Design of Al–Fe alloys for fast on-board hydrogen production from hydrolysis

Abstract

On-board hydrogen production from the hydrolysis of Al in alkaline water has received great attention because it eliminates the need for hydrogen storage. The Al powder, though providing high reaction rate in the hydrolysis, causes a serious problem of explosive danger when in contact with air or moisture, etc. Since the hydrogen generation rate increases linearly with the corrosion rate of Al to Al³⁺, an Al–Fe alloy, in which an electrochemically noble Al₃Fe phase precipitates along grain boundaries, is designed, and hence causes fast hydrogen generation from the hydrolysis of Al in alkaline water by combined action of galvanic and intergranular corrosion. The Al alloy containing 1 wt% Fe increases the hydrogen generation rate 3.7 times compared with that of pure Al, in which 65% of the increase is due primarily to the galvanic corrosion between Al and Al₃Fe phase, and 35% due to the increase in reaction area by intergranular corrosion.