Rapid hydrogen generation from the reaction of aluminum/activated charcoal composite with alkaline solution

Abstract

Formation of surface passivation layer is a major problem that restricts the potential of aluminum (Al)-H2O system for hydrogen source applications. Several reaction-promoting approaches have been developed, but most of them are costly. Herein, we report a simple yet highly effective method for improving the reactivity of Al with alkaline solution. Our study found that mechanically milling Al powder with the cheap and readily available activated charcoal (AC) for short periods of time could significantly improve the hydrogen generation kinetics of Al-H2O system, to a level far exceeding that of the systems with oxide or salt promoters. For instance, the 15 min-milled Al/AC composite with a mass ratio of 5:1 could fulfill a 98% fuel conversion within ∼1 min in a 1 M NaOH solution, and its maximal hydrogen generation rate reached up to 4556 mL min−1 g−1, which was over 18-fold faster than that of Al powder. A favorable combination of low material cost, simple preparation process and fairly good H2 generation performance makes the thus-constituted Al/AC-H2O system promising for mobile and portable applications. The promoting effect of AC additive on Al-H2O reaction kinetics was discussed based on the microstructure characterization and control experiments.