Hydrogen storage capacity of C12X12 (X = N, P, and Si)

Nanomaterials have attracted great interest in recent years due to their unique surface properties. The high surface to volume ratio of these materials has significant implications with respect to energy storage. Hydrogen adsorption on modified nanocages: C12N12, C12P12 and C12Si12 are investigated by density functional theory (DFT) calculations at the omega B97X-D/6-311+G (d,p) level of theory. The findings of the surface analysis and the examination of the natural bond orbitals showed that charge transfer occurred throughout the adsorption pro-cess. From the ELF analysis, the electron shared between C12P12 and C12Si12 and the chemical bond formed with the hydrogen molecule infers chemisorption which is consistent with the adsorption energy. C12N12 showed molecular physisorption with an Eads of-0.99 eV, whereas C12P12 and C12Si12 showed chemisorption behavior, the molecular adsorption energy of-2.50 eV was obtained for C12P12 and is observed to be the highest. Therefore, in contrast to other materials, C12P12 is ideal for the storage and adsorption of hydrogen molecules. The negative value for Eads depicts that adsorption of the said molecule is thermodynamically favorable. Furthermore, from the analysis of the NCI the nature of interaction is associated to Vdw and confirms excellent interaction between hydrogen molecule and the adsorbent surfaces.

Automated summary

Nanomaterials with unique surface properties play a significant role in energy storage, and the study suggests that C12P12 is ideal for storing and adsorbing hydrogen molecules with the highest molecular adsorption energy observed among the materials studied.