Study of hydrogen adsorption by N+- and Si-decorated sumanene

Abstract

The bowl-shaped π-conjugated sumanene has been found to give an appreciable capacity in the field of hydrogen storage. In the present paper, two series of substituted sumanene have been studied at MP2/6-311++G(d,p)//b3lyp/6-31++G(d) level of theory. The substitution involved small and large atoms, namely silicon and charged nitrogen, at different positions in the sumanene molecule. The concave side of the buckybowl has been chosen to study the interaction with hydrogen. The calculated binding energies have been corrected with basis set superposition error (BSSE) and with zero-point energy (ZPE). Beside structural properties and thermochemistry, natural population analysis charges and natural bond orbital analysis have been elucidated. Results showed an influence of substitution site and atom size on binding energies, through a comparison with pristine sumanene. For one hydrogen molecule per unit cell, the gravitation storage capacity of nitrogen- and silicium-substituted sumanene has revealed 0.74 wt% and 0.71 wt%, respectively. This theoretical study attempts to give a new insight into the field of hydrogen storage by classifying the eligible candidates.