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.

The hydration state and structural transformations of Ti films potentiostatically grown in 0.1 M NaOH are characterized utilizing EIS, Mott-Schottky and XPS techniques. Variations presented in the density of donors, the flatband potential and the fraction of species measured by XPS, in the region of characterization of these films are associated with changes in the ratio of different Ti sub-oxides within the passive film. Oxygen and hydroxyl vacancies and their respective formation rate constants are estimated from EIS spectra fits with a modified Point Defect Model. A consistent behavior is observed for the hydration state and structural transformations of the films as a function of potential. Films anodized at less positive potentials than 1.17 V vs SCE present higher hydroxyl vacancy diffusivities (e.g higher film hydration) and a heterogeneous mixture of titanium sub-oxides, whereas the opposite behavior is observed for films formed at more positive potentials than 1.17 V vs SCE, where the hydroxyl vacancy diffusivities decrease by one order of magnitude and the oxygen vacancy diffusivities increase three times. Thus, films anodized at more positive potentials present a higher dehydration, are more homogeneous and mainly composed of TiO₂.

The coordination polymer Zn₃Na₂[Fe^II(CN)₆]₂ has an open porous framework that is stable in acidic and neutral aqueous solutions and appears to be an attractive solid for investigation as a material for sodium ion-based batteries. The easy ion exchange of Na⁺ by bigger cations (such as K⁺, Rb⁺ and Cs⁺) and the existence of the oxidized species Zn₃[Fe^III(CN)₆]₂ (as a stable phase) support the present study of the redox reaction and stability in aqueous media under electrochemical conditions for all the series, including the effect of the accompanying cation on the mobility of sodium in the framework. When a study was carried out in a solution of sodium ions, in the material structure K⁺ and Rb⁺ were progressively displaced by the sodium ions, which was ascribed to their higher mobility. However, when an experiment was conducted using a solution containing Cs⁺ or in an aqueous solution of NaNO₃, from Zn₃Cs₂[Fe^II(CN)₆]₂, the mixed composition Zn₃NaCs[Fe^II(CN)₆]₂ was formed. The results discussed here are supported by the electrochemical and spectroscopic measurements. Galvanostatic experiments on the Zn₃Cs₂[Fe^II(CN)₆]₂ system in a solution of sodium ions revealed a capacity retention of 75% during 40 charge/discharge cycles.