Electrochemical studies of copper, copper-aluminium and copper-aluminium-silver alloys: Impedance results in 0.5M NaCl

Toward an Understanding of SEI Formation and Lithium Plating on Copper in Anode-Free Batteries

"Anode-free" batteries present a significant advantage due to their substantially higher energy density and ease of assembly in a dry air atmosphere. However, issues involving lithium dendrite growth and low cycling Coulombic efficiencies during operation remain to be solved. Solid electrolyte interphase (SEI) formation on Cu and its effect on Li plating are studied here to understand the interplay between the Cu current collector surface chemistry and plated Li morphology. A native interphase layer (N-SEI) on the Cu current collector was observed with solid-state nuclear magnetic resonance spectroscopy (ssNMR) and electrochemical impedance spectroscopy (EIS). Cyclic voltammetry (CV) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) studies showed that the nature of the N-SEI is affected by the copper interface composition. An X-ray photoelectron spectroscopy (XPS) study identified a relationship between the applied voltage and SEI composition. In addition to the typical SEI components, the SEI contains copper oxides (Cu _x O) and their reduction reaction products. Parasitic electrochemical reactions were observed via in situ NMR measurements of Li plating efficiency. Scanning electron microscopy (SEM) studies revealed a correlation between the morphology of the plated Li and the SEI homogeneity, current density, and rest time in the electrolyte before plating. Via ToF-SIMS, we found that the preferential plating of Li on Cu is governed by the distribution of ionically conducting rather than electronic conducting compounds. The results together suggest strategies for mitigating dendrite formation by current collector pretreatment and controlled SEI formation during the first battery charge.

Evaluation of pectin isolated from tomato peel waste as natural tin corrosion inhibitor in sodium chloride/acetic acid solution

The pectin from tomato peel waste (TPP) was employed as tin corrosion inhibitor with the aim to enhance the knowledge regarding the application of natural inhibitors, instead synthetic, and reducing the waste disposal for value-added biopolymers production. To evaluate the TPP anticorrosion activity the commercial apple pectin (CAP) was also utilised. The gravimetric tests show that the highest inhibitive impact (η) of 75.9 % (CAP) and 73.9 % (TPP) are gained at concentration of 20 g L^-1. By electrochemical, potentiodynamic polarization and impedance spectroscopy measurements, the maximum η (60.05-65.5 %) are reached at lower concentration (4 g L^-1), due to tendency of pectins to form viscous solution. The prominent decreases in current density with the shifts of potential in the cathodic direction revealed that pectins provided cathodic protection of tin surface. Similar inhibition impact of pectins, and fine agreement between applied methods confirmed their suitability against tin corrosion.

Development of Anti-Aging and Anticorrosive Nanoceria Dispersed Alkyd Coating for Decorative and Industrial Purposes

This study focuses on nano cerium oxide particles as alternative additives in solvent-based alkyd coatings in order to improve anticorrosive and anti-aging properties. The paint samples were formulated with cerium oxide micro and nanoparticles, and the coating quality characteristics were compared with coating formulated with commercial anticorrosive and UV-aging agents. Formulations were prepared with 3 wt % commercial anticorrosive agent as reference material (RP), 3 wt % cerium oxide microparticles (CER1), 3 wt % and 1% cerium oxide nanoparticles (CER2 and CER3), respectively. The basket milling technique with zirconium balls was used for the preparations of coatings and characterizations were performed by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and contact angle measurements. Improvement in the anticorrosive properties was proven with electrochemical impedance spectroscopy (EIS) and accelerated salt spray tests based on ISO 4628 Evaluation of Degradation of Coatings. Furthermore, physical and mechanical tests were run according to standard test methods for coatings and reported. Results showed that cerium oxide particles provide anticorrosive, UV defender, and self-cleaning effects, besides excellent physical resistance to alkyd coatings. The impact of cerium oxide nanoparticles was found to be stronger than those of the microparticles.

Corrosion inhibition of copper in aqueous chloride solution by 1H-1,2,3-triazole and 1,2,4-triazole and their combinations: electrochemical, Raman and theoretical studies

Triazoles are well-known organic corrosion inhibitors of copper. 1H-1,2,3-Triazole and 1,2,4-triazole, two very simple molecules with the only difference being the positions of the nitrogen atoms in the triazole ring, were studied in this work as corrosion inhibitors of copper in 50 mM NaCl solution using a set of electrochemical and analytical techniques. The results of electrochemical tests indicate that 1H-1,2,3-triazole exhibited superior inhibitor properties but could not suppress anodic copper dissolution at moderate anodic potentials (>+300 mV SCE), while 1,2,4-triazole, although it exhibited higher anodic currents, suppressed anodic copper dissolution at very anodic potentials. Density functional theory calculations were also performed to interpret the measured data and trends observed in the electrochemical studies. The computational studies considered either the inhibitors isolated in the gaseous phase or adsorbed onto Cu(111) surface models. From the calculations, the mechanisms of the inhibitive effects of both triazoles were established and plausible mechanisms of formation of the protective films on the Cu surface were proposed. The results of this study hold positive implications for research in the areas of catalysis, and copper content control in water purification systems.

Effect of Ag Addition on the Electrochemical Performance of Cu10Al in Artificial Saliva

In this work we proposed to evaluate the corrosion resistance of four different alloys by electrochemical techniques, a binary alloy Cu10Al, and three ternary alloys Cu10Al-xAg (x = 5, 10, and 15 wt.%) to be used like biomaterials in dental application. Biomaterials proposed were tested in artificial saliva at 37°C for 48 h. In addition, pure metals Cu, Al, Ag, and Ti as reference materials were evaluated. In general the short time tests indicated that the Ag addition increases the corrosion resistance and reduces the extent of localized attack of the binary alloy. Moreover, tests for 48 hours showed that the Ag addition increases the stability of the passive layer, thereby reducing the corrosion rate of the binary alloy. SEM analysis showed that Cu10Al alloy was preferably corroded by grain boundaries, and the Ag addition modified the form of attack of the binary alloy. Cu-rich phases reacted with SCN⁻ anions forming a film of CuSCN, and the Ag-rich phase is prone to react with SCN⁻ anions forming AgSCN. Thus, binary and ternary alloys are susceptible to tarnish in the presence of thiocyanate ions.

Enhanced corrosion inhibition properties of carboxymethyl hydroxypropyl chitosan for mild steel in 1.0 M HCl solution

CHPCS was synthesized and showed better corrosion inhibition than HPCS (corrosion inhibition of 95.3%); its corrosion inhibition mechanism is presented.

The polymeric nanofilm of triazinedithiolsilane capable of resisting corrosion and serving as an activated interface on a copper surface

It seems self-contradictory that a copper surface can resist corrosion and be activated concurrently.

A novel LTCC electrochemical cell construction and characterization: a detection compartment for portable devices

In this work we described for the first time the construction of a 25 μL electrochemical cell from low temperature co-fired ceramic (LTCC) material and carbon screen-printed electrode applicable in portable devices. Firstly, a carbon screen-printed electrode was prepared and characterized by cyclic voltammetry and scanning electron microscopy. Afterwards carbon polymeric film and metal pastes were dropped into the LTCC cell cavities in order to determine the device electrodes, and this arrangement was also electrochemically characterized. The great advantage of this promising device is the simple construction method and its widespread applicability in reusable portable devices.

Adsorption and desorption of bis-(3-sulfopropyl) disulfide during Cu electrodeposition and stripping at Au electrodes

The adsorption and desorption of bis-(3-sulfopropyl) disulfide (SPS) on Cu and Au electrodes and its electrochemical effect on Cu deposition and dissolution were examined using cyclic voltammetry stripping (CVS), field-emission scanning electron microscopy (FESEM), and X-ray photoelectron spectroscopy (XPS). SPS dissociates into 3-mercapto-1-propanesulfonate when it is contacted with Au and Cu electrodes, producing Cu(I)- and Au(I)-thiolate species. These thiolates couple with chloride ions and promote not only the reduction of Cu(2+) in Cu deposition but also the oxidation of Cu(0) to Cu(+) in Cu stripping. During Cu electrodeposition on the SPS-modified Au electrode, thiolates transfer from Au onto the Cu underpotential deposition (UPD) layer. The Cu UPD layer stabilizes a large part of the transferred thiolates which subsequently is buried by the Cu overpotential deposition (OPD) layer. The buried thiolates reappear on the Au electrode after the copper deposit is electrochemically stripped off. A much smaller part of thiolates transfers to the top of the Cu OPD layer. In contrast, when SPS preadsorbs on a Cu-coated Au electrode, almost all of the adsorbed SPS leaves the Cu surface during Cu electrochemical stripping and does not return to the uncovered Au surface. A reaction mechanism is proposed to explain these results.