Polymer nanocomposites of polyaniline (PANI)-based metal oxides (SiO₂, CeO₂, and TiO₂A) were synthesized by in situ chemical oxidative polymerization by rapid mixing in a hydrochloric acid medium to evaluate and compare their performance as anti-corrosion coatings on commercial 1018 steel in a 3.5% NaCl medium. The anti-corrosion coatings were developed by dispersing synthesized nanocomposites on an alkydalic resin (AR) for their subsequent electrochemical characterization. X-ray diffraction (XRD) analyses show that PANI has a certain degree of crystallinity in its structure. The incorporation of metal oxide (MO) nanoparticles (NPs) into the polymer matrix was confirmed by scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM-EDS) analyses, while the interaction of nanoparticles with PANI was proven by Fourier transform infrared (FT-IR) and ultraviolet-visible (UV-vis). Thermogravimetric analysis (TGA) reveals that nanoparticles infer greater resistance to the thermal decomposition of PANI. Finally, the use of open circuit potential (OCP) study, Tafel curves, and electrochemical impedance spectroscopy (EIS) showed that coatings made with TiO₂A NPs exhibit the best anti-corrosion properties as compared to those synthesized with SiO₂ and CeO₂ NPs.

It is shown for the first time that the deep eutectic solvent, DES, formed by acetylcholine chloride and urea can be successfully used for Ag recovery from the cathode powder of spent silver oxide batteries. This DES performs two important functions namely, as selective leaching liquor to extract Ag(I) ions from the remaining Ag₂O, leaving intact the metallic Ag in the solid phase, and as electrolytic bath for silver electrodeposition onto a glassy carbon electrode or graphite. Using potentiodynamic and potentiostatic electrochemical measurements, it was possible to quantify both: the Ag(I) leaching rate and the concentration of Ag(I) ions leached after 24 h. From this value, it was possible to estimate that about 7% of the original mass of the cathode powder corresponds to Ag₂O and the rest to metallic Ag. Moreover, from potentiostatic current density transients, recorded during Ag electrodeposition, it was shown, for the first time in this DES, that this process occurs via multiple 3D nucleation with diffusion-controlled growth and valuable practical information i.e. the diffusion coefficient of Ag(I) ions in this media was quantified. From scanning electron microscopy images and energy-dispersive X-ray spectroscopy, the morphology and composition of the resulting deposits were characterized.

In this work, the leaching of the active material electrodes of spent alkaline batteries was carried out using a deep eutectic solvent formed by acetylcholine chloride-urea as leaching medium. From the leaching liquors of the cathode or the cathode/anode mix, the electrochemical formation of Mn or Mn-Zn alloy, onto a glassy carbon electrode, was respectively performed by means of cyclic voltammetry and chronoamperometry techniques. The analysis of the potentiostatic current density transients was done using of models that involve the three-dimensional nucleation and diffusion controlled growth of a) bimetallic phases [Díaz-Morales et al. J. Solid. State Electrochem. 17 (2013) 345–351], in the case of the Mn-Zn alloy and b) metallic nuclei, for Mn electrodeposition [Scharifker and Mostany, J. Electroanal. Chem., 177 (1984) 13–23]. From scanning electron microscopy and EDX, it was verified that the nuclei formed were composed of Mn, or the Mn-Zn alloy depending on the leaching liquors used.

Pd@Pd(OH) ₂ core–shell nanoparticles were potentiostatically electrodeposited onto a glassy carbon electrode, GCE, from Pd(II) ions dissolved in the reline deep eutectic solvent. It is shown that the GCE/Pd@Pd(OH) ₂ -modified electrode displays a high catalytic activity towards the methanol electrochemical oxidation reaction (MOR) in alkaline solution, revealing a mass activity of (2370 ± 450) mA mg _Pd ⁻¹ at the peak potential (for CVs recorded at 0.1 V s ⁻¹ ), much greater than those reported to date for other nanoparticles, namely: Pd, Cu ₁ Pd ₂ , Pd ₄ Ag ₁ , PdFe, PtPdPt, Pt or Pt ₂ Ru ₁ , synthesized by means of technically complicated, expensive and time-consuming methods or electrodeposited from aqueous media. In particular, the steady-state current reported for PdNPs electrodeposited from aqueous media towards MOR depicted values around 3 mA mg _Pd ⁻¹ , while those from DES (this work) reached values around 42 mA mg _Pd ⁻¹ . Furthermore, it is shown that the Pd@Pd(OH) ₂ nanoparticles displayed excellent poisoning tolerances, from 2 to 8, depending on the applied potential scan rate and anodic switching potential, which remains practically constant after 200 voltammetric cycles.

In an effort to examine the effect of the microstructural changes of the Ti6Al4V alloy, two heat treatments were carried out below (Ti6Al4V₈₀₀) and above (Ti6Al4V₁₀₅₀) its β-phase transformation temperature. After each treatment, globular and lamellar microstructures were obtained. Saos-2 pre-osteoblast human osteosarcoma cells were seeded onto Ti6Al4V alloy disks and immersed in cell culture for 7 days. Electrochemical assays in situ were performed using OCP and EIS measurements. Impedance data show a passive behavior for the three Ti6Al4V alloys; additionally, enhanced impedance values were recorded for Ti6Al4V₈₀₀ and Ti6Al4V₁₀₅₀ alloys. This passive behavior in culture medium is mostly due to the formation of TiO₂ during their sterilization. Biocompatibility and cell adhesion were characterized using the SEM technique; Ti6Al4V as received and Ti6Al4V₈₀₀ alloys exhibited polygonal and elongated morphology, whereas Ti6Al4V₁₀₅₀ alloy displayed a spherical morphology. Ti and O elements were identified by EDX analysis due to the TiO₂ and signals of C, N and O, related to the formation of organic compounds from extracellular matrix. These results suggest that cell adhesion is more likely to occur on TiO₂ formed in discrete α-phase regions (hcp) depending on its microstructure (grains).