Polyelectrolytes Functionalized Graphene as Metal-Free Electrocatalysts for Oxygen Reduction

This work reports PDDA and QHECE-functionalized graphene nanosheets (N-GNSs) as metal-free catalyst for the oxygen reduction reaction in alkaline media. Although GNSs, PDDA or QHECE alone has little catalytic activity, their hybrid exhibits an unexpected high ORR activity. The structure, morphology, composition, and surface properties of the N-GNSs catalysts were characterized by transmission electron microscopy (TEM), and linear sweep voltammetry (LSV) as well as rotating disk electrode (RDE) techniques. An enhancement in the ORR electrocatalytic activity on N-GNSs was observed with increasing the mass ratio of N:GNSs, where QHECE:GNSs = 1:4 exhibits the highest activity for the ORR with onset potential and the half-wave potential of 0.06V and -0.1V, respectively.