The high hydrogen storage capacities of Li-decorated borophene

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In this work, we calculate stabilities, electronic properties and hydrogen adsorption properties of Li-decorated freestanding borophene. It was studied through three functionals (vDW, LDA and PBE) of the first principles density functional theory (DFT) methods. It was found that the adsorption energy ofH2 on the pure borophene was small. The Li atoms decoration can improve the H2adsorption capacity. By virtue of the larger binding energy than that for bulk Li, Li atoms can be adsorbed steadily and not form the clusters on the 2×2 borophene supercell surface. For single Li atom adsorbed, the maximum number ofuptake is three hydrogen molecules. But for Li adsorbed on both sides of borophene, each Li atom can absorb up to four H2 molecules. Its hydrogen storage capacity reaches up to 13.7wt% with an average adsorption energy of 0.142 and 0.176eV/H2 for vDW and LDA functional without the consideration of temperature, respectively.At the room temperature, the hydrogen capacity is up to 9.1wt%. This study suggests that Li-decorated borophene is a potential hydrogen storage medium.