Functional nanoparticle-decorated graphene oxide sheets as stabilizers for Pickering high internal phase emulsions and graphene oxide based foam monoliths

Abstract

Metallic oxide nanoparticle-decorated graphene oxide (GO) sheets were easily fabricated by a redox reaction between GO and metal salts, and then could be used to stabilize oil-in-water (O/W) Pickering high internal phase emulsions (HIPEs). Here, the metallic oxide nanoparticles contained Fe₃O₄, TiO₂, and Mn₃O₄ nanoparticles. The effects of the concentrations of the metal salt and GO sheets used to prepare the nanoparticle-decorated GO, the internal phase fraction, and the type of oil phase on the formation and properties of HIPEs were systematically investigated. The results showed that the intermediate GO concentration used to prepare the nanoparticle-decorated GO was helpful for the formation of HIPE. And the average diameter of HIPE droplets decreased with the increase in the concentration of metal salt (iron chloride), but enhanced with the increase in the internal phase fraction. Oils with a large viscosity or containing a benzene ring structure were favorable to forming concentrated emulsions with a high internal phase fraction. Furthermore, the nanoparticle-decorated GO stabilized Pickering HIPE was used as a template to prepare functional GO-based porous foams by polymerizing the Pickering HIPE. This research paves a facile and effective way for the fabrication of functional GO-based O/W Pickering HIPEs and porous materials, which may find a wide variety of applications, such as in magnetic, catalytic and electrochemical fields.