On-demand hydrogen generation by the hydrolysis of ball-milled aluminum composites: A process overview

The hydrolysis of aluminum (Al) is a relatively simple method for on-demand hydrogen generation for niche (low-power, <1 kW) proton exchange membrane fuel cell applications. The hydrolysis of Al in neutral pH water and under standard ambient conditions is prevented by the presence of a thin surficial oxide layer. A promising method to enable Al's spontaneous hydrolysis is by its mechanochemical activation (ball milling) with certain metals (e.g., Bi, Sn, In, Ga). This overview presents several aspects relating to the changes occurring in Al particles during ball milling, e.g., the structural and morphological behavior of Al during ball milling procedures (with and without the presence of activation metals), and the distribution and homogenization of Al and various activation metals. The formation of galvanic cells between anodic Al and cathodic activation metals (relative to Al) is discussed. A summary of the existing Al composites for on-demand hydrogen generation is presented. The paper concludes with a discussion of activation metal recovery, and the effects thereof on the economic feasibility of Al composites for hydrogen generation. (c) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

The study explores the hydrolysis of aluminum for hydrogen generation in proton exchange membrane fuel cell applications. It suggests mechanochemical activation with certain metals to enable spontaneous hydrolysis of aluminum and discusses the formation of galvanic cells in the process. Additionally, it provides a summary of existing aluminum composites and the recovery of activation metals for economic feasibility.