The Effect of KOH Treatment on the Chemical Structure and Electrocatalytic Activity of Reduced Graphene Oxide Materials.

Reduced graphene oxide (rG-O)-based materials have great potential as metal-free electrocatalysts for the oxygen reduction reaction (ORR) owing to their electrical and electrochemical properties and large surface area. Long-term durability and chemical stability of the catalysts in the presence of electrolytes such as aqueous KOH solution are important for their use in practical applications. In this study, three types of rG-O and rG-O-K (rG-O after reaction with KOH) materials were synthesized. The chemical structures, surface areas, and catalytic ORR performances of the rG-O materials were compared with those of the corresponding rG-O-K materials. The onset potentials of the rG-O materials for electrocatalytic reduction of oxygen are almost the same as those of the corresponding rG-O-K materials; however, the current density and the number of transferred electrons are significantly reduced. These data show that the catalytic ORR performance of rG-O-based materials can be altered by KOH.