A Novel Method for Generating H2 by Activation of the μAl-Water System Using Aluminum Nanoparticles

A method is described for activation of the reaction of room temperature water with micron-scale aluminum particles (μAl) by the addition of poly(epoxyhexane)-capped aluminum nanoparticles (Al NPs). By themselves, Al NPs react vigorously and completely with water at ambient temperatures to produce H2. While pure μAl particles are unreactive toward water, mixtures of the μAl particles comprising 10 to 90% (by mass) of Al NPs, demonstrated appreciable hydrolytic activation. This activation is attributed to the reaction of the Al NPs present with water to produce a basic solution. Speciation modelling, pH studies, and powder X-ray diffraction analysis of the hydrolysis product confirm that the pH change is the key driver for the activation of μAl rather than residual heat from the exothermicity of Al NP hydrolysis. A mechanism is proposed by which the nonreactive aluminum oxide layer of the μAl is eroded under basic conditions. Mixtures 10% by mass of Al NPs can be used to produce the optimal quantity of H2.