Person: Cervera Gabalda, Laura María
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Cervera Gabalda
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Laura María
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Ciencias
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InaMat2. Instituto de Investigación en Materiales Avanzados y Matemáticas
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0000-0003-1584-7645
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811405
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Publication Open Access Steering the synthesis of Fe3O4 nanoparticles under sonication by using a fractional factorial design(Elsevier, 2021) Echeverría Morrás, Jesús; Moriones Jiménez, Paula; Garrido Segovia, Julián José; Ugarte Martínez, María Dolores; Cervera Gabalda, Laura María; Garayo Urabayen, Eneko; Gómez Polo, Cristina; Pérez de Landazábal Berganzo, José Ignacio; Ciencias; Zientziak; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa; Gobierno de Navarra / Nafarroako GobernuaSuperparamagnetic iron oxide nanoparticles (MNPs) have the potential to act as heat sources in magnetic hyperthermia. The key parameter for this application is the specific absorption rate (SAR), which must be as large as possible in order to optimize the hyperthermia treatment. We applied a Plackett-Burman fractional factorial design to investigate the effect of total iron concentration, ammonia concentration, reaction temperature, sonication time and percentage of ethanol in the aqueous media on the properties of iron oxide MNPs. Characterization techniques included total iron content, Fourier Transform Infrared Spectroscopy, X-Ray Diffraction, High Resolution Transmission Electron Microscopy, and Dynamic Magnetization. The reaction pathway in the coprecipitation reaction depended on the initial Fe concentration. Samples synthesized from 0.220 mol L−1 Fe yielded magnetite and metastable precipitates of iron oxyhydroxides. An initial solution made up of 0.110 mol L−1 total Fe and either 0.90 or 1.20 mol L−1 NH3(aq) led to the formation of magnetite nanoparticles. Sonication of the reaction media promoted a phase transformation of metastable oxyhydroxides to crystalline magnetite, the development of crystallinity, and the increase of specific absorption rate under dynamic magnetization.Publication Open Access Magnetic-field-assisted photocatalysis of N-TiO2 nanoparticles(IEEE, 2023-09-04) Cervera Gabalda, Laura María; Garayo Urabayen, Eneko; Beato López, Juan Jesús; Pérez de Landazábal Berganzo, José Ignacio; Gómez Polo, Cristina; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2Nitrogen doped TiO2 nanoparticles were synthesized through solvothermal method employing Ti (IV) butoxide and HNO3 as precursors. Structural and optical characterizations confirm their nanometer nature (sizes around 10 nm) and the band-gap energy values in the UV range (3.2 eV). Nitrogen doping enhances the occurrence of optical Urbach tails extending towards the visible region. Visible photocatalytic performance (degradation of methyl orange) is correlated with maximum values in the magnetic susceptibility linked to a magnetic polarization of the anatase structure via defects (oxygen vacancies). The application of magnetic field provides a positive effect (acceleration in reaction kinetics) within the UV-Vis range.Publication Open Access Modulating photocatalytic activity of nitrogen doped TiO2 nanoparticles via magnetic field(Elsevier, 2024-07-30) Gómez Polo, Cristina; Cervera Gabalda, Laura María; Garayo Urabayen, Eneko; Beato López, Juan Jesús; Pérez de Landazábal Berganzo, José Ignacio; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate PublikoaThe effect of the magnetic field on the photocatalytic activity of TiO2-based nanoparticles is analyzed using a magnetically-assisted photoreactor with permanent magnets to generate a controlled uniform magnetic field, B (¿82 mT). Nitrogen doped TiO2 nanoparticles (sizes around 10 nm) were synthesized through a solvothermal method employing Ti(IV) butoxide and HNO3 (x = 0, 0.5, 1, 1.5 and 2 mL) as precursors and their structural, optical and magnetic properties were analyzed. Specifically, nitrogen doping is confirmed through Hard X-ray Photoelectron Spectroscopy (HAXPES) in those samples synthesized with low HNO3 concentrations (x = 0.5, 1). The correlation between spin polarization (magnetic susceptibility) and visible photocatalytic activity (methyl orange as a model organic pollutant) is particularly analyzed. Surprisingly, opposite effects of the magnetic field on the photocatalytic performance are found in the visible range (above 400 nm) or under UV-Vis irradiation (decrease and increase in the photocatalytic activity, respectively, under magnetic field). The Langmuir-Hinshelwood model allows us to conclude that the strong decrease in adsorption under the magnetic field (around 42 % for x = 0.5) masks the increase in the kinetic constant (close to 58 % for x = 0.5) related mainly to the effect of Lorentz forces on the reduction of the electron-hole recombination.Publication Open Access Fe-C nanoparticles obtained from thermal decomposition employing sugars as reducing agents(Elsevier, 2020) Cervera Gabalda, Laura María; Pérez de Landazábal Berganzo, José Ignacio; Garayo Urabayen, Eneko; Monteserín, María; Larumbe Abuin, Silvia; Martín, F.; Gómez Polo, Cristina; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias; Gobierno de Navarra / Nafarroako Gobernua; Universidad Pública de Navarra / Nafarroako Unibertsitate PublikoaThe aim of the work is to present a comparative analysis (structural and magnetic) of Fe-C nanocomposites obtained by the thermal decomposition of sugars (fructose, glucose and sucrose) employing FeCl3 as Fe3+ precursor. The thermal decomposition was followed through Thermogravimetry (TGA) and Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction, High Resolution Transmission Electron Microscopy (HRTEM) and Raman spectroscopy. The results indicate the reduction of Fe3+ under the performed thermal treatments and the achievement at high annealing temperatures of Fe-C nanostructures (coexistence of α-Fe and Fe3C nanoparticles surrounded by a carbon matrix). The magnetic characterization performed by dc SQUID magnetometry, shows an antiferromagnetic response in the initial stages of the decomposition process, and a ferromagnetic behavior linked to the Fe-based nanoparticles. The magnetic induction heating was analyzed through the ac hysteresis loops. Moderate Specific Absorption Rate (SAR) is obtained in Fe-C nanoparticles (~ 70 W/gFe), ascribed to the large nanoparticle size. The combination of porous carbon structure and ferromagnetic response of the Fe-C nanoparticles (i.e. local temperature increase under ac magnetic field) enlarge the emerging applications of these carbonaceous nanocomposites.