electrolytic solution meets these criteria: the product proved to be effective in vitro and in animal experimental models against a wide range of microorganisms, besides exerting an anti-inflammatory action in the absence of any irritating, cytotoxic or carcinogenic adverse effect, and being useful in biofilm removal. Similarly, in several clinical trials, the 0,05% sodium hypochlorite electrolytic solution was demonstrated to be very effective and safe in the management of infected skin wounds: based on these results, this product should be strongly considered among the first-choice options for the disinfection of skin wounds. The new formulation, developed according to the latest reference standards for wound healing and in agreement with current guidelines, is qualitatively improved, with an expected positive impact in every field of clinical application and a subsequent benefit for treated patients.

Electrochemical Characterization of Cellulose Acetate/Chitosan Membrane in Presence and Absence of Nonionic Surfactant in Monovalent Electrolytic Solution

The influence of surfactant on cellulose acetate/chitosan membrane has been investigated. A basic approach to cellulose acetate/chitosan membrane is also mentioned. Nonionic surfactants are disrupted the normal permeability of the characteristic membrane. Electrochemical characterization such as conductance, flow, flux and permeability are measured in various concentrations of the electrolyte and surfactants. Membrane potential is determined by the combination of the properties of ions of the electrolyte, surfactant and membrane. The synthesized membrane was found to be cation selective with measured membrane potential found to be negative in all cases. The value of membrane potential was varying in different concentration of the electrolyte and surfactant. The Teorell Meyer and Sievers (TMS) theoretical method was employed for calculating the Transport number, perm selectivity and fixed charge density of the membrane by using the data of membrane potential across normal and surfactant modified membrane with electrolytic solution of NaCl. The variation of fixed density and perm selectivity also depends on the concentration of the electrolyte and surfactant (Tween 20 and Tween 60).

Diferenciação oxidativa em dispositivos temporários de ancoragem de Ti6Al4V e aço 316L – estudo piloto

The aim of this pilot study was to test the hypothesis that temporary anchoring devices (TADs) made of 316L steel are more resistant to corrosion even in fluorine environment than DATs manufactured in addition to titanium alloys, for this Potentiostat electrochemical measurements were performed. Materials and Methods: Four pieces of each material were tested in each test set, an application of Fusayama artificial saliva was used as an electrolytic solution in this study of in vitro corrosion, without fluorine in its composition and in a second moment with 1500ppM of fluorine in its composition. In the test, a cathodic polarization was performed by increasing this voltage for 5 minutes or until the corrosion pins were obtained. In artificial saliva containing up to 1500ppmF- this test was repeated with new samples of each material in artificial saliva solution without fluorine. Results: The results of the induction current scale were inserted into OriginPro8 software for making value graphs. As there was a small number of samples, in order not to violate the study’s reliability no statistical test was performed. Among all metal alloys currently used the Ti6Al4V alloy showed good resistance to corrosion in artificial saliva. However, the corrosion of these alloys occurs in contact with high fluorine concentration, unlike 316L steel alloy, which in addition to corrosion makes surface passivation.