Ab-initio investigation of hydrogen sorption in Ti functionalized modified calix[4]pyrrole-benzene

Abstract

Hydrogen is an ecofriendly and affordable alternative for fossil fuels. Storage of hydrogen with high hydrogen weight percentage is the prime obstacle to use it as a fuel. The hydrogen storage capacity in Ti functionalized modified calix[4]pyrrole-benzene is explored using density functional theory. Hydrogens are sequentially adsorbed over functionalized Ti atoms as well as over the p complexes of acetylenic linkages and pyrrole rings. The host stores 28 H2 with a maximum H wt% of 10.1 and sorption energies in the range of 0.50e0.25 eV. Mechanism of the quasi-molecular adsorption is explained through the analyses of electrostatic potential, distance parameters, and charges. Findings of molecular dynamics, van ‘t Hoff desorption analysis, and the occupation number prove that the host is thermally stable and stores H2 reversibly. Ti functionalized modified calix[4] pyrrole-benzene proves to be a potential hydrogen storage candidate fulfilling the 2020 targets set by the US, DOE.