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

Summary To analyze the effect of Co and Ni on hydrogen generation in water, the reactions of Mg and Al with water in CoCl 2 and NiCl 2 solutions are studied in terms of amount of H 2 produced and rate of reaction. Mg rapidly reacts with water in CoCl 2 and NiCl 2 , producing high amount of H 2 without induction time. While there is a short induction time is detected for Al─H 2 O reaction in CoCl 2 and NiCl 2 . 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 H 2 production. The open-circuit potential in CoCl 2 and NiCl 2 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 , CoSO 4 , Ni (Ac) 2 and NiSO 4 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 (NO 3 ) 2 and Ni (NO 3 ) 2 , even after adding NaCl. No reaction occurs when adding Al in CoSO 4 , Co (Ac) 2 , Co (NO 3 ) 2 , NiSO 4 , Ni (Ac) 2 , and Ni (NO 3 ) 2 . The synergistic effect of Co, Ni, and anion ions in water affects the rate of Al or Mg corrosion and hydrogen generation.