Edge-iodine/sulfonic acid-functionalized graphene nanoplatelets as efficient electrocatalysts for oxygen reduction reaction†
We report the synthesis of edge-iodine/sulfonic acid-functionalized, graphene nanoplatelets (ISGnPs) via two-step sequential ball-milling of graphite, and their use as electrocatalysts for oxygen reduction reaction (ORR) in fuel cells. Graphite is ball-milled in the presence of iodine to produce the edge-iodine functionalized GnP (IGnP) in the first step and the IGnP is subsequently ball-milled with sulfur trioxide to yield the ISGnP. The resultant ISGnP is highly dispersible in various polar solvents, allowing the fabrication of electrodes for ORR using solution processing. The capacitance and cycle stability of the ISGnP in an alkaline medium are superior to commercial Pt/C and its kinetic electron transfer number (n) is comparable to Pt/C.