TY - JOUR
T1 - Role of Metal Electronegativity in the Dehydrogenation Thermodynamics and Kinetics of Composite Metal Borohydride-LiNH2 Hydrogen Storage Materials
AU - Bai, Ying
AU - Pei, Ziwei
AU - Wu, Feng
AU - Wu, Chuan
N1 - Publisher Copyright:
© 2018 American Chemical Society.
PY - 2018/3/21
Y1 - 2018/3/21
N2 - The composites of M(BH4)n-LiNH2 (1/2n molar ratio, n = 1 or 2, M = Ca, Mg, Li) were synthesized by liquid ball milling. Samples were characterized by X-ray diffraction, thermogravimetry-differential thermal analysis-mass spectroscopy (TG-DTA-MS), and kinetic models (Achar differential/Coats-Redfern integral method). The higher-electronegativity metal M in M(BH4)n-4LiNH2 (M = Ca, Mg) samples not only enables [BH4]- group to release easily, so as to facilitate the interaction of [BH4]- and [NH2]- groups, but also restrains the NH3 release and slightly decreases the onset dehydrogenation temperature concluded by TG-MS. Moreover, in stage 1 (200-350 °C), the kinetics performances of M(BH4)n-4LiNH2 (M = Ca, Mg) samples are distinctly improved, that is, the activation energies of them are reduced by ca. 30% compared to those of sample LiBH4-2LiNH2. The outstanding contribution of the replacement of M(BH4)n with high-electronegativity metal ion is to both improve the kinetics performance by changing the kinetics mechanism and decrease the temperature range of the initial dehydrogenation region.
AB - The composites of M(BH4)n-LiNH2 (1/2n molar ratio, n = 1 or 2, M = Ca, Mg, Li) were synthesized by liquid ball milling. Samples were characterized by X-ray diffraction, thermogravimetry-differential thermal analysis-mass spectroscopy (TG-DTA-MS), and kinetic models (Achar differential/Coats-Redfern integral method). The higher-electronegativity metal M in M(BH4)n-4LiNH2 (M = Ca, Mg) samples not only enables [BH4]- group to release easily, so as to facilitate the interaction of [BH4]- and [NH2]- groups, but also restrains the NH3 release and slightly decreases the onset dehydrogenation temperature concluded by TG-MS. Moreover, in stage 1 (200-350 °C), the kinetics performances of M(BH4)n-4LiNH2 (M = Ca, Mg) samples are distinctly improved, that is, the activation energies of them are reduced by ca. 30% compared to those of sample LiBH4-2LiNH2. The outstanding contribution of the replacement of M(BH4)n with high-electronegativity metal ion is to both improve the kinetics performance by changing the kinetics mechanism and decrease the temperature range of the initial dehydrogenation region.
KW - activation energy
KW - ball milling
KW - dehydrogenation
KW - electronegativity
KW - kinetics mechanism
UR - http://www.scopus.com/inward/record.url?scp=85044292288&partnerID=8YFLogxK
U2 - 10.1021/acsami.8b01529
DO - 10.1021/acsami.8b01529
M3 - Article
C2 - 29469569
AN - SCOPUS:85044292288
SN - 1944-8244
VL - 10
SP - 9514
EP - 9521
JO - ACS applied materials & interfaces
JF - ACS applied materials & interfaces
IS - 11
ER -