广东工业大学安太成团队报道了ClNO₂在含氯空气-水表面的独特非均相反应机理。相关研究成果于2023年10月9日发表于国际顶尖学术期刊《美国化学会杂志》。

硝基氯（ClNO₂）在空气-水表面的非均相反应在氯的生命周期中起着重要作用。在过冷条件下，空气-水表面在冰面上普遍存在，影响微量气体的吸收和非均相反应过程。先前的研究表明，ClNO₂是N₂O₅吸收后在Cl掺杂的冰表面上形成的。

该文中，使用经典分子动力学（MD）和Born–Oppenheimer MD模拟相结合的方法，在过冷条件下，在含有Cl的空气-水表面上提出了ClNO₂的一种独特的非均相反应机制。研究发现，N₂O₅在顶部空气-水表面离解成NO₂⁺和NO₃^-离子对。在几乎不含任何Cl^–的表面顶层，NO₂⁺通过水解进行反应，生成H₃O⁺和HNO₃。因此，表面酸化是由于H₃O⁺的生成而出现的。随着NO₂⁺扩散到表面深层，NO₂⁺与Cl^–反应形成ClNO₂。

注意，ClNO₂的形成与NO₂⁺水解竞争，ClNO₂形成的速率比NO₂⁺水解的速率大27.7[Cl^–]。之后，ClNO₂与Cl^–的反应在H₃O⁺的催化下变得无障碍，而这在中性表面上是不可行的。因此产生Cl₂并逃逸到大气中（Cl₂的低溶解度），从而形成Cl自由基。所提出的机制支持了目前对ClNO₂的命运及其在极端寒冷环境中的Cl化学作用的理解，如北极和其他高纬度地区的冬季。

附：英文原文

Title: Distinctive Heterogeneous Reaction Mechanism of ClNO2 on the Air–Water Surface Containing Cl

Author: Weina Zhang, Jie Zhong, Ruijing Li, Liwen Li, Xiaohui Ma, Yuemeng Ji, Guiying Li, Joseph S. Francisco, Taicheng An

Issue&Volume: October 9, 2023

Abstract: The heterogeneous reaction of nitryl chloride (ClNO2) on the air–water surface plays a significant role in the chloride lifecycle. The air–water surface is ubiquitous on ice surfaces under supercooled conditions, affecting the uptake and heterogeneous reaction processes of trace gases. Previous studies suggest that ClNO2 is formed on Cl-doped ice surfaces following the N2O5 uptake. Herein, a distinctive heterogeneous reaction mechanism of ClNO2 is suggested on an air–water surface containing Cl under supercooled conditions using combined classic molecular dynamics (MD) and Born–Oppenheimer MD simulations. It is found that N2O5 dissociates into a NO2+ and NO3– ionic pair on the top air–water surface. In the top layer of the surface containing barely any Cl–, NO2+ proceeds through hydrolysis and produces H3O+ and HNO3. Thus, surface acidification appears because of H3O+ yields. With NO2+ diffusion to the deep layer of the surface, NO2+ reacts with Cl– and forms ClNO2. Note that ClNO2 formation competes with NO2+ hydrolysis, and the rate of ClNO2 formation is 27.7[Cl–] larger than that of NO2+ hydrolysis. Afterward, the reaction of ClNO2 with Cl– becomes barrierless with the catalysis by H3O+, which is not feasible on a neutral surface. Cl2 is thus generated and escapes into the atmosphere (low solubility of Cl2), contributing to the Cl radical. The proposed mechanism bolsters the current understanding of ClNO2’s fate and its role in Cl chemistry in extremely cold environments like the Arctic and other high-latitude regions in wintertime.

DOI: 10.1021/jacs.3c07843

Source: https://pubs.acs.org/doi/abs/10.1021/jacs.3c07843