Reply to the 'Comment on "The chemical reactions in electrosprays of water do not always correspond to those at the pristine air-water interface"' by A. J. Colussi and S. Enami, Chem. Sci., 2019, 10, DOI: 10.1039/c9sc00991d.

The air-water interface serves as a crucial site for numerous chemical and physical processes in environmental science and engineering, such as cloud chemistry, ocean-atmosphere exchange, and wastewater treatment. The development of "surface-selective" techniques for probing interfacial properties of water therefore lies at the forefront of research in chemical science. Recently, researchers have adapted electrospray ionization mass spectrometry (ESIMS) to generate microdroplets of water to investigate interfacial phenomena at thermodynamic equilibrium. In contrast, using a broad set of experimental and theoretical techniques, we found that electrosprays of water could facilitate partially hydrated (gas-phase) ions (e.g., H3O+·(H2O)2) to drive/catalyze chemical reactions that are otherwise not possible to accomplish by purely interfacial effects (e.g., enhanced water-hydrophobe surface area) (Chem. Sci., 2019, 10, 2566). Thus, techniques exploiting electrosprays of water cannot be relied upon as generalized surface-selective platforms. Here, we respond to the comments raised by Colussi & Enami (Chem. Sci., 2019, 10, DOI: ; 10.1039/c9sc00991d) on our paper.