While electric fields and ionic additives are traditionally considered the primary governing factors of electrohydrodynamic (EHD) cone-jets, this work demonstrates that dissolved CO2 acts as an effective molecular-scale regulator of jet formation and fragmentation. Through systematic molecular dynamics simulations, the EHD cone-jet process of ethanol is investigated under varying electric field strengths, NaCl concentrations, and dissolved CO2 conditions, which have been insufficiently explored at the molecular scale. The results show that increasing electric field strength accelerates Taylor cone formation and jet emission by enhancing electrostatic stresses. The addition of NaCl facilitates jet formation by improving charge transport and weakening hydrogen-bond interactions, thereby affecting jet stability and droplet dispersion. In contrast, dissolved CO2 plays a distinct role compared with electric field and ionic effects. Increasing CO2 concentration accelerates the onset of cone-jet formation and produces thinner jets with more frequent nanoscale fragmentation. Molecular-scale analyses reveal that dissolved CO2 reduces liquid structural compactness and disrupts hydrogen-bond interactions by altering local molecular arrangement and intermolecular spacing. These changes make the liquid interface more susceptible to deformation under an applied electric field, leading to earlier jet formation and enhanced droplet breakup. The coupled evolution of hydrogen-bond number, solvent accessible surface area, cluster number, and interaction energies consistently supports these mechanisms. These findings provide new molecular-level insights into how dissolved CO2 modifies the liquid structure and regulates EHD cone-jet dynamics, offering guidance for EHD cone-jet-based technologies.
Guan et al. (Mon,) studied this question.