Mechanism of Hg ⁰ and O ₂ Interaction on the IrO ₂ (110) Surface: A Density Functional Theory Study

Efficient and effective control of airborne Hg ⁰ emission during fossil fuels utilization is one of many challenges. The catalytic oxidation of Hg ⁰ to Hg ²⁺ is a promising approach for mercury removal as it enables mercury capture at existing air pollution control devices. In this study, IrO ₂ was studied in detail based on density functional theory to show the interactions between Hg ⁰ and O ₂ on the IrO ₂ (110) surface. On the basis of the full optimizations of the IrO ₂ (110) surface, five stable Hg adsorption configurations have been identified, among which the most stable adsorption position was found to be at the top of a 5-fold coordinated Ir atom (Ir _cus-top ). Furthermore, in-depth analysis of the interactions between the Hg atom and O atom on the IrO ₂ (110) surface showed that the adsorption energy of O is higher than that of Hg ⁰ on the Ir _cus-top . Moreover, the results suggest that the preadsorption of O atoms has a positive effect on the adoption of Hg, while the adsorption was identified as a chemisorption. More importantly, the Langmuir-Hinshelwood mechanism was determined to be the most probable reaction mechanism. This study provides insight into the prediction of the potential Hg ⁰ catalytic oxidation by O ₂ on the IrO ₂ (110) surface.