Zhang Dongmei, Wang Jie, Chen Huan, Gong Chu, Xing Dong, Liu Ziao, Gladich Ivan, Francisco Joseph S, Zhang Xinxing
College of Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Renewable Energy Conversion and Storage Centre, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Frontiers Science Centre for New Organic Matter, Nankai University, Tianjin 300071, China.
Department of Earth and Environmental Science and Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6316, United States.
J Am Chem Soc. 2023 Mar 22;145(11):6462-6470. doi: 10.1021/jacs.3c00300. Epub 2023 Mar 13.
Due to the adverse health effects and the role in the formation of secondary organic aerosols, hydroxyl radical (OH) generation by atmospheric fine particulate matter (PM) has been of particular research interest in both bulk solutions and the gas phase. However, OH generation by PM at the air-water interface of atmospheric water droplets, a unique environment where reactions can be accelerated by orders of magnitude, has long been overlooked. Using the field-induced droplet ionization mass spectrometry methodology that selectively samples molecules at the air-water interface, here, we show significant oxidation of amphiphilic lipids and isoprene mediated by water-soluble PM at the air-water interface under ultraviolet A irradiation, with the OH generation rate estimated to be 1.5 × 10 molecule·s·m. Atomistic molecular dynamics simulations support the counter-intuitive affinity for the air-water interface of isoprene. We opine that it is the carboxylic chelators of the surface-active molecules in PM that enrich photocatalytic metals such as iron at the air-water interface and greatly enhance the OH generation therein. This work provides a potential new heterogeneous OH generation channel in the atmosphere.
由于大气细颗粒物（PM）对健康的不利影响以及在二次有机气溶胶形成中的作用，大气细颗粒物在本体溶液和气相中产生羟基自由基（OH）一直是特别受研究关注的课题。然而，大气水滴气-水界面处的PM产生OH的情况长期以来一直被忽视，而在这个独特的环境中，反应速率可加快几个数量级。在这里，我们使用场诱导液滴电离质谱方法，该方法能在气-水界面选择性地对分子进行采样，结果表明在紫外A照射下，水溶性PM在气-水界面介导了两亲性脂质和异戊二烯的显著氧化，估计OH产生速率为1.5×10分子·秒·米。原子分子动力学模拟支持了异戊二烯对气-水界面的反直觉亲和力。我们认为，是PM中表面活性分子的羧酸螯合剂在气-水界面富集了光催化金属如铁，并极大地增强了其中OH的产生。这项工作为大气中潜在的新的非均相OH产生通道提供了依据。
