Hydrogen generation using a ball-milled Al/Ni/NaCl mixture

•The amount of hydrogen generated improves with increasing the Ni/Al ratio.•The dissolving of NaCl improves the function of the Al/Ni microgalvanic cell.•The cooperation of Ni, pH and the micro-galvanic cell accelerate hydrogen evolution.•The by-product Ni in NiCl2 is easily separated using magnetic properties. Recently, the aluminum–water reaction has attracted the attention because it is a convenient method for producing on-board hydrogen for a fuel cell. This work is a study of the effect of the Ni/Al ratio, NaCl content and reaction medium on hydrogen generation using the aluminum-water reaction. The induction time is clearly reduced and the hydrogen generation in water is improved by varying the Ni/Al ratio. Increasing NaCl content slightly increases the quantity of hydrogen generated because the dissolving of NaCl in the water enhances its conductivity and also operation of the Al/Ni micro-galvanic cell. Because the pH value of the reaction medium is important for hydrogen evolution, the effects of water, NaOH and NiCl2 on aluminum–water reaction, using the optimal Al/Ni/NaCl mixture, were investigated. It was interesting to discover that synergistic effects of the catalytic function of fresh Ni, the Ni/Al micro-galvanic cell and the decrease of pH value rapidly accelerate the rate of hydrogen production for the Al/Ni/NaCl mixture in NiCl2 aqueous solution. In addition, the byproduct of the aluminum–water reaction in NiCl2 is Ni, which can be readily separated using its magnetic properties.