Theoretical Predictions on Li-Decorated Borophenes as Promising Hydrogen Storage Materials

The experimental realization of two-dimensional borophene provides attractive alternates for hydrogen storage. In this work, we theoretically investigated the metal binding and hydrogen storage performance of the experimentally observed beta(12) and chi(3) borophene by density functional theory (DFT) calculations. The calculation results on adsorption and diffusion of metal adatoms on beta(12) and chi(3) borophene demonstrate that Li possesses the best adsorption performance on the borophenes, and simultaneous binding of two Li on both sides of borophene leads to stronger binding of Li. For the Li decorated borophenes, up to 5 H-2 molecules can be adsorbed around one Li atom, with a moderate average adsorption energy range around 0.40 eV/H-2. The maximum gravimetric density of H-2 can reach 8.76 wt% for Li decorated beta(12) borophene and 10.79 wt% for Li decorated chi(3) borophene. Our researches predicted the great potential of Li decorated beta(12) and chi(3) brophenes as hydrogen storage materials.