Investigation on the Hydrogen Production Performance and Hydrolysate Formation Mechanism of Al-Based Composites

Hydrogen production via Al-H2O reaction has potential uses in the fields of space thrusters, engines, and hydrogen fuel cells, where hydrogen production performance of Al-based composites is critical. In this study, low-cost active additives, including g-C3N4 (CN) and NaCl were added to Al–In–Sn (AlIS) alloys by the mechanical ball milling method in order to substitute metal Ga and regulate the hydrogen production activity, as Ga not only increases the cost of Al-based materials but also adversely affects the recycling of products. The results demonstrate that both CN and NaCl additives can effectively enhance hydrogen production performance of AlIS in a single additive system. Further, when 5 wt % of CN and 2.5 wt % of NaCl are concurrently introduced, Al-based composites exhibit the highest hydrogen production efficiency of 94.45% at ambient temperature. The highest hydrogen production rate reaches 475 mL·s–1·gAl–1. Even at 2 °C, there is still 86.66% conversion efficiency. The hydrolysates of the Al-H2O reaction are composed of Al(OH)3 and AlOOH, which are primarily influenced by the reaction temperature and the types of Al-based composites. The hydrolysate formation mechanism is analyzed and proposed.