title: Analyzing Benzene and Cyclohexane Emulsion Droplet Collisions on Ultramicroelectrodes.
abstract: We report the collisions of single emulsion oil droplets with extremely low dielectric constants (e.g., benzene, ε of 2.27, or cyclohexane, ε of 2.02) as studied via emulsion droplet reactor (EDR) on an ultramicroelectrode (UME). By applying appropriate potentials to the UME, we observed the electrochemical effects of single-collision signals from the bulk electrolysis of single emulsion droplets. Different hydrophobic redox species (ferrocene, decamethyl-ferrocene, or metalloporphyrin) were trapped in a mixed benzene (or cyclohexane) oil-in-water emulsion using an ionic liquid as the supporting electrolyte and emulsifier. The emulsions were prepared using ultrasonic processing. Spike-like responses were observed in each i-t response due to the complete electrolysis of all of the above-mentioned redox species within the droplet. On the basis of these single-particle collision results, the collision frequency, size distribution, i-t decay behavior of the emulsion droplets, and possible mechanisms are analyzed and discussed. This work demonstrated that bulk electrolysis can be achieved in a few seconds in these attoliter reactors, suggesting many applications, such as analysis and electrosynthesis in low dielectric constant solvents, which have a much broader potential window.
authors.affiliation: Center for Electrochemistry, Department of Chemistry, The University of Texas at Austin , 1 University Station A5300, Austin, Texas 78712, United States.
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.affiliation: Center for Electrochemistry, Department of Chemistry, The University of Texas at Austin , 1 University Station A5300, Austin, Texas 78712, United States.
authors.forename: Haiqiang
authors.initials: H
authors.lastname: Deng
authors.affiliation: Center for Electrochemistry, Department of Chemistry, The University of Texas at Austin , 1 University Station A5300, Austin, Texas 78712, United States.
authors.forename: Jeffrey E
authors.initials: JE
authors.lastname: Dick
authors.affiliation: Center for Electrochemistry, Department of Chemistry, The University of Texas at Austin , 1 University Station A5300, Austin, Texas 78712, United States.
authors.forename: Allen J
authors.initials: AJ
authors.lastname: Bard
mesh_terms: D001554:Benzene / Q000737:chemistry*; D003510:Cyclohexanes / Q000737:chemistry*; D004655:Emulsions; D008839:Microelectrodes
chemical_list: D003510:Cyclohexanes; D004655:Emulsions; C506365:Cyclohexane; D001554:Benzene