First-principles insights into influencing mechanisms of metalloid B on Mg-based hydrides

First-principle calculations were carried out to provide insights into the improved dehydrogenation performance of B-doped Mg-based metal hydrides in this work. Through the analysis of the crystal structure, dehydrogenation kinetics and thermodynamics, it was found that both of the kinetic and thermodynamic properties are improved by interstitially doping metalloid B into Mg-based alloys. The relative formation enthalpies of Mg-B-based alloys and their hydrides could reach up to 0.508 and 0.303 eV·atom⁻¹, respectively, on account of the mutual interactions between B and Mg atoms. The dehydrogenation energy and desorption temperature of Mg-B-based hydrides could be reduced respectively by up to 32.2% and 166 °C, due to the weakening of the bonding effects between Ni and H atoms caused by the hybridization of B s, B p and H s orbitals. Moreover, the Mg-B-based hydrides with the moderate desorption temperature of 75 °C are suitable for most practical applications.