Hydrogen-deuterium exchange in bulk LiBH4.

Area of Science:

• Solid-state chemistry
• Materials science
• Chemical physics

Background:

• Diffusion of hydrogen in solids is a fundamental process, yet poorly understood in complex hydrides.
• Lithium borohydride (LiBH4) is a promising material for hydrogen storage, necessitating detailed studies of its hydrogen dynamics.

Purpose of the Study:

• To investigate the diffusion mechanisms of hydrogen in LiBH4 using hydrogen-deuterium exchange.
• To quantify the self-diffusion of deuterium in LiBH4.

Main Methods:

• Hydrogen-deuterium exchange experiments were conducted.
• Thermogravimetry and Raman spectroscopy were employed to monitor the exchange process.
• The decomposition of LiBH4 was studied at 523 K.

Main Results:

• Raman spectroscopy indicated a statistical exchange of hydrogen by deuterium in LiBH4.
• The self-diffusion constant of deuterium in LiBH4 was estimated to be approximately 7 x 10(-14) m(2) s(-1) at 523 K.
• The diffusing species was identified as the single hydrogen atom.

Conclusions:

• The study provides crucial insights into the dynamics of hydrogen diffusion in complex hydrides.
• Understanding hydrogen atom diffusion in LiBH4 is vital for optimizing its hydrogen storage capabilities.