Pyrene adsorption on the surface of an iron oxide nanoparticle: A ReaxFF molecular dynamics study

Abstract

In this work, pyrene adsorption on the surface of a 2-nm iron oxide nanoparticle over the temperature range of 600–2500 K is studied by ReaxFF molecular dynamics simulations. The initial configuration of the iron oxide nanoparticle is determined based on the morphology of particles generated from ethylene pyrolysis with the addition of ferric chloride at 1673 K. The simulation results show that pyrene can be either physically or chemically adsorbed on the surface of the iron oxide nanoparticle to form a core-shell structure, as observed in the experiment. At relatively low temperatures, from 600 to 1200 K, pyrene dimers are produced before they get physically adsorbed on the nanoparticle surface. By contrast, at high temperatures from 2000 to 2500 K, pyrene loses a hydrogen atom through H abstraction by the oxygen atom of the iron oxide, and the pyrenyl radical subsequently attaches to the iron atom to form a C-Fe bond. As to the intermediate temperature range of 1200–2000 K, both physical and chemical adsorptions can occur.