Study on the hydrogen generation performance and hydrolyzates of active aluminum composites

In this paper, aluminum (Al) composites with low melting point metal bismuth (Bi) and bismuth oxide (Bi2O3) are prepared to realize great hydrogen generation capacity by the ball milling method. The hydrogen generation of Al–Bi composite reacts with water (the initial temperature is 35 °C) can reach 1120 mL/g. The Al–Bi–Bi2O3 produces 1140 mL hydrogen within 2 min by simply raising the initial water temperature to 55 °C. The hydrolyzates of the Al composites are collected and characterized. It indicates that the hydrolyzate of Al–Bi composite mainly includes AlOOH (boehmite), while for the Al–Bi2O3 the hydrolyzate is Al(OH)3 (gibbsite). The scanning electron microscope (SEM) images suggest that the AlOOH particles have more pores than Al(OH)3 particles, which benefit for hydrogen escaping from the hydrolyzate particles surface and for inner Al contacting with water. The Al(OH)3 particles easily accumulate and form a dense layer on the surface of Al particles, which inhibits the hydrogen generation.