Fe–Al core-shell structure as an efficient catalyst for dual hydrogen production and storage by thermochemical water splitting: A reactive molecular dynamic simulation

Abstract

Catalysts with dual functions in hydrogen production and storage are desired for the low-cost technology. In the preceding view, we used reactive force molecular dynamics to demonstrate how effective the Fe–Al core-shell structure is at breaking up water molecules and storing hydrogen free radicals via thermochemical water splitting. The results show that at T ∼600 K, water molecules begin to dissociate in the presence of a Fe–Al catalyst, releasing OH and H free radicals. It is worth noting that the produced OH free radicals are bonded to the Al-shell, whereas the H free radicals move to the Fe-core and stores via chemical bond. Interestingly, at T < 1200 K, there is no Fe–O bond. This could be due to Al having a higher oxidation potential than Fe, causing OH free radicals to preferentially associate with the Al-shell. Furthermore, at 2000K < T > 3000 K, the number of Fe–H bonds decreases while the number of H–H bonds increases, indicating that the stored H atom desorbs and forms an H2 molecule. Temperature can thus be used to monitor the ability of Fe–Al catalysts to dissociate water, store hydrogen, and produce hydrogen. This research shows that developing core-shell type catalysts can provide an effective solution for hydrogen generation, storage, and transportation.