Design of ternary Al-Sn-Fe alloy for fast on-board hydrogen production, and its application to PEM fuel cell

Abstract

An Al-Sn-Fe alloy is designed to increase the hydrogen generation rate even in weak alkaline water through the effective removal of Al oxide. Al-1wt.%Sn-1wt.%Fe alloy exhibits the hydrogen generation rate about 6 times higher than pure Al and 1.6 times higher than Al-1wt.%Fe alloy. Increases in exchange current density of Al alloys are in good accordance with increases in hydrogen generation rate. The addition of Sn in Al-Fe alloy can increase the hydrolysis rate by accelerating the breakdown of passive film (Al(OH)(3) and Al2O3) in an alkaline solution. Hence, the Al-1wt.%Sn-1wt%Fe alloy shows a much higher hydrogen generation rate than pure Al and Al-1wt.%Fe alloy in relatively weak alkaline water. In the hydrolysis of Al-1wt.%Sn-1wt%Fe, Fe accelerates the hydrogen production by inducing simultaneously both inter-granular and galvanic corrosion, whereas Sn increases the hydrogen generation rate by breaking the Al oxide down effectively. Based on the increase in the hydrogen generation rate of Al-1wt.%Fe and Al-1wt.%Sn-1wt%Fe alloys over pure Al, the contribution to the increase of Fe and Sn are calculated to be 63% and 27%, respectively. Because the same amount of power is obtained by PEMFC using 6 times less Al-Sn-Fe alloy than pure Al, the weight and volume of on-board hydrogen production reactor can be reduced significantly by alloying Al with a small amount of Fe and Sn. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.