Water formation on oxygen exposure of some hydrides of intermetallic compounds

It is found that a large number of metal hydrides such as hydrides of materials in Ca−Mg−Ni can form water when exposed to O₂ largely without signs for concomitant substrate oxidation. One can speak of a catalytic reaction in this connection as the H-depleted metal matrix can in most cases be rehydrided and water synthesis repeated on exposure to O₂. In some cases a considerable portion of the H combustion reaction takes place in a matter of seconds. Some of the metal hydrides such as hydrides of CaNi₄B, CeNi₃, and YbNi₂, are relatively stable concerning decomposition of the alloy by the product water, while others, for example hydrides of CaNi₃, and CaNi₂, are rapidly decomposed by the product water forming the hydroxide of the electropositive metal. They also produce fine ferromagnetic Ni-particles which could be interesting for other catalytic purposes. Guest professor, work also performed at University of California at San Diego where support by a grant from DOE, Basic Energy Sciences, is acknowledged.