Ab Initio Study of Formation Mechanisms and Thermochemical Properties of Reactive Oxygen Species (ROS) in Photocatalytic Processes

This study explores the thermochemical properties and formation mechanisms of reactive oxygen species (ROS) relevant to photocatalytic processes, aiming to clarify their molecular characteristics and reaction dynamics. The research focuses on key ROS, including the superoxide anion radical (^•O₂^-), hydrogen peroxide (H₂O₂), singlet oxygen (¹O₂), and hydroxyl radical (^•OH), employing Møller-Plesset second-order perturbation theory (MP2)-level quantum chemical calculations. Solvent effects were modeled using water to simulate conditions commonly found in photocatalytic environments. The computed energetic profiles and stabilities of the ROS offer insights into their relative reactivities and possible interconversion pathways. These findings enhance the understanding of how ROS behave under photocatalytic conditions, with implications for their role in degradation mechanisms and redox cycles. Overall, the results support the development and optimization of photocatalytic technologies for environmental applications, including pollutant degradation and disinfection of water and air.