The electronic behaviors during the interaction and charge transfer between phases at the interface of solid (magnetite)-liquid (water)-gas (nitrogen) was studied using density functional theory (DFT) calculations. It was found that the s- and p-orbital electrons of the N atoms from nitrogen molecules and the O atoms from water molecules interact with the s-, p-, and d-orbital electrons of the Fe atoms from Fe3O4 during contact. Consequently, electrons are transferred, mainly over the contact interface between the phases and the bonds in reactant molecules expand providing favorable conditions for reactions. They were all confirmed theoretically. The effect of humidity on contact electrification was also investigated. It was proved that as the humidity increased, more and more charge “flew” across the solid surface and the reason for the increase in ammonia production along with increasing humidity was explained in the regard of contact electrification. This study can help to better understand the electronic behavior and charge transfer mechanism during solid-liquid-gas contact electrification and provide benefits for selection and rational design of more efficient ammonia synthesis catalysts.
Ryu et al. (Wed,) studied this question.