Evaluating the chemical kinetics of aluminium/alumina/water reactions using molecular dynamics

H Zhao and YJ Zhang and YC Liu and ZH Huang, COMPUTATIONAL MATERIALS SCIENCE, 257, 113982 (2025).

DOI: 10.1016/j.commatsci.2025.113982

Strength of aluminium in generating heat and hydrogen through water reaction highlight its potential as a green hydrogen carrier, but the formation of a passive oxide layer (alumina) inhibits further reactions thus hydrogen yield. This study employs reactive molecular dynamics (MD) simulations with the ReaxFF force field to investigate interactions between water and alumina-coated aluminium surfaces at temperatures ranging from 1000 K to 2500 K. Analysis of diffusion-driven reaction kinetics shows that hydrogen generation is primarily controlled by hydrogen atom diffusion within the aluminium bulk. Higher temperatures significantly accelerate both diffusion and reaction rates, shifting the mechanism from diffusion-limited to chemically controlled. Atomic-level reaction pathway analysis, using an in-house atom status tracing code, reveals the dynamic evolution of aluminium atom states. The results emphasize the roles of hydrogen and oxygen diffusion and indicate that O-H bond cleavage mainly proceeds through internal atomic diffusion. These findings offer detailed atomic-scale insight into the aluminium- water reaction, capturing both oxidizer diffusion and thermal effects. The study highlights the importance of thermal activation in enhancing reaction efficiency and safety, reinforcing aluminium's potential for green hydrogen production in carbon-neutral energy systems.

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