Investigation of the effect of temperature and applied electric field on the aluminum-water reaction by ReaxFF molecular dynamics

P Wu and YN Sun and JQ Luo and AC Meng and YF Chen and N Wei and YC Liu, APPLIED SURFACE SCIENCE, 669, 160549 (2024).

DOI: 10.1016/j.apsusc.2024.160549

Hydrogen energy is gaining attention as a non-polluting source. Aluminum 's reaction with water for propulsion and hydrogen production is widely used, but its nanoscale characteristics are unexplored. This study investigated aluminum hydrolysis in water vapor by ReaxFF-MD, examining effects of temperature and electric field. The oxidation of the aluminum surface is accompanied by aluminum dissolution, hydrogen generation and H 3 O + formation, Formed hydrides and oxides were AlH 3 and Al 2 O 3 . Hydrogen disappearance at 700 K and 900 K was due to conversion to AlH 3 . The diffusion of hydrogen and oxygen atoms in the Z direction was enhanced at increasing temperatures, Outer aluminum atoms preferentially reacted with oxygen to form Al 2 O 3 , while inner atoms reacted with hydrogen to form AlH 3 , the loosely packed outer oxide layer contains inclusions of AlH 3 . Studies at room temperature under different electric fields showed -Z field promoted the reaction while + Z field inhibited it, attributed to different electric field strengths ' effect on OH - ion electron-sharing Coulomb equilibrium, resulting in varying rates of hydroxide polar covalent bond cleavage. Our results clarify the atomic-scale effects of temperature and electric field on the aluminum- water reaction, providing guidance for optimizing experimental conditions and enhancing the efficiency of hydrogen production.

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