First-principles study of Pd single-atom catalysis to hydrogen desorption reactions on MgH2(110) surface

MgH2 is a promising and popular hydrogen storage material. In this work, the hydrogen desorption reactions of a single Pd atom adsorbed MgH2(110) surface are investigated by using first-principles density functional theory calculations. We find that a single Pd atom adsorbed on the MgH2(110) surface can significantly lower the energy barrier of the hydrogen desorption reactions from 1.802 eV for pure MgH2(110) surface to 1.154 eV for Pd adsorbed MgH2(110) surface, indicating a strong Pd single-atom catalytic effect on the hydrogen desorption reactions. Furthermore, the Pd single-atom catalysis significantly reduces the hydrogen desorption temperature from 573 K to 367 K, which makes the hydrogen desorption reactions occur more easily and quickly on the MgH2(110) surface. We also discuss the microscopic process of the hydrogen desorption reactions through the reverse process of hydrogen spillover mechanism on the MgH2(110) surface. This study shows that Pd/MgH2 thin films can be used as good hydrogen storage materials in future experiments.