Effects of single- and co-substitution of Ti on dehydrogenation of Mg2NiH4: A first-principles study

abstract

• 2015 Elsevier B.V. All rights reserved. Abstract A comparative study of single- and co-substitution of Ti on dehydrogenation of Mg2NiH4 has been carried out from first-principles calculations based on density functional theory. In comparison with Ti single-substitution, the formation enthalpy in co-substituted Mg2NiH4 is higher, showing the lower thermodynamic stability. In Ti co-doped Mg2NiH4, the average NiH bond length of entire unit cell is larger, implying weaker NiH bonds and lower stability of complexes NiH44-. Ti co-substitution further shows a more favorable dehydrogenation effect on Mg2NiH4 due to lower hydrogen dehydrogenation energy, and significantly reduces the dehydrogenation reaction enthalpy of Mg2NiH4 by about 30% compared to the pure state. Further calculated electronic structure demonstrates that the co-substituted Mg2NiH4 displays a metallic behavior with the Fermi level locating at the doping band, and the underlying mechanism for improving dehydrogenation properties of co-substituted Mg2NiH4 can be attributed to the weakened NiH interactions together with the narrowed energy gap.

authors

• Shao, Lin

published proceedings

• Computational Materials Science

author list (cited authors)

• Wei, L., Pan, X., Wu, D., Wang, H., Shao, L., Zheng, J., & Tang, B.

citation count

• 10

complete list of authors

• Wei, Liu-Ting||Pan, Xiong-Ze||Wu, Dong-Hai||Wang, Hai-Chen||Shao, Lin||Zheng, Jie||Tang, Bi-Yu

publication date

• June 2015

publisher

• Elsevier  Publisher

published in

• COMPUTATIONAL MATERIALS SCIENCE  Journal

Digital Object Identifier (DOI)

• 10.1016/j.commatsci.2015.03.009

start page

• 45

end page

• 51

volume

• 103

URL

• http://dx.doi.org/10.1016/j.commatsci.2015.03.009