Boron substitution effect on adsorption of H2 molecules on organometallic complexes

Abstract Hydrogen adsorption properties of Be/Sc doped pentalene complexes are investigated using second ordered Moller-Plesset method (MP2). In order to study the boron substitution effect, pentalene is further modified by substituting two and four boron atoms for carbon atoms at different positions and named as TBP1 and TBP2 for two boron atom substituted structures and FBP1 and FBP2 for four boron atom substituted structures. Two H 2 molecules get adsorbed on each Be doped complex and having 3.25, 3.31, 3.31, 3.38 and 3.38 wt% H 2 uptake capacity for C 8 H 6 Be 2 , TBP1Be 2 , TBP2Be 2 , FBP1Be 2 and FBP2Be 2 complexes respectively. All Sc doped pentalene and boron substituted pentalene complexes can interact with nine H 2 molecules except TBP2Sc 2 complex. The TBP2Sc 2 complex can adsorb eight H 2 molecules. The H 2 uptake capacity is found to be 8.63, 8.73, 7.84, 8.83 and 8.83 wt% for C 8 H 6 Sc 2 , TBP1Sc 2 , TBP2Sc 2 , FBP1Sc 2 and FBP2Sc 2 complexes respectively. Gibbs free energy corrected adsorption energy plots show that the H 2 adsorption on all Be doped complexes is possible at all temperatures and pressures considered here. The TBP1Sc 2 complex seems to be more promising hydrogen storage material among all Sc doped complexes over a wide range of temperature and pressure. The H 2 desorption temperatures obtained for the Be doped complexes are higher than the Sc doped complexes. Stability of the complexes is predicted with the help of the gap between the highest occupied molecular orbitals and the lowest unoccupied molecular orbitals.