A quantum study of dihydrogen binding to the lithium alkoxide doped covalent organic framework-105

Abstract

The adsorption properties of multiple hydrogen molecules (1-5 molecules) bound with the COF-OLi structure were predicted by the B3LYP/6-311G(d,p) and ONIOM(B3LYP/6-311G(d,p):AM1) methods. The MP2/6- 311G(d,p) method in conjunction with basis set superposition error (BSSE) was also employed for evaluating adsorption energies of the (H2)n-COF-OLi complexes (n = 1-5). It was found that the ONIOM(B3LYP/6- 311G(d,p):AM1) level of theory appropriates to characterize hydrogen adsorptions on the COF-OLi structure. The adsorption energy of the H2-COF-OLi complex obtained from the MP2/6-311G(d,p) method including BSSE correction is ?2:51 kcal/mol, while corresponding energy of ?4:27 kcal/mol was evaluated for two molecules of hydrogen. In the case of three hydrogen molecules, the adsorption energy of ?5:61 kcal/mol is obtained, which is weaker than that of ?6:37 kcal/mol calculated from the (4H 2)-COF-COF-OLi complex. Finally, the strongest adsorption energy of ?7:12 kcal/mol was predicted for five hydrogen molecules. © 2012 The Surface Science Society of Japan.