Elucidation of the Effect of Functional Group Substitution of BN-cyclohexane for Renewable Energy Hydrogen Storage: Density Functional Theory Approach

Liquid organic hydrogen carrier (LOHC) has been attracting attention as a hydrogen storage technology.Among the LOHC materials, we explore fluorine (F) and amine (NH 2 ) functional group substituted 1,2-BN cyclohexane-based hydrogen storage materials with improved reversibility of dehydrogenation-hydrogenation reaction.Density functional theory (DFT) calculations were conducted by using Gaussian 16 software to calculate dehydrogenation reaction enthalpy (∆) and reaction free energy (∆).F-BN-cyclohexane and NH 2 -BN-cyclohexane show ∆ of -4.10 and -5.38 kJ/mol, respectively, whereas 1,2-BN cyclohexane shows ∆ of -5.71 kJ/mol.Because the reversibility of dehydrogenation-hydrogenation reactions is excellent as the ∆ value is close to zero, the functional group substitution enhanced the reversibility of the dehydrogenation-hydrogenation reaction.This DFT study not only presents a systematic methodology to evaluate the dehydrogenation-hydrogenation reaction reversibility that can be improved by substituting F and NH 2 functional groups in existing BN-cyclohexane, but also provides the fundamental mechanisms of dehydrogenation of F-and NH 2 -BN-cyclohexane.