Self‐Foaming as a Universal Route for Fabricating Liquid Metal Foams and Hollow Particles

Abstract The porous or hollow structure constructed by involving gas inside the liquid metal or liquid metal particles can reduce the density and increase the reaction sites. However, there is no universal route that can place bubbles in liquid metal from macroscale to microscale to prepare liquid metal foams or liquid metal hollow particles. Based on the oxidation reaction of Ga 2 O, self‐foaming as a general route for fabricating liquid metal foams and hollow particles is proposed. Those foams and hollow particles only consist of metal and its oxide, which can avoid the reaction between the liquid metal and the additives to obtain stable properties. The low density (0.6 g cm −3 for foams and 0.71 g cm −3 for hollow particles), the high conductivity (over 10 5 S m −1 ), and the low melting point (≈30.5 °C) are displayed. Besides, those foams and hollow particles can be freely and subjectively modified by other functional particles, such as Fe, Ni, and Si. Those functional foams are used in electromagnetic shielding and the 3D swarming behaviors of liquid metal hollow particles are realized under a magnetic field.