Regulating Heterogeneous Ice Nucleation via Cation-Specific Modulation of the Electric Double Layer.

Electric-field control of heterogeneous ice nucleation is important for anti-icing and cryopreservation, but the mechanism in electrolyte systems remains unclear. The electrofreezing behavior of supercooled 0.1 M electrolyte droplets containing LiCl, KCl, CsCl, and guanidinium chloride was investigated under low static biases from -1.0 to +1.0 V. In all cases, the nucleation temperature varied nonmonotonically with voltage and reached a maximum at an ion-specific optimal bias. Contact-angle and surface-tension measurements showed that macroscopic wettability and bulk interfacial properties are nearly unchanged across the electrolyte series. By contrast, cyclic voltammetry revealed systematic differences in CV-derived areal capacitance that follow the cation hydration sequence, indicating cation-dependent modulation of the compact electric double layer. On the basis of the Gouy-Chapman-Stern framework, a thermodynamic mechanism was developed showing that the applied bias tunes the Stern-layer electric field and regulates the nucleation barrier through field cancellation. The correlation among cation hydration, interfacial capacitance, and optimal nucleation bias establishes a mechanistic link between ion-specific electric-double-layer structure and electrofreezing. These findings provide a physicochemical basis for low-voltage control of interfacial icing.