title: Deposition of Ni nanoparticles onto porous supports using supercritical CO2: effect of the precursor and reduction methodology.
abstract: The deposition of Ni nanoparticles into porous supports is very important in catalysis. In this paper, we explore the use of supercritical CO(2) (scCO(2)) as a green solvent to deposit Ni nanoparticles on mesoporous SiO2 SBA-15 and a carbon xerogel. The good transport properties of scCO(2) allowed the efficient penetration of metal precursors dissolved in scCO(2) within the pores of the support without damaging its structure. Nickel hexafluoroacetylacetonate hydrate, nickel acetylacetonate, bis(cyclopentadienyl)nickel, Ni(NO(3))2⋅6H(2)O and NiCl(2)⋅6H(2)O were tried as precursors. Different methodologies were used: impregnation in scCO(2) and reduction in H(2)/N(2) at 400°C and low pressure, reactive deposition using H(2) at 200-250°C in scCO(2) and reactive deposition using ethanol at 150-200°C in scCO(2). 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.
authors.affiliation: Department of Physical Chemistry I, Universidad Complutense, Ciudad Universitaria s/n, 28040 Madrid, Spain.
authors.forename: Jacobo
authors.initials: J
authors.lastname: Morère
authors.affiliation: Department of Physical Chemistry I, Universidad Complutense, Ciudad Universitaria s/n, 28040 Madrid, Spain.
authors.forename: Sergio
authors.initials: S
authors.lastname: Royuela
authors.affiliation: Department of Physical Chemistry I, Universidad Complutense, Ciudad Universitaria s/n, 28040 Madrid, Spain.
authors.forename: Guillermo
authors.initials: G
authors.lastname: Asensio
authors.affiliation: Department of Physical Chemistry I, Universidad Complutense, Ciudad Universitaria s/n, 28040 Madrid, Spain.
authors.forename: Pablo
authors.initials: P
authors.lastname: Palomino
authors.affiliation: Department of Physical Chemistry I, Universidad Complutense, Ciudad Universitaria s/n, 28040 Madrid, Spain.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Enciso
authors.affiliation: Department of Physical Chemistry I, Universidad Complutense, Ciudad Universitaria s/n, 28040 Madrid, Spain.
authors.forename: Concepción
authors.initials: C
authors.lastname: Pando
authors.affiliation: Department of Physical Chemistry I, Universidad Complutense, Ciudad Universitaria s/n, 28040 Madrid, Spain a.cabanas@quim.ucm.es.
authors.forename: Albertina
authors.initials: A
authors.lastname: Cabañas
keywords: mesoporous SiO2 SBA-15; mesoporous carbon; metal deposition; nickel nanoparticles; supercritical CO2