Oxygen Reduction at the Liquid-Liquid Interface: Bipolar Electrochemistry through Adsorbed Graphene Layers

The reduction of oxygen and protons at the interface between two immiscible electrolyte solutions (ITIES) has received a great deal of interest over the last decade, with various materials being used to catalyse these reactions. Probing the mechanisms through which these reactions proceed when using interfacial catalysts is important from both from the perspective of fundamental understanding and for catalyst optimisation. Herein, we have used interfacial-assembled graphene to probe the importance of simple electron conductivity towards the catalysis of the oxygen reduction reaction (ORR) at the ITIES, and a bipolar setup to probe the homogeneous/heterogeneous nature of the ORR proceeding through interfacial graphene. We found that interfacial graphene provides a catalytic effect towards the reduction of oxygen at the ITIES, proceeding via the heterogeneous mechanism when using a strong reducing agent.