Influences of Oxidation Degree and Size on the Ice Nucleation Efficiency of Graphene Oxide

Figuring out the influences of carbonaceous particle properties on ice nucleation is important to atmospheric science, but it is still a challenge, especially for experimental investigations due to the coupling effect of multiple properties. Here we separately investigate the effects of oxidation degree and size, two typical and debated factors, on ice nucleation efficiency by choosing graphene oxide (GO) as the model. The results show that with the decrease of oxidation degree, ice nucleation efficiency increases through decreasing the ice nucleation free energy barrier ( $\Delta G_{heter}^{*}$) on GO surface. Interestingly, although the chosen GO sizes are sufficiently large compared with the sizes of critical ice nuclei, the increase of GO size leads to the increase of $\Delta G_{heter}^{*}$ and thus the decrease of ice nucleation efficiency, unlike the general thought that $\Delta G_{heter}^{*}$ is not affected by the particle size any more when the size of particle increases to several times that of the critical ice nucleus.