Factors that Affect Pickering Emulsions Stabilized\nby Graphene Oxide

Abstract

Stable\nPickering emulsions were prepared using only graphene oxide\n(GO) as a stabilizer, and the effects of the type of oil, the sonication\ntime, the GO concentration, the oil/water ratio, and the pH value\non the stability, type, and morphology of these emulsions were investigated.\nIn addition, the effects of salt and the extent of GO reduction on\nemulsion formation and stability were studied and discussed. The average\ndroplet size decreased with sonication time and with GO concentration,\nand the emulsions tended to achieve good stability at intermediate\noil/water ratios and at low pH values. In all solvents, the emulsions\nwere of the oil-in-water type, but interestingly, some water-in-oil-in-water\n(w/o/w) multiple emulsion droplets were also observed with low GO\nconcentrations, low pH values, high oil/water ratios, high salt concentrations,\nor moderately reduced GO in the benzyl chloride–water system.\nA Pickering emulsion stabilized by Ag/GO was also prepared, and its\ncatalytic performance for the reduction of 4-nitrophenol was investigated.\nThis research paves the way for the fabrication of graphene-based\nfunctional materials with novel nanostructures and microstructures.