Insight of external ultrasound on energy-production acceleration from renewable Al-water reaction in Al-based metallic materials

Harnessing renewable metal fuels to supplement conventional bio-mass energy supply in certain areas is steadily demanded under the current global energy policy of CO2 emission reduction. The Al-to-power of a semi-cycle phase in the renewable conception by hydrolysis in aluminum-based metallic materials is viewed promising, yet surficial oxidation of aluminum matrices and the reaction by-products always deactivate the materials. Ultrasound induction in the hydrolysis process is proposed as an effective route to maintain a high-hydrolysis activity, but the trials on metallic materials are still blank. This article addresses the ultrasound accelerated hydrolysis of a representative aluminum-based metallic material, and the process was in-situ explored by high-speed photography to unravel the mechanism along with numerical modelling. The result shows that ultrasound fractures the particle material and exfoliates the reaction by-product layer to instantly expose more fresh aluminum, resulting in accelerated hydrogen generation. Using these discoveries, the employment of ultrasound in exploiting the hydrolysis of Al-based materials to meet the renewable metal-fuel demand is anticipated.