Hydrolysis Hydrogen Production Mechanism of Mg10Ni10Ce Alloy Surface Modified by SnO2 Nanotubes in Different Aqueous Systems

(Mg-10wt.%Ni)-10wt.%Ce (Mg10Ni10Ce) was ball-milled with SnO2 nanotubes and Mg10Ni10Ce-xSnO2 (x=0, 5, 10 and 15wt.%) composites have been prepared. The phase compositions, microstructures, morphologies and hydrolysis H2 generation performance in different aqueous systems (distilled water, tap water and simulated seawater) have been investigated and the corresponding hydrolysis mechanism of Mg10Ni10Ce and Mg10Ni10Ce-SnO2 has been proposed. Adding a small amount of SnO2 nanotubes can significantly enhance the hydrolysis reaction of Mg10Ni10Ce, especially the initial hydrolysis kinetics and the final H2 generation yield. Unfortunately, the Mg10Ni10Ce-xSnO2 hardly react with distilled water at room temperature. The hydrolysis reaction rate of Mg10Ni10Ce-5SnO2 composite in tap water is still very slow with only 17.3% generation yield after 1 hour at 303 K. Fortunately, in simulated seawater (3.5wt.% NaCl solution), the hydrolytic H2 generation behavior of the Mg10Ni10Ce-5SnO2 composite has been greatly improved, which can release as high as 468.6 mL/g H2 with about 60.9% generation yield within 30 s at 303 K. The Cl- destroys the passivation layer on Mg-Ni-Ce alloy surface and the added SnO2 nanotubes accelerate the hydrolysis reaction rate and enhance the H2 generation yield. The Mg10Ni10Ce-5SnO2 composite can rapidly generate a large amount of H2 in simulate seawater in a short time, which is expected to be applied on portable H2 generators in the future.