Polyelectrolyte-functionalized graphene as metal-free electrocatalysts for oxygen reduction.

Poly(diallyldimethylammonium chloride), PDDA, was used as an electron acceptor for functionalizing graphene to impart electrocatalytic activity for the oxygen reduction reaction (ORR) in fuel cells. Raman and X-ray photoelectron spectroscopic measurements indicate the charge transfer from graphene to PDDA. The resultant graphene positively charged via intermolecular charge-transfer with PDDA was demonstrated to show remarkable electrocatalytic activity toward ORR with better fuel selectivity, tolerance to CO posing, and long-term stability than that of the commercially available Pt/C electrode. The observed ORR electrocatalytic activity induced by the intermolecular charge-transfer provides a general approach to various carbon-based metal-free ORR catalysts for oxygen reduction.