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.