Electric field improved hydrogen storage of Ca-decorated monolayer MoS2

• Ca binds with MoS2 stalely without clustering.
• It can operate under ambient thermodynamic conditions.
• External electric field can effectively tune the hydrogen adsorption energy.

Hydrogen storage property of Ca-decorated MoS2 is carried out using first-principles calculations. Our calculations demonstrate that the preferential binding of Ca atoms on MoS2 effectively prevent the Ca clustering. Six H2 molecules per Ca atom can be adsorbed with a desirable adsorption energy of 0.14 eV/H2. Both hybridization of the Ca-3d and S-2s with the H-1s orbital and the polarization of the H2 molecules contribute to the hydrogen adsorption. Our results show that the external electric field can effectively tune the hydrogen adsorption energy, therefore making hydrogen storage and release reversible.