Preparation of ice nanofibers with electrospray

• Unconfined ice nanofibers were produced for the first time.
• Ice nanofibers were made by electrospray and hyperquenching method.
• The formation mechanism of ice nanofibers was proposed.

We report here that massive unconfined ice nanofibers are made by electrospraying liquid water into a hyperquenching chamber. Cotton-appeared ice are found on the bottom of the chamber where the temperature is below 140 K and they are confirmed to be ice nanofibers with diameters ranging from several tens to hundreds of nanometers. In contrast to the mechanism for electrospinning polymer nanofibers, we suggest that the formation of the ice nanofibers involves a series of physical processes: droplet evaporation, vapor supersaturation, droplet coalescence and hyperquenching. This study demonstrates for the first time the possibility to make template-free ice nanofibers and may have implication for fundamental studies and industrial applications.