Ti deposited C20 and Si20 fullerenes for hydrogen storage application, DFT study

Abstract

In this work, Ti deposited C20, Si20, and KSi20 as hydrogen storage materials have been studied utilizing the DFT (B3LYP and M06-2X)/6-311 g (d,p). The encapsulated K atom in the Si20 cluster provides the fullerene regular shape to the KSi20 cluster. The Ti atom tends to bind with two adjacent C or Si atoms. The Ti@Si20 can absorb up to five hydrogen molecules while Ti@C20 and Ti@KSi20 can adsorb more than five hydrogen molecules. The calculated enthalpy difference emphasizes the physisorption of hydrogen on the investigated clusters for a number of hydrogen molecules greater than one. For a wide range number of hydrogen molecules (n ¼ 1e6) for the nH2/Ti@KSi20, the adsorption energy per hydrogen molecule (Eads) values satisfy the United States Department of Energy (DOE) target for hydrogen storage materials while for nH2/Ti@C20 and nH2/Ti@Si20 the target is satisfied for n ¼ 3e6 and n ¼ 4e5, respectively. This means that the small-stabilized KSi20 fullerene may be a candidate material for hydrogen storage applications.