First-principles study on impact of Mo doping on the formation enthalpy and electronic structure of Li2MgN2H2 material

Abstract

The influence of Mo doping on the formation enthalpy and electronic structure of Li₂MgN₂H₂ material, as well as the specific improvement mechanism of its hydrogen storage properties, were investigated by employing the first-principles calculation method. The calculation results exhibit that when Mo is doped into the Li₂MgN₂H₂ material, it is more inclined to take up Mg lattice site at the 8c position. For the Li₂MgN₂H₂ material, Mo doping can effectively reduce its formation enthalpy by ca. 91.16 kJ/mol, thus resulting in the reduction of its structural stability. Moreover, when the Li₂MgN₂H₂ material is doped with Mo, its cell volume increases, and its band gap narrows obviously. Meanwhile, the strong force between Mo and N causes the bond strengths of N–H and Li–N to weaken significantly. The aforementioned factors are beneficial to the improvement of its hydrogen sorption kinetics. This work aims to provide theoretical guidance for further development of new efficient catalysts to promote the Li–Mg–N–H material's application.