DP Seminar

[Luca Ferialdi]

Department of Physics - University of Trieste

Wednesday 30 March 2011 - 3.00 pm
Room 204 (2nd floor LB)

Dr. Shi-Hao Wei
(Ningbo University)

Title: Hydrogen molecules adsorbed on small transition metal clusters

Abstract:
Light complex hydrides of the type Am(MH4)n (A = Li, Na,Mg; M = Be, B, Al) as potential hydrogen storage materials
have attracted much attention because of their high gravimetric hydrogen densities. However, their poor kinetics and lack
of reversibility of hydrogen absorption/desorption reactions are the most critical problems for practical applications.
The experimental results had indicated that the small size of the Ti clusters plays an important role in increasing the
reaction rate of some of the hydrogen storage materials such as complex metal hydrides.

We perform first principles density functional theory calculations to investigate the geometric and electronic
structures of Tin-mH2 (n=2-7, and m=1-22). By optimizing geometric structures, we obtain the saturated
configurations for hydrogen storage on small Tin (n=2-7) clusters. Interestingly, we find that with an
increase in the size of the Tin cluster, the effective space for each titanium atom to adsorb hydrogen molecules
decreases, as does the maximum amount of hydrogen molecules adsorbed on each titanium atom. When the
size of the Tin cluster goes beyond n=5, the maximum number of hydrogen molecules adsorbed on each Ti
atom keeps a constant of 3. Furthermore, we suggest/propose that the hybridization of atomic orbitals
in different atoms could be used to estimate the type of the
bonds between the different atoms in clusters.