Rising attention has been recently addressed to the sorption properties of nanosized materials confined into different mesoporous matrices. The reduction to nanometer scale and the control of grain size of hydrides particles could, at least in principle, induce an enhancement of the hydrogen release and uptake through the tuning of thermodynamic and kinetic properties [1]. While grain growth and particle agglomeration can be avoided, ordered scaffolds can also allow to obtain homogeneous size distribution of active phases. Most of the works recently published concern C based porous materials [2], whereas less attention has been addressed to chemically different scaffolds which, in turn, could offer further opportunities in tuning the sorption properties of hydrogen rich phases. In this study we focus on the properties of nanosized hydrides confined into mesoporous scaffolds. Highly ordered Si-, C-, and transition metal-based mesoporous structures were prepared by sol-gel methods, and then embedded with mixtures of MgH2 and different complex borohydrides, by resorting to wet chemical impregnation and melting infiltration processes. Structural characterization was performed by X-Ray diffraction (XRD), small angle neutron scattering (SANS) and transmission electron microscopy (TEM), in order to estimate the efficiency of confinement pathways. The thermodynamics and kinetics of the hydrogen absorption and desorption processes, as well as the chemical nature of the released gas, were then investigated by high-pressure differential scanning calorimetric device (HP-DSC), Sievert apparatus (PCT-Pro2000) and mass spectroscopy (MS). Preliminary results indicate evident improvement in the sorption properties of the nanoconfined hydrides with regard to the corresponding materials in bulk conditions. The decrease of desorption temperatures in the multistep processes were tentatively related to the structural characteristics of the studied systems [3]. [1] M. Fichtner, Nanotechnology, 20, (2009) 204009. [2] P. Adelhelm, J. Gao, M.H.W. Verkuijlen, C. Rongeat, M. Herrich, P.J.M. van Bentum, O. Gutfleisch, A.P.M. Kentgens, K.P. de Jong, P.E. de Jongh, Chemistry of Materials 22 (2010) 2233-2238. [3] G. Mulas, R. Campesi, S. Garroni, E. Napolitano, C. Milanese, F. Dolci, E. Pellicer, D. Baró, A. Marini, Journal of Alloys and Compounds (2012) doi:10.1016/j.jallcom.2011.12.042

Ordered mesoporous scaffolds for the confinement of nanosized complex and metal hydrides / E., Tolu; F., Peru; R., Campesi; F., Dolci; C., Milanese; A., Marini; E., Pellicer; Garroni, M. D. B. a. r. ó. S.; Mulas, Gabriele Raimondo Celestino Ettore. - (2012). (Intervento presentato al convegno MH2012 - International Symposium on Hydrogen - Metal Systems tenutosi a Kyoto (Japan) nel 21-26 ottobre 2012).

Ordered mesoporous scaffolds for the confinement of nanosized complex and metal hydrides

MULAS, Gabriele Raimondo Celestino Ettore
2012-01-01

Abstract

Rising attention has been recently addressed to the sorption properties of nanosized materials confined into different mesoporous matrices. The reduction to nanometer scale and the control of grain size of hydrides particles could, at least in principle, induce an enhancement of the hydrogen release and uptake through the tuning of thermodynamic and kinetic properties [1]. While grain growth and particle agglomeration can be avoided, ordered scaffolds can also allow to obtain homogeneous size distribution of active phases. Most of the works recently published concern C based porous materials [2], whereas less attention has been addressed to chemically different scaffolds which, in turn, could offer further opportunities in tuning the sorption properties of hydrogen rich phases. In this study we focus on the properties of nanosized hydrides confined into mesoporous scaffolds. Highly ordered Si-, C-, and transition metal-based mesoporous structures were prepared by sol-gel methods, and then embedded with mixtures of MgH2 and different complex borohydrides, by resorting to wet chemical impregnation and melting infiltration processes. Structural characterization was performed by X-Ray diffraction (XRD), small angle neutron scattering (SANS) and transmission electron microscopy (TEM), in order to estimate the efficiency of confinement pathways. The thermodynamics and kinetics of the hydrogen absorption and desorption processes, as well as the chemical nature of the released gas, were then investigated by high-pressure differential scanning calorimetric device (HP-DSC), Sievert apparatus (PCT-Pro2000) and mass spectroscopy (MS). Preliminary results indicate evident improvement in the sorption properties of the nanoconfined hydrides with regard to the corresponding materials in bulk conditions. The decrease of desorption temperatures in the multistep processes were tentatively related to the structural characteristics of the studied systems [3]. [1] M. Fichtner, Nanotechnology, 20, (2009) 204009. [2] P. Adelhelm, J. Gao, M.H.W. Verkuijlen, C. Rongeat, M. Herrich, P.J.M. van Bentum, O. Gutfleisch, A.P.M. Kentgens, K.P. de Jong, P.E. de Jongh, Chemistry of Materials 22 (2010) 2233-2238. [3] G. Mulas, R. Campesi, S. Garroni, E. Napolitano, C. Milanese, F. Dolci, E. Pellicer, D. Baró, A. Marini, Journal of Alloys and Compounds (2012) doi:10.1016/j.jallcom.2011.12.042
2012
Ordered mesoporous scaffolds for the confinement of nanosized complex and metal hydrides / E., Tolu; F., Peru; R., Campesi; F., Dolci; C., Milanese; A., Marini; E., Pellicer; Garroni, M. D. B. a. r. ó. S.; Mulas, Gabriele Raimondo Celestino Ettore. - (2012). (Intervento presentato al convegno MH2012 - International Symposium on Hydrogen - Metal Systems tenutosi a Kyoto (Japan) nel 21-26 ottobre 2012).
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11388/55265
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