Effect of Argon Gas in Oxygen Catalytic Recombination on a Silica Surface: A Reactive Molecular Dynamics Study

Abstract

Molecular dynamics analysis using a reactive force field (ReaxFF) potential is carried out to investigate microscopically the effect of argon gas in atomic oxygen recombination on a silica surface. The effect of argon atoms is studied by computing both the potential energy surface of incoming atoms and the oxygen recombination efficiency. Potential energy surfaces for oxygen adsorption show that incoming oxygen atoms exhibit more tendency to make a chemical bond with the outer silicon atomic layer. Additionally, the potential energy curves for both oxygen and argon atoms are computed at three different points of interest on the silica surface. The atomic surface recombination process is modeled by imposing a fixed influx boundary condition on the incoming oxygen gas at a partial pressure of 10 atm and temperature of 1000 K. Four different cases of argon gas partial pressure near the surfaces, ranging from 0 to 15 atm, are considered to study the influence of argon atoms on the recombination mechanism. It is observed that the presence of argon atoms has a substantially minor influence on the overall oxygen recombination efficiency on the silica surface.