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FISR project TEPSI:Nanostructured Mg for fast and reliable hydrogen deliveryFISR project TEPSI:Nanostructured Mg for fast and reliable hydrogen delivery
ABSTRACT: The tailoring of hydrogen sorption kinetics of Mg hydride represents one of the most challenging opportunities for a safe storage and reliable use of hydrogenin on board applications. The main technological limitations required for most applications, represented by the slow desorption kinetics at the too high desorptiontemperatures, can overcome by nanostructured hydrides and catalysts. By means the support of detailed characterization of both functional properties andmicrostructure [1,2], the aim of the TEPSI project is to study the effect of nanostructures on the performances of the Mg-based hydrides and to perform newcomplementary synthesis methods. In particular, Mg-based nanostructured materials (thin films or nanopowders) are prepared by (1) Sputtering techniques, a suitable
SPUTTERING TECHNIQUENb-doped Mg produced
by r.f. magnetron sputtering in the range of 6x10-4 < [Nb/Mg] < 5x10-2):
STRUCTURAL
and KINETIC ANALYSIS
TEM images
before and after
H2 sorption
cycling of Nb-
doped Mg:
the material
passes from a
micro-
to a nano-
structure
By the Sievert Apparatus
we study the sorption
performances
of the catalyzed materials
and determine the Activation
Energy and Rate Limiting
Step of the reaction
Lower Temperature!
EXAFS measurements
on Nb-doped Mg confirmed
the presence of Nb atomic
level clusters (~ 20nm) in as
deposited sample, the
presence of NbH in
hydrogenated samples and
their size reduction after the
desorption reaction
Nb-doped Mg
As-deposited Desorbed
Sample ττττ1/2 (sec)Ea (kJ mol-1) Rate Limiting Step
pure MgH23250±50 141±5 Nucleation
Mg + 0,006 at.% Nb 2390±50 140±5 Diffusion +
Nucleation
Mg + 1 at.% Nb 290±10 78±5 Diffusion +
Nucleation
Mg + 2-5 at.% Nb 110±10 51±5 Diffusion
Mg NANOPARTICLES by INERT GAS CONDENSATION:
DTA and H2 desorption curves of MgH2 with different Nb concentration; T: 623K
Faster Kinetics! Lower temperature!
Mg 0,02 mbar He Mg 2 mbar He
Typical TEM images of the Mg
nanoparticles prepared by IGC apparatus
at different He pressure associated to DSC
curves of the respective samples. By
decreasing the He pressure during the
synthesis process, the average
nanoparticles size decrease and the
desorption performances improve.
IGC
apparatus
SE 1kV
SE 20kV
BSE 20kV
An original method to study the
microstructure of Mg-MgH2
cross-sectional samples at high
spatial resolution has been set
up and successfully tested on
partially desorbed powders. The
method is based on the
difference in the electronic
structure between the two
phases which gives rise to a
contrast observable in low
voltage SEM images.
With Fe catalyst
well visible Mg-MgH2 phase
distribution in low energy SE
Catalyzing particles well
observed in high energy BSE
Complete microstructural
information by the
comparison of high energy
BSE and
low primary energy SE
We can observe mixed
microstructures extending
over almost the whole sample
Without catalyst:
Low energy SE is
able to reveal
microstructures
Images BSE confirm
the results
Charging artefacts in
high voltage SE
images
We observe a
coarse
microstructure and a
finer microstructure
at Mg /MgH2
interface
A.Montone1, A.Aurora1, C.Battaglin2, N.Bazzanella3, E.Bonetti4, R.S.Brusa3, E.Callini4, M.Celino1, R.Checchetto3, V.Contini1, S.Giusepponi1, G. Mattei5, C. Maurizio6, P. Mazzoldi5,
P.Mengucci7, A.Miotello3, M.R.Mancini1, D.Mirabile Gattia1 , L.Pasquini4, N.Patel3, E.Piscopiello1*, C. Sada 5, G. Siviero 5, M.Vittori-Antisari11ENEA, Dipartimento FIM, C.R.Casaccia, Via Anguillarese, 301, 00123 Roma; 1*ENEA, Dipartimento FIM, C.R.Brindisi, S.S. 7 “Appia”, Km 706, 72100 Brindisi; 2Dipartimento di Chimica Fisica, Università Ca’ Foscari di Venezia, Calle Larga S. Marta, 30100 Venezia;3Dipartimento di Fisica, Università degli Studi di Trento, 38050 Povo, Trento; 4Dipartimento di Fisica Università degli Studi di Bologna, v.le Berti Pichat 6/2, 40127 Bologna - 5Dipartimento di Fisica, CNISM, Università degli Studi di Padova, via Marzolo 8 , 35100Padova; 6ESRF, Grenoble (Francia); 7Dipartimento di Fisica ed Ingegneria dei Materiali e Territorio dell’Università Politecnica delle Marche, I-60131 Ancona, Italy
complementary synthesis methods. In particular, Mg-based nanostructured materials (thin films or nanopowders) are prepared by (1) Sputtering techniques, a suitablemethod for the synthesis of model materials where the properties can be easily correlated to the microstructure; (2) inert gas condensation, with the aim to study the finedetails of hydrogen uptake and release in 3D nano-sized model systems and (3) high energy ball milling which represents the main road for industrial scale-up.
[1] N. Bazzanella, R. Checchetto, A. Miotello, C. Sada, P. Mazzoldi, P. Mengucci,
Appl. Phys. Lett., 89, 1 (2006) 014101,
[2] A. Montone, J. Grbovic Novakovic, M. Vittori Antisari, A. Bassetti, E. Bonetti,
A.L.Fiorini, L. Pasquini, L.Mirenghi, P.Rotolo, Int. J. Hydr. Energy, 32, (2007) 2926
[3] A. Bassetti, E. Bonetti, L. Pasquini, A. Montone, J. Grbovic, M. Vittori Antisari, Eur
Phys. J. B, 43 (2005),19
DTA curves of MgH2 in different conditions
SE 1kV
SE 20kV
BSE 20kV
HIGH ENERGY BALL-MILLING:MgH2 with catalysing Fe particles
METALLOGRAPHIC ANALYSIS
FIRST PRINCIPLE CALCULATIONof MgH2 / Mg interface:
MONOSTRUCTURAL
CHARACTERIZATION AND H2 diffusion
MgH2 10h milled
with Fe catalyst
MgH2 10h milled
MgH
2Mg
Mg/MgH
2
As received
MgH2
Effect of
ball milling
Effect
ball milling+
Addiction of
Catalysts
Fe
Lower Temperature!