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Hydrogels are attracting interest in the field of bioelectronics due to their ability to serve as coatings on electrodes, improving the electrochemical interface, addressing the mechanical mismatch, and offering potential for localized drug or cell delivery. Challenges persist in integrating hydrogels with electrodes typically composed of metals and/or organic semiconductors. Here, an electrochemically driven method is introduced for direct growth of chitosan hydrogels onto poly(3,4‐ethylenedioxythiophene) (PEDOT) surfaces. The growth of ionic gelation chitosan is triggered by electrical release of a specific dopant, tripolyphosphate (TPP), from PEDOT. As a result, chitosan hydrogels grow directly from the PEDOT surface and firmly attach to it. Although this process temporarily reduces PEDOT to the benzoid structure, its unique electroactivity allows for reversible conversion to the quinoid structure after chitosan hydrogel assembly. Once assembled, the chitosan hydrogel coating can be further functionalized. The introduction of covalent cross‐links and incorporation of additional interpenetrating polymer networks (IPNs) are explored. Electrochemical characterization reveals that an interface with favorable properties is formed between PEDOT and ionic‐covalent chitosan, functionalized with a PEDOT IPN. The electroactivity of the proposed method surpasses any other PEDOT/chitosan system reported in the literature. These results underscore the potential of this material for bioelectronics applications. [ABSTRACT FROM AUTHOR]

In the current study, the synthesis of hematite (α-Fe2O3) at different temperatures (750 and 900 °C), and reduced graphene oxide (rGO), obtained from an adaptation to the Hummers's method, was evaluated. These materials were characterized by X-ray diffraction, Raman spectroscopy, Fourier-transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, among others. The deposition of samples on the conductive surface of tin-doped indium oxide coated glass substrate, was performed by the Layer-by-Layer technique. The films were prepared with 1- and 4-bilayers α-Fe2O3, using a cationic polyelectrolyte diallyldimethylammonium chloride (PDDA) or rGO. It was observed that the rGO/α-Fe2O3 films presented higher photocurrent and less resistivity when compared to the PDDA/α-Fe2O3 films. The largest photocurrent was obtained with the 4-bilayers rGO/α-Fe2O3 at 900 °C film, with 2.15 µA cm−2. In addition, a kinetic study for photoelectrocatalytic decolorization of the methylene blue dye under visible light was performed. The electrode that showed the greatest photoelectroactivity was the 4-bilayers rGO/α-Fe2O3 at 900 °C film, resulting in kobs = 11.90 × 10−3 min−1 and about 78% decolorization after 120 min. [ABSTRACT FROM AUTHOR]

This paper describes the use of Al2O3/ZrO2 mixed oxides synthesized by sol-gel process with different amounts of ZrO2 (5%, 10%, 15% and 20% by mass) in the Al2O3 matrix and different temperatures of calcination, such as interesting inhibitor materials of corrosive processes of SAE 1020 steel. The materials were characterized by Infrared Spectroscopy Fourier Transform (FTIR) and X-Ray Diffraction (XRD) techniques. FTIR spectra show the typical Al-O and Zr-O bonds vibrations in the mixed oxides. The XRD patterns of the samples calcined at 800 °C and 1000 °C shows the ZrO2 tetragonal and γ-Al2O3 face-centered cubic (FCC) phases. The corrosion tests showed that the SAE 1020 steel covered with mixed oxides have an anodic passive region, thereby inhibiting the corrosive processes on the metal surface. Furthermore, the found values for steel coated with mixed oxide synthesized indicate a decrease in corrosion potentials (Ecor) and corrosion current (icor). With respect to different samples of mixed oxides, the sample with 20 % of ZrO2 in the Al2O3 matrix proved to be the best inhibitor of steel corrosion, with the lowest values of corrosion potential and corrosion current, - 1.32 V and 0.31 μA cm-2, respectively. [ABSTRACT FROM AUTHOR]