Dispersion, Assembly and Electrochemistry of Graphene at the Liquid|Liquid Interface

Abstract

The dispersion of graphene in 1,2-dichloroethane (DCE), its subsequent attachment at the water|DCE interface and the reduction of oxygen at the water|DCE interface proceeding via interfacial graphene have been investigated.Using addition of an electrolyte which screens surface charge, it was found that electrostatic repulsions play a significant role in determining the kinetic stability of lyophobic non-aqueous graphene dispersions. The onset of aggregation was determined and it was found that dispersions prepared from higher-oxygen content graphite were more stable than those prepared from lower-oxygen content graphite, indicating that oxygen content is important in determining the surface charge on graphene in non-aqueous dispersion.The presence of organic electrolyte was also found to promote assembly of graphene into a coherent film at the liquid|liquid interface. Measurement of the liquid|liquid interfacial tension and three-phase contact angle revealed that the energetics of particle attachment did not change in the presence of organic electrolyte, thus indicating a mechanism of inter-particle electrostatic repulsion minimisation through surface charge screening.Interfacial graphene was found to display a catalytic effect toward the oxygen reduction reaction at the water|DCE interface. A bipolar cell was developed which showed that this reaction occurs heterogeneously, with graphene acting as a conduit for electrons across the water|DCE interface.

Date of Award	31 Dec 2015
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Robert Dryfe (Supervisor)