An overview of the electrochemical performance of modified graphene used as an electrocatalyst and as a catalyst support in fuel cells

•Modified graphene is used as an electrocatalyst and catalyst support for fuel cells.•The chemical modification effects on the graphene are explored.•Highlights of electrochemical performances of various modified graphene. Fuel cells have recent drawn particular attention from scientists because they are both environmental friendly and highly efficient energy devices. Nevertheless, the commercialization of fuel cells is restricted by the high cost of Pt and the low stability of carbon supports, which are susceptible to corrosion. Graphene is a carbon support that may be able to replace carbon black because it offers a larger active surface area and better resistance toward corrosion. In this paper, graphene-supported Pt-based materials and non-Pt metals are compared to the analogous systems supported on carbon black. The primary issues attributed to graphene are its poor dispersion in solvent and electrochemical inertness. These issues can be resolved by modifying the structure of graphene, obtaining the desired chemical and physical properties through heteroatom doping or chemical functionalization. The properties of the modified graphene include improved solubility in solvent, which is attributed to the presence of foreign atoms or molecules on the graphene sheet; this change leads to a modification of its hydrophilicity. The effects of these additional functional groups or substituted elements on the electrochemical performance of the graphene catalysts in a fuel cell system are discussed herein. In the later sections of this paper, the applications of modified graphene as a catalyst support and as an electrocatalyst for fuel cells are reviewed.