Stability and hydrogen storage properties of various metal-decorated benzene complexes

Stability and hydrogen storage properties of various metal-decorated benzene complexes have been studied using a first-principles method. According to our results, most metals from the first to the third period of the periodic table can be strongly adsorbed on the benzene surfaces, except Be, Na, Mg, K, and Zn. Among the metals we studied Ca is the most promising adsorbate for hydrogen storage. Two Ca atoms prefer to be isolated on the benzene surfaces, one on each side, and each adsorbed Ca can adsorb up to four H2 molecules, thus yielding a H2 uptake of 9.2 wt%. The calculated binding energy is 0.45 eV/H2, suitable for reversible hydrogen storage. The adsorbed Li and Sc can also adsorb a large number of H2 molecules with suitable H2 binding energies, but they are likely to dimerize on the benzene surfaces. Other metal adsorbates we studied are not suitable for hydrogen storage, because they will suffer from the large H2 binding energy or the low hydrogen storage capacity.

► Binding properties of eighteen metals to benzene are investigated.
► Hydrogen storage properties of various metal-benzene complexes are investigated.
► Ca is found to be the most promising adsorbate for hydrogen storage.
► Li and Sc are also promising adsorbates for hydrogen storage.
► Most of the studied metals are likely to dimerize on benzene surfaces.