Simulation of nanosizing effects in the decomposition of Ca(BH4)2 through atomistic thin film models

In this work, we model thin films of β-Ca(BH4)2 to understand how nanostructuration of the material can be an effective way to decrease the dehydrogenation enthalpy. Two different crystallographic faces of Ca(BH4)2 have been investigated (i.e., (001) and (101)), and two reaction pathways have been considered that release hydrogen through the formation of CaH2 and CaB6, respectively. Quantum mechanical calculations predict that size reduction from bulk to nanoscale leads to a sizeable decrease of the decomposition enthalpy of the borohydride of about 5 kJ/molH2. Therefore, the present results corroborate the evidence that nanostructured metal borohydrides show advantages for energy storage applications compared to their bulk counterparts.