Influences of Al, Ti and Nb doping on the structure and hydrogen storage property of Mg(BH4)2(001) surface – A theoretical study

• In Mg(BH4)2(001) surface, substitution of Mg with Ti is easier than with Al and Nb.
• Ti and Nb substitutions facilitate H dissociation in Mg(BH4)2(001) surface.
• Ti and Nb substitutions reduce the energy barrier and do favour H diffusion.

First-principles calculations were performed to investigate the influences of Al, Ti and Nb doping on the structure, the hydrogen dissociation energy, the electronic structure and the diffusion path of H atom in Mg(BH4)2(001) surface. The calculated occupation energies indicate that substitution of Mg atom with Ti is the easiest, with Al is a little harder, and with Nb is the most difficult. The doping can reduce the strengths of B–H bonds around the dopants thus favours the dissociation of these H atoms. In comparison, the Nb doping shows the most outstanding effect and the Al doping has the least influence on the dissociation of hydrogen atoms. The minimum energy pathways (MEP) calculations indicate that the substitutions with Ti and Nb can reduce the energy barriers of hydrogen diffusion and thus facilitate H diffusion in the Mg(BH4)2(001) surface, whereas the substitution with Al is not an effective technique for improving the hydrogenation/dehydrogenation performance of Mg(BH4)2.

The substitutions of Ti and Nb for Mg can favour the hydrogen dissociation and facilitate the hydrogen diffusion in Mg(BH4)2(001) surface, whereas Al substitution is not an effective technique.Figure optionsDownload as PowerPoint slide