Person:
Cabañas Poveda, Albertina

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First Name
Albertina
Last Name
Cabañas Poveda
URI
https://hdl.handle.net/20.500.14352/76101
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Químicas
Department
Química Física
Area
Química Física
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2015 - 20173
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Author: Morère, Jacobo ×

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Now showing 1 - 3 of 3
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    Designing nanocomposites using supercritical CO2 to insert Ni nanoparticles into the pores of nanopatterned BaTiO3 thin films
    (Journal of Materials Chemistry C, 2016) Castro, Alichandra; Morère, Jacobo; Cabañas Poveda, Albertina; Ferreira, Liliana; Godinho, Margarita; Ferreira, Paula; Vilarinho, Paula
    A new concept to prepare nanocomposite thin films is explored. Two chemical-based bottom-up steps are used to design functional films including: i) block copolymerassisted self-assembly of a porous matrix; and ii) impregnation of nanoparticles from a ferroic phase within the pores by supercritical CO2 deposition. Porous nanopatterned BaTiO3 thin films with ca. 17 nm of thickness are prepared using a cost-effective solgel solution containing a block copolymer and evaporation-induced self-assembly methodology. Hexagonal-arranged pores with diameter of ca. 95 nm, running perpendicularly to the substrate are filled with Ni nanoparticles using the supercritical fluid deposition technique from reduction of hydrated nickel nitrate in a supercritical CO2-ethanol mixture at 250 ºC. Small Ni nanoparticles with 21 ± 5 nm nm are selectively deposited inside the pores of the porous matrix. Structural and magnetic properties prove the coexistence of both phases.
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    Deposition of Ni nanoparticles onto porous supports using supercritical CO2: effect of the precursor and reduction methodology
    (Philosophical Transactions A, 2015) Morère, Jacobo; Royuela, Sergio; Asensio, Guillermo; Enciso Rodríguez, Eduardo; Pando García-Pumarino, Concepción; Cabañas Poveda, Albertina
    The deposition of Ni nanoparticles into porous supports is very important in catalysis. In this paper, we explore the use of supercritical CO2 (scCO2) as a green solvent to deposit Ni nanoparticles on mesoporous SiO2 SBA-15 and a carbon xerogel. The good transport properties of scCO2 allowed the efficient penetration of metal precursors dissolved in scCO2 within the pores of the support without damaging its structure. Nickel hexafluoroacetylacetonate hydrate, nickel acetylacetonate, bis(cyclopentadienyl)nickel, Ni(NO3)2⋅6H2O and NiCl2⋅6H2O were tried as precursors. Different methodologies were used: impregnation in scCO2 and reduction in H2/N2 at 400°C and low pressure, reactive deposition using H2 at 200–250°C in scCO2 and reactive deposition using ethanol at 150–200°C in scCO2. The effect of precursor and methodology on the nickel particle size and the material homogeneity (on the different substrates) was analysed. This technology offers many opportunities in the preparation of metal-nanostructured materials.
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    Green Preparation of PtRu and PtCu/SBA-15 Catalysts using Supercritical CO2
    (Journal of CO2 utilization, 2017) Sánchez Miguel, E.; Tenorio, María José; Morère, Jacobo; Cabañas Poveda, Albertina
    Sustainability is emerging as design criteria in catalysts production. Hence, the preparation of Pt bimetallic catalysts using supercritical CO2 (scCO2) as a green solvent is proposed. PtRu and PtCu nanoparticles (NPs) were deposited on mesoporous SiO2 SBA-15 by the reduction of Pt, Ru and Cu metalorganic precursor in scCO2. The simultaneous and sequential deposition of both metals was attempted using different reduction methodologies. The materials were characterized by X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and Energy-Dispersive X-ray analysis (EDX). XRD patterns matched closely that of cubic Pt. TEM images showed small NPs homogeneously distributed throughout the SBA-15 mesopores. Smaller particles were obtained when the reduction was performed in H2/N2 at low pressure. Sequential deposition of Cu or Ru in the first place followed by Pt yielded equimolar metal ratios. Samples prepared by sequential deposition were studied by Scanning Transmission Electron Microscopy (STEM). Composition profiles of the PtRu samples suggested an alloy structure. These catalysts were used in the hydrogenation of the renewable furfural in scCO2 at 80ºC. PtRu materials presented a high activity and selectivity to furfuryl alcohol.