Enhanced Ice Nucleation and Growth by Porous Composite of RGO and Hydrophilic Silica Nanoparticles

A porous composite of 3-dimensional (3D) reduced graphene oxide (rGO) and silica dioxide nanoparticles (PrGO-SN) was synthesized via a single-step hydrothermal process, which can initiate facile ice nucleation and growth starting from temperature as high as −8 °C and 5–8% RH supersaturation and sustain rapid ice crystal growth. The excellent ice nucleation activity of the PrGO-SN composite demonstrates a novel means of ice nucleation relative to known materials, attributed to not only the lattice match between the ice and crystalline structure of the PrGO-SN composite but also higher specific surface area, larger water vapor adsorption capacity, better porosity, and more hydrophilic surface of the composite than rGO. Moreover, environmental scanning electron microscope (E-SEM) in situ observation confirmed detailed growth patterns of ice crystals on the composite, which were affected by the regions with different surface roughness. These findings enabled further understanding of the factors that affected the heterogeneous ice nucleation process and shed light on the design and fabrication of more efficient functional porous ice nucleation materials for many practical applications such as cloud seeding.