Atomistic insights into heterogeneous reaction of hydrogen peroxide on mineral oxide particles

Recent works have shown that the heterogeneous reaction between mineral dust particles and gaseous hydrogen peroxide plays a significant role in the formation of air pollution. Here, based on ReaxFF molecular dynamics simulations, we investigate this heterogeneous reaction under different relative humidity at the atomic-scale. As a result, the H2O2 and H2O molecules are adsorbed on the silica surface by both molecular and dissociative adsorptions, which resulting in the formation of Si-OH bonds. Besides, the water molecules can compete for the same particle surface sites for the adsorption and decomposition of H2O2 molecules. We found the mineral particles collide randomly to form new particles, which are called New Particle Formation, NPF. It is shown that with the increase of relative humidity, it takes more time to complete the NPF process. This is because more H-bonds were formed in a higher humidity system. The more H-bonds would cause a stronger H-bond network, which leads to the H2O2, and H2O molecules were more difficult to squeeze out. Based on this work, the heterogeneous reaction mechanism is investigated at the atomic level, which has important practical significance for understanding the role of H2O2 and mineral particles in the formation of air pollution.