Mechanistic insight into the competition between interfacial and bulk reactions in microdroplets through N2O5 ammonolysis and hydrolysis
Ye‐Guang Fang, Bo Tang, Chang Yuan, Zhengyi Wan, Lei Zhao, Shuang Zhu, Joseph S. Francisco, Chongqin Zhu, Wei‐Hai Fang
Abstract
Abstract Reactive uptake of dinitrogen pentaoxide (N 2 O 5 ) into aqueous aerosols is a major loss channel for NO x in the troposphere; however, a quantitative understanding of the uptake mechanism is lacking. Herein, a computational chemistry strategy is developed employing high-level quantum chemical methods; the method offers detailed molecular insight into the hydrolysis and ammonolysis mechanisms of N 2 O 5 in microdroplets. Specifically, our calculations estimate the bulk and interfacial hydrolysis rates to be (2.3 ± 1.6) × 10 −3 and (6.3 ± 4.2) × 10 −7 ns −1 , respectively, and ammonolysis competes with hydrolysis at NH 3 concentrations above 1.9 × 10 −4 mol L −1 . The slow interfacial hydrolysis rate suggests that interfacial processes have negligible effect on the hydrolysis of N 2 O 5 in liquid water. In contrast, N 2 O 5 ammonolysis in liquid water is dominated by interfacial processes due to the high interfacial ammonolysis rate. Our findings and strategy are applicable to high-chemical complexity microdroplets.