Tang Bo, Bai Qi, Fang Ye-Guang, Francisco Joseph S, Zhu Chongqin, Fang Wei-Hai
Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China.
Laboratory of Theoretical and Computational Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, China.
J Am Chem Soc. 2024 Aug 7;146(31):21742-21751. doi: 10.1021/jacs.4c05850. Epub 2024 Jul 29.
The activation of halogens (X = Cl, Br, I) by NO is linked to NO sources, ozone concentrations, NO reactivity, and the chemistry of halide-containing aerosol particles. However, a detailed chemical mechanism is still lacking. Herein, we explored the chemistry of the NO···X systems at the air-water interface. Two different reaction pathways were identified for the reaction of NO with X at the air-water interface: the formation of XNO or XONO, along with NO. In the case of the Cl system, the ClNO generation pathway is more favorable, while for the Br and I systems, the formation of BrONO and IONO is barrierless, making them the predominant products. Furthermore, the mechanisms of formation of X from XNO and XONO were also investigated. The high energy barriers of reactions and the high free energies of the products compared to those of the reactants indicate that ClNO is stable at the air-water interface. Contrary to the widely held belief regarding X producing from the reaction of XNO with X, our calculations demonstrate that BrONO and IONO initially form stable BrONO···Br and IONO···I complexes, which then subsequently react with Br and I to form Br and I, respectively. Finally, Br and I decompose to form Br and I These findings have significant implications for experimental interpretation and offer new insights into halogen cycling in the atmosphere.
一氧化氮（NO）对卤素（X = Cl、Br、I）的活化作用与NO源、臭氧浓度、NO反应活性以及含卤化物气溶胶颗粒的化学性质有关。然而，详细的化学机制仍然缺乏。在此，我们探索了气-水界面处NO···X体系的化学性质。在气-水界面处，NO与X的反应确定了两种不同的反应途径：生成XNO或XONO以及NO。对于Cl体系，生成ClNO的途径更有利，而对于Br和I体系，生成BrONO和IONO没有能垒，使其成为主要产物。此外，还研究了由XNO和XONO生成X的机制。与反应物相比，反应的高能垒和产物的高自由能表明ClNO在气-水界面处是稳定的。与普遍认为的XNO与X反应生成X的观点相反，我们的计算表明，BrONO和IONO最初形成稳定的BrONO···Br和IONO···I络合物，随后它们分别与Br和I反应生成Br和I。最后，Br和I分解形成Br和I。这些发现对实验解释具有重要意义，并为大气中的卤素循环提供了新的见解。
