Influence mechanism of Nano-Fe2O3 on amorphous carbon graphitisation in molecular view via ReaxFF MD simulation

Nano-Fe2O3/C composites are widely used in the electrochemical energy storage field. Preparing nano-Fe2O3/C composites via graphitising the amorphous carbon inserting nano-Fe2O3 particles is potential if the influence mechanism of nano-Fe2O3 on the graphitisation of amorphous carbon is explored in-depth. Here, an amorphous carbon model (a-C model) and a nano-Fe2O3-inserting model (C\Fe2O3 model) were built via the liquid-quench method, and the reaction of Fe2O3 and C during graphitisation was explored via the reactive force field (ReaxFF) simulation. The results showed that nano-Fe2O3 could inhibit the graphitisation of amorphous carbon, and the mechanism was revealed. The Fe2O3 molecules collided with the aromatic carbon layer because of the thermal motion, which caused the breaking of the carbon layer and the generation of CO2 and Fe. Certain Fe reduced from Fe2O3 destroyed the aromatic carbon layers by the strong affinity between Fe and C atoms and generated intercalation compounds (FeCx). Furthermore, the regularisation and stacking of large carbon layers were impeded. Thus, the graphitisation of amorphous carbon was inhibited.