Theoretical investigations of the interaction between transition-metal and benzoquinone: Metal dispersion and hydrogen storage

Abstract The dispersion of transition metals (TM) has been an ongoing challenge for quasi-molecular H 2 storage. Here we have investigated the adsorption of TM (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn) on benzoquinone (BQ), by using the first-principles methods. It is found that Sc or Ti (Sc/Ti) atom is energetically favored to bind with ortho-BQ (OBQ) to form OBQ–Sc/Ti complex when compared to their bulk structures. Notably, the coordination number of Sc/Ti is only two, thereby providing enough empty d orbitals for H 2 storage without geometrical blocking. Four H 2 molecules can be accommodated by each OBQ–Sc complex via Kubas-like interaction, with the adsorption energy of 0.20 eV/H 2 and the H 2 storage capacity of ∼5.0 wt%. For practical application, two types of structures have been proposed for H 2 storage using BQ molecule as building block, which would guarantee the dispersing of Sc atom and avoid clustering of OBQ–Sc complexes. In particular, for Sc-decorated oxygen-terminated zigzag graphene nanoribbons, the capacity of H 2 storage reaches up to 6.0 wt%.