Trapping of hydrogen atoms inside small beryllium clusters and their ions

Highlights: • Core-shell systems of small beryllium cages doped by atomic hydrogen are studied. • Their geometries are selectively sensitive to the H-doping and the charge state. • The energy barrier to hydrogen exit changes significantly in the ions. • Assemblies of such clusters show potential for charge-controlled hydrogen release. Structure, stability and electronic properties are evaluated computationally for small Be_n (n = 5–9) cluster cages accommodating atomic H inside and forming core-shell species. These parameters are predicted to vary significantly upon insertion of H, for ionic derivatives, and with the system size. In particular, the energy barrier for H-atom exit from the cage changes significantly for ions compared to the neutral counterparts. The corresponding effects predicted for cage assemblies suggest the possibility of efficient charge-control of hydrogen release. This, together with a high capacity for storing hydrogen in extended such assemblies might indicate a possible way towards feasible hydrogen-storage solutions.