"Nanotechnology and nanomaterials"

Nanocomposites based on metal borohydrides 
for reversible hydrogen sorption
Saldan I.
Department of Physical and Colloid Chemistry, Ivan Franko National University of Lviv. Kyryla and Mefodia St. 6, 79005-Lviv, Ukraine
E-mail: saldanivan@gmail.com

It is useful to make a distinction between hydrogen physical (H-H bond in the gas phase is preserved in the adsorbed state) and chemical sorption (H-H bond is broken during the sorption process). Also chemisorption may occur only in a monolayer on a surface, whereas physisorption is usually accompanied by multilayer adsorption depending upon the temperature. Therefore, description of atomic hydrogen chemical sorption becomes dissimilar to molecular hydrogen physical sorption [1]. In contrast to the traditional metal hydrides, in which hydrogen storage involves the reversible hydrogen entering/exiting of the host hydride lattice, LiBH4 release hydrogen via decomposition that produces segregated LiH and amorphous boron. This is obviously the reason why lithium borohydride applications in fuel cell meet so far only one requirement – high hydrogen storage capacity [2]. Among all known borohydrides, magnesium borohydride is the only one that demonstrates a partial reversible hydrogen sorption in moderate conditions [3]. 
The review summarizes the main challenges still present for metal borohydride that are decomposition and formation providing hydrogen mobility to be used as hydrogen storage material. Modern technological approaches, including nanoconfinement and nanocatalysis, to develop nanocomposites based on metal borohydride are considered and discussed in details.

1.	Saldan I. Thermodynamics of hydrogen gas–solid reaction // Proceedings of the Shevchenko Scientific Society. Chem. Sci.-2014.-40.-P. 106-115.
2.	Saldan I. A prospect for LiBH4 as on-board hydrogen storage // Centr. Euro. J. Chem.-2011.-9.-P. 761-775.
3.	Saldan I. Decomposition and formation of magnesium borohydride // Int. J. Hydrogen Energy.-2016.-41.-P. 11201-11224.