First-principles study of hydrogen storage in metal functionalized [4,4]paracyclophane

Abstract

Storing hydrogen for commercial purpose with high gravimetric density is a major task. Li and Sc are functionalized over delocalized π electrons of [4,4]paracyclophane to explore reversible hydrogen storing capacity. Electronic structure calculations are performed with Minnesota 06 hybrid functional and 6-311G(d,p) basis set. [4,4]paracyclophane binds strongly to Sc showing Dewar coordination. Sc functionalized [4,4]paracyclophane complex has a capacity of holding 10 H2 molecules while Li functionalized complex holds 8 H2 molecules with hydrogen weight percentage of 11.8% and 13.7% respectively. Conceptual DFT parameters namely hardness and electrophilicity confirm the high stability of the complexes. Atom Density Matrix Propagation simulations at various temperatures and their desorption pattern indicate reversibility of adsorbed hydrogens. The study confirms the potential of Sc functionalized [4,4]paracyclophanes as a hydrogen storage material.