Theoretical Study on the Mechanisms of Catalytic Hydration of Diiodine Trioxide in Marine Regions

Abstract

Diiodine trioxide (I2O3) is one of the most common iodine oxides in the marine boundary layer (MBL). Both theoretical and experimental studies have confirmed that they can be quickly formed and are relatively stable under dry conditions. However, there is no report on the field observation of I2O3, which means that I2O3 is likely to be lost in the actual marine atmosphere. But the specific loss pathways and mechanisms are still unclear. Considering that the humidity in the marine regions is generally high and the loss of I2O3 will be affected by some substances in the marine atmosphere, water (H2O, W) and iodic acid (HIO3, IA) were selected as a catalyst to investigate the catalytic hydration mechanisms of I2O3 at DLPNOCCSD(T)//ωB97X-D/aug-cc-pVTZ + aug-cc-pVTZ -PP (for iodine) level of theory. The results show that hydration of I2O3 presents a high energy barrier, but IA can reduce it to 3.76 kcal/mol. Therefore, in the marine atmosphere, I2O3 can be hydrolyzed under the catalysis of IA, and cannot directly participate in the new particle formation process.