A DFT investigation: High-capacity hydrogen storage in metal-decorated doped germanene

Abstract

Germanene is a two-dimensional nanomaterial that has been successfully synthesized and has promising applications in sensing and energy storage. Recent research has focused on exploring the potential of M-decorated (M = K, Ca, and Sc) X-doped (X = B, Al, and Ga) germanene for hydrogen storage. In this theoretical work, a strong binding between K, Ca, and Sc metal atoms and doped germanene is revealed, suggesting that metal atoms adsorbed on doped germanene are energetically stable. Among the systems studied, Sc-decorated boron-doped germanene has a gravimetric hydrogen storage capacity of 5.32 wt%, close to the technical targets of the Department of Energy of the United States. Moreover, a three-atom Sc cluster on boron-doped germanene can adsorb up to 11 hydrogen molecules, with an average adsorption energy of 0.35 eV, desorption temperatures between 285 and 363 K and pressures between 5 and 100 bar. The desorption times are of the order of microseconds under ambient temperature conditions. Sc-decorated Al(Ga)-doped germanene systems could also be suitable for hydrogen storage at slightly increased temperatures or pressures, but K- and Ca-decorated monolayers are not. In summary, these findings demonstrate that Sc-decorated B-doped germanene can be a substrate for practical applications in hydrogen storage.