Nanoconfinement of LiBH4 center dot NH3 towards enhanced hydrogen generation

作者：Li Shaofeng; Sun Weiwei; Tang Ziwei; Guo Yanhui; Yu Xuebin^*

来源：International Journal of Hydrogen Energy, 2012, 37(4): 3328-3337.

DOI：10.1016/j.ijhydene.2011.11.036

• Hydrogen storage
• Ammine lithium borohydride
• Nanoconfinement
• Nanoporous silicon dioxide

Successful synthesis of LiBH4 center dot NH3 confined in nanoporous silicon dioxide (LiBH4 center dot NH3@SiO2) was achieved via a new "ammonia-deliquescence" method, which avoids the involvement of any solvents during the process of synthesis. Compared to the pure LiBH4 center dot NH3, the confined LiBH4 center dot NH3@SiO2 exhibited significantly improved dehydrogenation properties, which not only suppressed the emission of NH3, but also decreased the onset dehydrogenation temperature to 60 degrees C, thus leading to an enhanced conversion of NH3 to H-2. In the temperature range of 60-300 degrees C, the mole ratio of H-2 release for the confined LiBH4 center dot NH3@SiO2 is 85 mol % of the total gas evolved, compared to 2.66 mol % for the pristine LiBH4 center dot NH3. Isothermal dehydrogenation results showed that the LiBH4 center dot NH3@SiO2 is able to release about 1.26, 2.09, and 2.35 equiv. of hydrogen, at 150 degrees C, 200 degrees C, and 250 degrees C, respectively. From analysis of the Fourier transform infrared, Raman, and nuclear magnetic resonance spectra of the confined LiBH4 center dot NH3@SiO2 sample heated to various temperatures, as well as its dehydrogenation product under NH3 atmosphere, it is proposed that the improved dehydrogenation of LiBH4 center dot NH3@SiO2 is mainly attributable to two crucial factors resulting from the nanoconfinement: (1) stabilization of the NH3 in the nanopores of SiO2, and (2) enhanced combination of LiBH4 and NH3 groups, leading to fast dehydrogenation at low temperature.

• 出版日期2012-2
• 单位复旦大学