Interaction of Ga-In Eutectics with Commercial Aluminum Alloys. Formation of Nanoctructured Material for Hydrogen Cartridges
The use of aluminum and its alloys to produce hydrogen from water has been actively discussed for a long time . A special term "aluminous hydrogen energy" was even formed . Recent interest in such work has been growing with the use of aluminum as a material for hydrogen cartridges. The hydrogen produced in this way does not contain impurities and can be directly used in compact fuel cells without further purification . There are three main areas of research related to the production of hydrogen in the reaction of aluminum with water. The first is the reaction of aluminum powders with water in an alkaline medium. The second is the use of specially prepared aluminum alloys. The third is an increase in the reactivity of aluminum by means of various activating treatments. The principal difference of this work is the use of commercial aluminum alloys as a starting material, which underwent special activating treatment by interaction with a Ga-In eutectic alloy (25 wt% In, 75 wt% Ga) with Tmelt. = 15.9 °C).
With the help of a large complex of physical methods of investigation, such as SEM, EDX, XPS, XRD, EXAFS, X-ray tomography by SR, it was shown that the activated product with high reactivity is a nanostructured material in which the components of the Ga-In eutectic are distributed on the grain boundaries in the entire mass of the original commercial alloy. It is of fundamental importance that gallium and indium are in a metallic state, and their oxidation leads to deactivation of the product. The reactivity of the activated material essentially depends on the morphology of the original commercial alloy. The necessary amount of the activator also depends on the morphology of the initial alloy.
In this work, to intensify the penetration of Ga-In along the grain boundaries, the activation was performed in an ultrasonic field. The highly active state of the activated material persists for a long time when stored in a dry atmosphere. In some samples, high activity persisted for more than a year. The mechanism of interaction with water is associated with the transfer of aluminum from the grain of the activated material to the solid / water interface through the ternary liquid Al-Ga-In alloy.
The work was supported by the Russian Academy of Sciences and the Federal Agency of Scientific Organizations (project 030320160013).