Synergistic effect of the fresh Co, Ni, and anion ions on aluminum or magnesium with water reactions

To analyze the effect of Co and Ni on hydrogen generation in water, the reactions of Mg and Al with water in CoCl2 and NiCl2 solutions are studied in terms of amount of H2 produced and rate of reaction. Mg rapidly reacts with water in CoCl2 and NiCl2, producing high amount of H2 without induction time. While there is a short induction time is detected for Al─H2O reaction in CoCl2 and NiCl2. In addition to the galvanic cell behavior of the Mg (Al)/Co (Ni) compounds formed, Co and Ni catalyze the hydrogen production reaction; however, the agglomeration of Co or Ni leads to a noticeable decrease in H2 production. The open-circuit potential in CoCl2 and NiCl2 solutions after the addition of Mg or Al at ambient temperature shows an obvious change, coinciding with the initiation of the hydrogen generation process. Mg rapidly reacts with water in Co (Ac)2, CoSO4, Ni (Ac)2 and NiSO4 solutions as a consequence of its intrinsic metallic properties and of the formation of Co or Ni. The hydrogen production amount is lower (<200 ml g−1) in Co (NO3)2 and Ni (NO3)2, even after adding NaCl. No reaction occurs when adding Al in CoSO4, Co (Ac)2, Co (NO3)2, NiSO4, Ni (Ac)2, and Ni (NO3)2. The synergistic effect of Co, Ni, and anion ions in water affects the rate of Al or Mg corrosion and hydrogen generation.