Fully Biodegradable Biocomposites with High Chicken Feather Content

The aim of this work was to develop new biodegradable polymeric materials with high loadings of chicken feather (CF). In this study, the effect of CF concentration and the type of biodegradable matrix on the physical, mechanical and thermal properties of the biocomposites was investigated. The selected biopolymers were polylactic acid (PLA), polybutyrate adipate terephthalate (PBAT) and a PLA/thermoplastic copolyester blend. The studied biocomposites were manufactured with a torque rheometer having a CF content of 50 and 60 wt %. Due to the low tensile strength of CFs, the resulting materials were penalized in terms of mechanical properties. However, high-loading CF biocomposites resulted in lightweight and thermal-insulating materials when compared with neat bioplastics. Additionally, the adhesion between CFs and the PLA matrix was also investigated and a significant improvement of the wettability of the feathers was obtained with the alkali treatment of the CFs and the addition of a plasticizer like polyethylene glycol (PEG). Considering all the properties, these 100% fully biodegradable biocomposites could be adequate for panel components, flooring or building materials as an alternative to wood–plastic composites, contributing to the valorisation of chicken feather waste as a renewable material.This work was supported by KaRMA2020 project. This project has received funding from the European Union’s Horizon 2020 Research and Innovation program under Grant Agreement n° 723268

Flexible Biocomposites with Enhanced Interfacial Compatibility Based on Keratin Fibers and Sulfur-Containing Poly(urea-urethane)s

Feathers are made of keratin, a fibrous protein with high content of disulfide-crosslinks and hydrogen-bonds. Feathers have been mainly used as reinforcing fiber in the preparation of biocomposites with a wide variety of polymers, also poly(urea-urethane)s. Surface compatibility between the keratin fiber and the matrix is crucial for having homogenous, high quality composites with superior mechanical properties. Poly(urea-urethane) type polymers are convenient for this purpose due to the presence of polar functionalities capable of forming hydrogen-bonds with keratin. Here, we demonstrate that the interfacial compatibility can be further enhanced by incorporating sulfur moieties in the polymer backbone that lead to new fiber-matrix interactions. We comparatively studied two analogous thermoplastic poly(urea-urethane) elastomers prepared starting from the same isocyanate-functionalized polyurethane prepolymer and two aromatic diamine chain extenders, bis(4-aminophenyl) disulfide (TPUU-SS) and the sulfur-free counterpart bis(4-aminophenyl) methane (TPUU). Then, biocomposites with high feather loadings (40, 50, 60 and 75 wt %) were prepared in a torque rheometer and hot-compressed into flexible sheets. Mechanical characterization showed that TPUU-SS based materials underwent higher improvement in mechanical properties than biocomposites made of the reference TPUU (up to 7.5-fold higher tensile strength compared to neat polymer versus 2.3-fold). Field Emission Scanning Electron Microscope (FESEM) images also provided evidence that fibers were completely embedded in the TPUU-SS matrix. Additionally, density, thermal stability, and water absorption of the biocomposites were thoroughly characterized.This work was supported by KaRMA2020 project. This project has received funding from the European Union’s Horizon 2020 Research and Innovation program under Grant Agreement n 723268

The effect of the evaporation rate on electrochemical measurements with paper-based analytical devices and its minimisation by enclosure with adhesive tape

In this work, the effect of liquid evaporation on electrochemical measurements with electrochemical paper-based devices (ePADs) is studied. The time evolution of cyclic voltammograms of ferricyanide is used to study the effect of liquid evaporation under different conditions of relative humidity and air currents. Moreover, the enclosure of ePAD channels with adhesive tape is evaluated in terms of minimising the evaporation, as well as increasing the sensitivity in the electrochemical determination of horseradish peroxidase in long-term assays.This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 760876

Enhanced photostability and sensing performance of graphene quantum dots encapsulated in electrospun polyacrylonitrile nanofibrous filtering membranes

We report a method to encapsulate graphene quantum dots (GQD) in polyacrylonitrile (PAN) nanofibrous membranes to manufacture robust filtering membranes by electrospinning. GQD-PAN membranes with different nanofiber diameter were prepared tuning the electrospinning parameters, all exhibiting the characteristic fluorescence fingerprint of the GQD probes. The photoluminescence (PL) stability of GQD embedded in the PAN fibers was significantly enhanced with respect to that of water dispersed GQD luminescent probes. The PL of GQD-PAN filtering membranes showed remarkable time stability, both stored dry and immersed in phosphate buffer solutions (PBS), as well as exposed to continuous light irradiation. However, the PL intensity of GQD-PAN membranes was irreversibly quenched by highly oxidant free chlorine solutions. Thus, electrospun GQD-PAN membranes exhibited excellent performance as turn-off fluorescence sensing platforms for free chlorine detection in PBS 0.1 M pH 7. The analytical performance of GQD-PAN membranes was comparable to that of GQD solutions with optimal concentrations, displaying a fast (no need of incubation time) and linear response to chlorine concentration in the 10–600 μM range, a low detection limit of 2 μM, high sensitivity, reproducibility and selectivity. Moreover, the sensing performance of the membranes was very stable after being immersed in PBS for months, outperforming the stability of GQD solutions

Functionalization of Cellulose Nanocrystals in Choline Lactate Ionic Liquid

Cellulose nanocrystals (CNCs) are valuable nanomaterials obtained from renewable resources. Their properties make them suitable for a wide range of applications, including polymer reinforcement. However, due to their highly hydrophilic character, it is necessary to modify their surface with non-polar functional groups before their incorporation into a hydrophobic polymer matrix. In this work, cellulose nanocrystals were modified using a silane coupling agent and choline lactate, an ionic liquid derived from renewable resources, as a reaction medium. Modified cellulose nanocrystals were characterized by infrared spectroscopy, showing new peaks associated to the modification performed. X-ray diffraction was used to analyze the crystalline structure of functionalized cellulose nanocrystals and to optimize the amount of silane for functionalization. Poly(lactic acid) (PLA) nanocomposites containing 1 wt % of functionalized cellulose nanocrystals were prepared. They were characterized by field-emission scanning electron microscopy (FE-SEM) and mechanical tests. The use of choline lactate as reaction media has been shown to be an alternative method for the dispersion and silanization of the cellulose nanocrystals without the addition of an external catalyst.Financial support from the European Commission (FP7 Program, ECLIPSE project FP7-NMP-280786) is gratefully acknowledged

Platinum-catalyzed Nb-doped TiO2 and Nb-doped TiO2 nanotubes for hydrogen generation in proton exchange membrane water electrolyzers

This paper studies the catalytic activity of Pt deposited onto Nb-doped titania supports toward the hydrogen evolution reaction (HER). New catalysts based on Nb-doped TiO2 nanoparticles (nNb-TiO2) and Nb-doped TiO2 nanotubes (nNb-TNTs), with n in the range 3-10 at % (Nb+Ti), were synthesized. The specific surface areas of nNb-TNTs were 250−300 m2g-1, about three times higher than those of nNb-TiO2. X-ray diffraction showed the Nb incorporation into the TiO2 lattice with its consequent lattice expansion. The X-ray photoelectron spectra of Pt deposited onto Nb-doped titania revealed a negative charge accumulation on Pt, thus denoting strong metal-support interaction. The electrochemical characterization in acidic media showed that Pt supported on nNb-TiO2 and nNb-TNTs presented better activity towards the HER than that of Pt deposited onto the un-doped supports and commercial Pt on carbon. The best performance was obtained with a small Nb doping of 3 at %

High performance carbon free bifunctional air electrode for advanced zinc-air batteries

Secondary zinc-air batteries (ZABs) offer a promising alternative for the future of sustainable energy storage. However, the current capability of secondary ZABs is far from satisfactory. The limitations for achieving high reversibility are mainly related to the bifunctional air electrodes as it severely hampers practical applications and commercialization of secondary ZABs. Many efforts have been devoted to the development of efficient and corrosion resistant bifunctional electrocatalysts towards oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). In ZABs, carbon is commonly used as conductive additive, however, it has been observed that carbon materials are not resistant to the high positive voltages applied in electrical recharge. In this work, the use of metallic nickel as alternative conductive additive in bifunctional air electrodes is explored and compared with carbon nanotubes (CNT). We demonstrate that the chemical resistance of CNT does not limit the electrode performance; but the density of the additive as well as its interaction with the active material is crucial for achieving long cycle life. The use of Ni as conductive agent in secondary ZABs boosted the cycle life by delivering more than 2,400 cycles, in contrast to the 88 cycles delivered by the analogous carbon-based battery.This work was supported by CDTI (ALMAGRID of the “CERVERA Centros Tecnológicos” program, CER-20191006), the Basque Country Government (CIC energiGUNE’20 of the ELKARTEK program, N° Exp. KK-2020/0078), the European Commission through the project ZABCAT “A New Zn-Air Battery Prototype to Overcome Cathode Degradation Through Catalyst Confinement” (grant agreement 966743) and the Ministerio de Ciencia e Innovación through the project AVANZA “Advanced Zn-Air Battery Prototype for the Energy Transition Horizon” (TED2021-131451B-C22). N. Ortiz-Vitoriano thanks Ramon y Cajal grant (RYC-2020-030104-I) funded by MCIN/AEI/10.13039/501100011033 and by FSE invest in your future

Acoustic emission as a reliable technique for filiform corrosion monitoring on coated AA7075-T6: Tailored data processing

Acoustic emission (AE) was used for in-situ filiform corrosion (FFC) monitoring on coated AA77075-T6. The analysis of AE data using DBSCAN as clustering algorithm (validated by Bhattacharyya Coefficients´ evaluation) has revealed the presence of three clusters (out of four) related to phenomena involved in the FFC mechanism: metal-coating interface delamination due to opening (tensile), sliding (shear) and mixed mode enclosing both previous ones. The peak frequency was found to be the most relevant descriptor for clustering by using Random Forest classifier, and the correlation with the dominant frequencies range was validated obtaining the Power Spectrum Density of the AE signals.This work has been funded by the European Commission under the Horizon 2020 framework (H2020-CS2-CFP09-2018-02) within the U-Cross project (Grant Agreement 864905) in collaboration with Dassault Aviation, INSA Lyon, Mistras Group, Titania Ensayos y Proyectos Industriales and Université Bourgogne-Franche-Comté. J.M. Vega also would like to acknowledge the support of RYC2021-034384-I by Ministerio de Ciencia e Innovació

Supporting IrO2 and IrRuOx nanoparticles on TiO2 and Nb-doped TiO2 nanotubes as electrocatalysts for the oxygen evolution reaction

IrO2 and IrRuOx (Ir:Ru 60:40 at%), supported by 50 wt% onto titania nanotubes (TNTs) and (3 at% Nb) Nb-doped titania nanotubes (Nb-TNTs), as electrocatalysts for the oxygen evolution reaction (OER), were synthesized and characterized by means of structural, surface analytical and electrochemical techniques. Nb doping of titania significantly increased the surface area of the support from 145 (TNTs) to 260 m2 g−1 (Nb-TNTs), which was significantly higher than those of the Nb-doped titania supports previously reported in the literature. The surface analytical techniques showed good dispersion of the catalysts onto the supports. The X-ray photoelectron spectroscopy analyses showed that Nb was mainly in the form of Nb(IV) species, the suitable form to behave as a donor introducing free electrons to the conduction band of titania. The redox transitions of the cyclic voltammograms, in agreement with the XPS results, were found to be reversible. Despite the supported materials presented bigger crystallite sizes than the unsupported ones, the total number of active sites of the former was also higher due to their better catalyst dispersion. Considering the outer and the total charges of the cyclic voltammograms in the range 0.1-1.4 V, stability and electrode potentials at given current densities, the preferred catalyst was IrO2 supported on the Nb-TNTs. The electrode potentials corresponding to given current densities were between the smallest ones given in the literature despite the small oxide loading used in this work and its Nb doping, thus making the Nb-TNTs-supported IrO2 catalyst a promising candidate for the OER. The good dispersion of IrO2, high specific surface area of the Nb-doped supports, accessibility of the electroactive centers, increased stability due to Nb doping and electron donor properties of the Nb(IV) oxide species were considered the main reasons for its good performance

Assessing the Effect of CeO2 Nanoparticles as Corrosion Inhibitor in Hybrid Biobased Waterborne Acrylic Direct to Metal Coating Binders

CeO2 nanoparticles were incorporated in waterborne binders containing high biobased content (up to 70%) in order to analyze the anticorrosion performance for direct to metal coatings. Biobased binders were synthesized by batch miniemulsion polymerization of 2-octyl acrylate and isobornyl methacrylate monomers using a phosphate polymerizable surfactant (Sipomer PAM200) that lead to the formation of phosphate functionalized latexes. Upon the direct application of such binders on steel, the functionalized polymer particles were able to interact with steel, creating a thin phosphatization layer between the metal and the polymer and avoiding flash rust. The in situ incorporation of the CeO2 nanoparticles during the polymerization process led to their homogeneous distribution in the final polymer film, which produced outstanding anticorrosion performance according to the Electrochemical Impedance Spectroscopy measurements. In fact, steel substrates coated with the hybrid polymer film (30–40 µm thick) showed high barrier corrosion resistance after 41 days (~1000 h) of immersion in NaCl water solution and active inhibition capabilities thanks to the presence of the CeO2 nanoparticles. This work opens the door to the fabrication of sustainable hybrid anticorrosion waterborne coatings.This research was funded by the Spanish Government, grant numbers MINECO CTQ-2017-87841-R and CER-20191003, and by the Basque Government “Grupos Consolidados del Sistema Universitario Vasco”, grant number IT999-16