Synthesis and Characterization of New Complex Borohydrides for Hydrogen Storage

摘要

Mechanochemical synthesis has been employed to prepare new light weight complex borohydrides, Zn(BH_4)_2. The thermal calorimetric and gravimetric analysis of these complex borohydrides shows the hydrogen decomposition temperature (T_(dec)) of about 100℃ with theoretical capacity of ～8.0 wt%. This advanced materials based technology is considered to be suitable for attaining the US-DOE grand challenge technical targets. The powder x-ray diffraction analysis of the mechanically milled Zn(BH_4)_2 exhibits the presence of zinc borate and NaCl phase. The FTIR spectra of BH_4~- ion in NaBH_4 has a characteristic band at 2290 cm~(-1), whereas in Zn(BH_4)_2, it occurs at ～2061 cm~(-1) (bridging B-H bonds) and ～2451 cm~(-1) (terminal B-H bonds) as well. The reversibility of hydrogen decomposition and recombination process is carried out by PCT measurements with multi-cycling procedure.