Abstract:
Reactive force field model (ReaxFF) molecular dynamics simulation was performed to study the stability of supported-atom (or ad-atom) modellabeled as M
1/Cu(111), M=Pt, Ni, Ag, Fe and the embedded (or doped) modelsnoted as M
1@/Cu(111) systems. For the M
1@/Cu(111) catalyst models, it was found that the Pt(Ni, Fe)
1@/Cu(111) is more stable compared to Ag
1@/Cu(111) model (temperature>500 K). For supported-atom models, except for Fe
1/Cu(111) none of them can exist stably at 100~500 K. And these single metal atoms migrate to each other and then aggregate to form large nanoparticles besides Fe atoms diffusing to subsurface as temperature increases. In addition, the effect of H
2 and O
2 atmosphere on the surface of single atom alloy(SAA) catalyst model and thermal stability was invesgated by the optimized Cu/Pt/C/H/O force field parameter. It was found that the presence of H
2 reduces the stability of M
1@Cu(111) catalysts. The simulation results show that M
1/Cu(111) of SAA are not good candidates for catalysts even at relatively low temperature while most M
1@Cu(111) models can exist stable over high reaction temperature.