Novel Ti-decorated borophene χ3 as potential high-performance for hydrogen storage medium

Recently, an eye-catching boron monoatomic layer named χ3 has been synthesized in lab and subsequent studies have confirmed its high stability. As a novel borophene, the theoretical explorations prior to the experiments are crucial for its applications. In the present work, we perform systematically theoretical calculations on this new synthesized layer for the capacity of hydrogen storage. By decorating the nanosheet with Ti atoms, the hydrogen storage capacity is dramatically enhanced, and Ti atoms tend to be dispersed on the borophene χ3, since an energy barrier larger than 1.15 eV prevents the aggregation of Ti atoms. Ultimately, up to eight hydrogen molecules are stably bound to each Ti atom in B16Ti4 (Ti atoms decorated two-side of 2 × 2 borophene χ3 supercell) with an average adsorption energy of 0.199 eV/H2, corresponding to the highest capacity of hydrogen storage with a gravimetric density of 15.065 wt%. The charge transfer in B16Ti4 introduces a built-in electric field and leads to the polarization of H2 molecules, consequently enhances the hydrogen storage capacity of χ3.