Hydrogen production by ultrasound assisted liquid laser ablation of Al, Mg and Al-Mg alloys in water

The generation of hydrogen upon ablation of Al, Mg and three different Al-Mg alloys targets immersed in water with and without the presence of an ultrasonic field is reported. The effect of the laser fluence used for ablation of each target on the amount of hydrogen produced was investigated. In general terms as the laser fluence increases a higher amount of hydrogen was obtained. It was found that the simultaneous application of an ultrasonic field enhances approximately 100% the hydrogen production. The proposed procedure performed under standard conditions of temperature and pressure consumes only water and very low amounts of material leading to maximum production rates close to 23.2 mmol/min per gr. Additionally, some of the nanostructures produced during the ablation process were characterized by SEM, TEM, XRD and PL. The results reveal that crystalline Mg₂Al(OH)₇ nanosheets with maximum size close to 100 nm and regular shapes are obtained when the alloy with the maximum aluminum content is ablated at the highest laser fluence under the ultrasonic field.