Dynamic surface wettability of three-dimensional graphene foam

In this work, three-dimensional graphene foams(GFs) are synthesized and characterized by scanning electron microscope(SEM) and Raman spectroscopy. The SEM images indicate that after the growth of graphene, the graphene covers the surface of nickel(Ni) foam uniformly. Raman spectra show that the percentages of monolayer, bilayer, trilayer, and multilayer graphenes are ～ 58%, ～ 32%, ～ 8%, and ～ 2%, respectively. The contact angle(CA)(～ 12?) of water droplet(3 μL) on GF is found to be larger than that on Ni foam(～ 107?), indicating that graphenes have changed the surface wettability of the Ni foam. Meanwhile, the dynamic characteristics of CA of water droplet on GF are different from those on Ni foam. The mechanisms for different behaviors are discussed, which are attributed to volatilization and seepage of water droplets.