Synthesis of amorphous manganese borohydride in the (NaBH 4 –MnCl 2 ) system, its hydrogen generation properties and crystalline transformation during solvent extraction

The Effects of Additives on the Dehydrogenation of Amorphous Manganese Borohydride and Its Crystalline Form after Solvent Filtration/Extraction

“…% Ni) samples, respectively. A refinement of the initial powder mixture with some pronounced agglomerations can be seen, in comparison with the large-size of the as-received NaBH 4 and MnCl 2 particulates, already shown by Varin et al [11]. However, it appears from Figure 1c that the entangled filamentary Ni morphology is preserved during ball milling to an extent, and does not disperse into individual, smaller particles of Ni as expected.…”

“…% up to 200 • C, for which a DSC curve also showed an endothermic event. In addition, this second sample exhibited a very similar MS pattern (an MS plot not included here) to that in Figure 3a, having the MS peak intensity ratio H 2 /B 2 H 6 = 1256, again, much higher than that reported for the additive-free material [11]. corresponds to H2 within the range from ~100 to 200 °C (a maximum at ~160 °C), which is accompanied by a very small peak of diborane (B2H6) that commences at ~135 °C and terminates at ~180 °C, with a peak maximum at ~160 °C.…”

“…These are accompanied by the discernible Ni peaks in this particular sample. Apparently, a mechanochemical reaction occurred between the NaBH 4 and MnCl 2 reactants during ball milling, which produced a NaCl-type salt accompanied by an amorphous a-Mn(BH 4 ) 2 -type hydride, as reported by Varin et al [11]. This issue will be discussed in more detail later.…”

“…However, plate-like graphene powder particles are rather well dispersed (Figure 1b). The SEM micrographs for the as-received NaBH 4 and MnCl 2 primary reactants were reported by Varin et al [11] and are not shown here. Suffice it to say that both primary reactants are very coarse, with a globular morphology [11].…”

“…corresponds to H2 within the range from ~100 to 200 °C (a maximum at ~160 °C), which is accompanied by a very small peak of diborane (B2H6) that commences at ~135 °C and terminates at ~180 °C, with a peak maximum at ~160 °C. The intensity ratio of the MS H2/B2H6 signal up to 200 °C (the threshold temperature for the end of the B2H6 release) equals 1844, which can be compared to the ratio of 948 for the additive-free 0.5 h BM (2NaBH4 + MnCl2) sample that was investigated by Varin et al [11]. This shows that the quantity of B2H6 released up to ~200 °C, from the sample with graphene, is smaller than that released from an additive-free sample.…”