Ca-decorated borophene as potential candidates for hydrogen storage: A first-principle study

Based on density functional theory calculation, we have investigated the hydrogen storage properties of three types of Ca-decorated borophene which have been recently synthesized experimentally. It is found that Ca atoms have strong bonding strength with borophene without the problem of aggregation. The configuration of borophene has an important effect on the H₂ storage capacity. Ca-decorated borophene of S2 and S3 are promising materials system for high-capacity hydrogen storage with gravimetric hydrogen density 9.5 wt% and 7.2 wt% while that of S1 are not. Not only the polarization mechanism but also the orbital hybridization are involved in the adsorption of H₂. The temperature and pressure have also been taken into consideration. All the hydrogen adsorbed structures of S2 and S3 are stable at room temperature under mild pressure. Our results indicate that Ca-decorated borophene of S2 and S3 structures could be expected to be promising H₂ storage materials for H₂ fuel battery.