Ion-Specific Effects under Electric Fields on Ice Nucleation at the Mica Surface

Applying external electric fields to mineral surfaces can have a substantial impact on ice nucleation, influencing both climate and atmospheric systems. While earlier studies have demonstrated that electric fields can enhance ice nucleation on nonmineral surfaces, the mechanisms driving heterogeneous ice nucleation (HIN) on mineral surfaces under electric fields with different surface ions remain unclear. In this study, we investigate the ion-specific effects under electric fields on HIN efficiency using mica surfaces containing various cations. Our findings reveal that an upward electric field significantly boosts HIN of water droplets atop Na-mica surfaces, raising the nucleation temperature by approximately 6 °C. In contrast, mica surfaces with other cations or those exposed to a downward electric field show no change in nucleation temperature or HIN efficiency. Molecular dynamics simulations suggest that Na⁺ ions detach more easily from the mica surface under an electric field, exposing more of the flat mica lattice and thus possibly promoting ice nucleation. This study offers new insights into the ion-specific effects of electric fields on HIN, providing a deeper understanding of the role of cations and electric fields in ice nucleation processes.