Browsing by Author "Azpiroz, Patxi"
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Item Evaluation of the electrochemical performance of electrospun transition metal oxide-based electrode nanomaterials for water CDI applications(2019-06-20) Santangelo, Saveria; Pantò, Fabiola; Triolo, Claudia; Stelitano, Sara; Frontera, Patrizia; Fernández-Carretero, Francisco; Rincon, Inés; Azpiroz, Patxi; García-Luis, Alberto; Belaustegui, Yolanda; Tecnalia Research & Innovation; TECNOLOGÍAS DE HIDRÓGENO; VALORIZACIÓN DE RESIDUOSComposite fibrous materials based on (graphene-enriched) nitrogen-doped carbon/transition metal oxides were produced by electrospinning and their physicochemical properties were thoroughly investigated by a combination of characterisation techniques. The electrochemical behaviour of the electrodes prepared with them was evaluated in view of their use in the capacitive deionisation of saline water. The morphology of the materials reminded of usnea florida lichens, wheat ears, sea sponges and noodles and depended on the transition metal (Mn, Fe, Ti or Zn). The morphology and the relative amount (14.1–22.2 wt%) of the surface nitrogen and carbon-bonded oxygen functional species, beneficial to wettability and involving pseudocapacitive processes, had strong impact on the specific capacitance (43.7–67.4 F g−1, at 5 m V s−1 scan rate), whereas also the specific micropore volume (0.4–5.6 mm3 g−1) affected the effective areal capacitance of the electrodes (1.2–6.0 F m−2, at 5 mV s−1). Ion storage in the composite materials occurred via a mixed capacitive/pseudocapacitive process. Hence, increasing the content of the oxide (from 24.6 to 56.7 wt%), thanks to the fast-reversible redox reactions at or near surface it involves, partly compensated for the growing hindrance to diffusion encountered by the ions (hampered electrostatic adsorption) as the scan rate increased from 5 to 100 mV s−1.Item Fabrication and Characterization of a Novel Bioactive Poly(ether-ether-ketone) Scaffold for Bone Tissue Engineering (Poster)(MARY ANN LIEBERT, INC, 140 HUGUENOT STREET, 3RD FL, NEW ROCHELLE, NY 10801 USA, 2015-09) Olalde, Beatriz; Oyarbide, Joseba; Ayerdi, Ana; Azpiroz, Patxi; Fernandez, Ruben; Aizpurua, J.; Braceras, I.; Alvarez, Noelia; Briz, N.; Morin, F.O.It is widely accepted that the initial interactions between the cells and implant surface are crucial to clinical success. One of the promising alternative materials for tissue engineering is polyetheretherketone (PEEK) which has good chemical resistance and mechanical properties similar to those of human bones [1]. However, its hydrophobic and chemically inert surface limits local bone attachment [2]. Consequently, there have been efforts to enhance PEEK bone-implant integration by incorporating molecules (such as HA) or making it porous [3]. Regarding to the latest, this study aims to demonstrate a process that can greatly enhance the density and interconnectivity of a PEEK porous product (US2012323339) [4]. Moreover, a novel surface modification through wet-chemistry protocol has been developed for RGD and OGP (osteogenic growth peptide) grafting onto porous PEEK scaffolds (US2013172273) [5]. As a result, the production of porous structures manufactured by thermally induced phase separation technique (TIPS), in combination with particulate leaching method, offers the greatest potential to control pore size and porosity whilst achieving porosity higher than 80%. Besides, surface functionalization of porous PEEK scaffolds with RGD/OGP combination is shown to enhance osteoblast adhesion, proliferation and differentiation, according to the in vitro results. In conclusion, we have developed a convenient “click” chemistry procedure to modify PEEK surfaces with RGD and OGP10-14 molecules, while keeping the bulk properties of PEEK as well as its biocompatibility in terms of cytotoxicity. The improvement of the osteogenic activity of this novel material shows that can be appropriated for bone tissue engineering applications.Item Three-dimensional reduced graphene oxide decorated with iron oxide nanoparticles as efficient active material for high performance capacitive deionization electrodes(2021-05-15) Belaustegui, Yolanda; Rincón, Inés; Fernández-Carretero, Francisco; Azpiroz, Patxi; García-Luís, Alberto; Tanaka, David Alfredo Pacheco; Tecnalia Research & Innovation; VALORIZACIÓN DE RESIDUOS; TECNOLOGÍAS DE HIDRÓGENO; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSA three-dimensional reduced graphene oxide decorated with iron oxide nanoparticles (3D rGO-Fe2O3) material with a suitable porous structure was synthesised using a one-step hydrothermal process in order to fabricate novel electrodes for capacitive deionization (CDI) water desalination. The morphological and structural properties of the as-synthesised compounds were characterised by scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), Raman spectroscopy (RS), X-ray diffraction (XRD) and thermal gravimetric analysis (TGA). The CDI electrodes were electrochemically analysed by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). A maximum value of specific capacitance of 345 F g−1 was achieved at 5 mV s−1 scan rate using a NaCl 0.1 mol L−1 solution. The ion removal performance of the CDI electrodes was evaluated with NaCl solutions of different concentrations, showing electrosorption capacities as high as 945 mg g−1 for 11,700 mg L−1 (200 mmol L−1) NaCl solutions, which substantially surpasses results of other carbon-based CDI electrodes.