Influence of Ce(IV) ions amount on the electrochemical behavior of hybrid films in 0.1 mol L-1 NaCl solution

Abstract

In this work, the influence of ceric ions (Ce(SO4)2) addition to the hydrolysis solution on the corrosion protection afforded by organic-inorganic hybrid coating obtained from tetraethoxysilane (TEOS) and 3-methacryloxy-propyl-trimethoxysilane (MPTS) to a carbon steel substrate in 0.1 mol L-1 NaCl solution was studied. Open circuit potential (EOC) and electrochemical impedance spectroscopy (EIS) experiments were carried out and showed that the protection afforded by the organic-inorganic hybrid coating was extremely dependent on the Ce4+ ions amount. These results were in close agreement with optical microscopy observation of the degrading surfaces, both procedures showing that more protective coating was produced when 500 ppm of Ce4+ ions were added to the organic-inorganic hybrid solution. The chemical state of the organic-inorganic hybrid coating investigated by X-ray photoelectron spectroscopy (XPS) indicated that the addition of Ce4+ ions enhances the polycondensation degree of the organic-inorganic hybrid coating leading to a denser siloxane (Si-O-Si) network. A strategy using laser-induced breakdown spectroscopy (LIBS) and UV-Vis spectrometry was set up in order to verify, respectively, the presence of Ce ions within the coating structure and its oxidation state. LIBS results confirmed the incorporation of Ce ions in the coating, which, according to UV-Vis measurements, are mainly in the (IV)-oxidation state.

Phosphate-based Ce(IV) Ion-Imprinted Polymers for Separation of Berkelium: Testing the Homologue Imprinting Approach for Heavy Actinides

“…This is similar to that reported in the literature. , Upon addition of KBrO 3 to this solution, the sharp peak at 339 nm was replaced with a broad band encompassing three absorbance peaks at 354, 401, and 440 nm as shown in Figure Ib. This is attributed to the charge transfer transition from oxygen to the d-Ce­(IV) orbital. , This shows that with the addition of KBrO 3 , the conversion of Ce­(III) to Ce­(IV) is successfully accomplished.…”

“…This is attributed to the charge transfer transition from oxygen to the d-Ce(IV) orbital. 49,50 This shows that with the addition of KBrO 3 , the conversion of Ce(III) to Ce(IV) is successfully accomplished.…”

Synergistic Effects of Organic Ligands and Visible Light on the Reductive Dissolution of CeO2 Nanoparticles: Mechanisms and Implications for the Transformation in Plant Surroundings

“…After an extended period of irradiation following the initial 74 h, we noted that Ce 3+ concentration at pH 4.0 gradually decreased to undetectable (Figure b). Correspondingly, the peak of Ce 3+ in the UV–vis spectra reached its maximum at 74 h and then became flattened with the appearance of a new peak between 270 and 300 nm, which could be assigned to Ce­(IV) (Figure S8b) and suggested the reoxidation of Ce 3+ . An increase in pH from 4.0 to 5.6 was observed during 74 h incubation.…”

“…Correspondingly, the peak of Ce 3+ in the UV−vis spectra reached its maximum at 74 h and then became flattened with the appearance of a new peak between 270 and 300 nm, which could be assigned to Ce(IV) (Figure S8b) and suggested the reoxidation of Ce 3+ . 52 An increase in pH from 4.0 to 5.6 was observed during 74 h incubation. The possibility of Ce(OH) 3 precipitation was eliminated, as the majority of Ce(III) existed as dissolved Ce 3+ species within the pH range of 4.0−5.6 (Figure S10).…”