Hydrogen adsorption on pristine, defected, and 3d-block transition metal-doped penta-graphene

The effects of different crystallographic defects and substitutional doping of 3d-block transition metals (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn) on the electronic properties and hydrogen molecule (H2) interaction of penta-graphene (PG) were investigated using density functional theory calculations. Electronic properties of PG show strong dependence on PG's structural configuration and the type of metal dopants used. Doping PG with transition metals (TM) may be used to change PG from being a wide band gap semiconductor to a narrow band gap semiconductor or a semimetal. PG have H2 adsorption energies (Eads) that are superior to graphene, with Eads between −0.7 eV and −0.9 eV depending on the adsorption site. Transition metals act as proton rich dopant, and induced positive electrostatic potential in its adjacent regions. Thus, doping improve H-2 adsorption, especially when substituted on sp2 hybridized carbon site. The V-doped and Ti-doped sheets, with Eads of −0.351 eV and −0.319 eV, respectively, show the greatest potential for on-board reversible solid-state hydrogen molecule storage application.