The properties of hydrogenated derivatives of the alkali atom coated clusters C6M6 (MÂ =Â Li, Na): A density functional study

It can be known from the figure that the reactive points of C6Li6 mainly distribute on six Li atoms, whereas the reactivity points of C6Na6 mainly locate on six C atoms. Therefore, C6Li6 should have better hydrogen storage ability than that of C6Na6. The calculated Ec explores that each Li of C6Li6 can most adsorb four H2 molecules, while each Na of C6Na6 can only adsorb two H2 molecules. The calculated hydrogen storage density of C6(Li-4H2)6 is 29.60 wt%, much larger than that of C6(Na-2H2)6 (10.26 wt%), however, they both are much higher than the 5.5 wt% target at 2017 proposed by the U.S. department of energy (DOE).