Role of confinement in water solidification under electric fields

In contrast to the common belief that confinement promotes water solidification, here we show by molecular dynamics simulations that confinement can impede water solidification under electric fields. The behavior is evidenced by the increase in critical electric field strength for water solidification as the confinement progresses. We also show that the solidification occurs more easily with a parallel field than a perpendicular one. We understand and generalize these results by developing an energy theory incorporated with the anisotropic Clausius−Mossotti equation. It is revealed that the underlying mechanism lies in the confinement effect on molecules’ electro-orientations. Thus, it becomes possible to achieve electro-freezing (i.e., room-temperature ice) by choosing both confinement and electric fields appropriately.