Hydrogen generation by aluminum corrosion in cobalt (II) chloride and nickel (II) chloride aqueous solution

Because of its use in on-board hydrogen portable hydrogen-air fuel cell, hydrogen generation based on the reaction between aluminum and water was evaluated. In the present work, the effect of CoCl2 and NiCl2 on aluminum–water reaction was studied. The amount of hydrogen generated linearly increased with increasing NiCl2 concentration from 1 M to 2.5 M, and reached the maximum with 1–1.5 M CoCl2. However, it dramatically decreased with further increase in CoCl2 and NiCl2 concentration. The formation of Co/Al and Ni/Al galvanic cell, the decrease in pH, and the permeation of chloride in the oxide layer supported hydrogen generation. Besides these factors, amorphous Co with higher specific surface area acted as the catalyst to hasten hydrogen generation. The hydrogen evolution in 1 M CoCl2 increased from 30 °C to 45 °C, and then it obviously decreased at 60 °C. The hydrogen generation in NiCl2 showed similar behavior. The by-product Co or Ni could be easily separated by use of a magnetic stirring bar and reused in subsequent rounds of aluminum–water reaction.