The Aerosol OT + n-Butanol + n-Heptane + Water System: Phase Behavior, Structure Characterization, and Application to Pt70Fe30 Nanoparticle Synthesis

Abstract

A phase diagram of the pseudo-ternary Aerosol OT (AOT)+n-butanol/n-heptane/water system, at a mass ratio of AOT/n-butanol=2, is presented. Conductivity measurements showed that within the vast one-phase microemulsion region observed, the structural transition from water-in-oil to oil-in-water microemulsion occurs continuously without phase separation. This pseudo-ternary system was applied to the synthesis of carbon-supported Pt70Fe30 nanoparticles, and it was found that nanoparticles prepared in microemulsions containing n-butanol have more Fe than those prepared in ternary microemulsions of AOT/n-heptane/water under similar conditions. It was verified that introducing n-butanol as a cosurfactant into the AOT/n-heptane/water system lead to complete reduction of the Fe ions that allowed obtaining alloyed PtFe nanoparticles with the desired composition, without the need of preparing functionalized surfactants and/or the use of inert atmosphere.