Comparative study on activation of aluminum with four liquid metals to generate hydrogen in alkaline solution

•Four liquid metals as Al-water reaction catalysts were contrastively investigated.•Ga works as the best than Ga-In, Ga-Sn and Ga-Zn to activate Al-water reaction.•Hydrogen generation allows continuous utilization of liquid metal catalyst.•XRD analysis indicated that liquid metal could be easily separated and reused.

Based on a latest finding on Al-water reaction, we studied the hydrogen production behaviors activated by gallium based liquid metal where the mass percentage of Al was less than 1% in an alkaline environment. Three kinds of room temperature liquid binary alloy including Ga-In, Ga-Sn and Ga-Zn were tested and compared with pure gallium. It was shown that the hydrogen production rate activated by Ga-In alloy was far below than that of pure gallium, while Ga-Sn and Ga-Zn run slightly slower. Aiming to optimize the catalytic performance of pure gallium, we further performed researches to clarify its practical features. We divided five times to add equivalent Al block into pure gallium and found that the rate and quantity of hydrogen production kept unchanged in each batch addition, which suggested that liquid metal as catalyst was activated continuously without impurities mixing to impede catalytic effect. In addition, components analysis of the residual precipitates after reaction with XRD also indicated that there was only Al(OH)3 but no gallium or its derivatives. These findings as clarified by this article can help guide future high performance hydrogen generation and reuse of the liquid metal catalyst.