Improved Electron Distribution in Graphene Quantum Dots Carrier by F, N Co-Doping for Electrocatalytic ORR

Rising energy demand has forced to look for new ways to convert energy. Graphene quantum dots (GQD) has received extensive attention in many fields due to their low toxicity, abundant active sites, sound water solubility and photoluminescence stability. Here, a fluorine-nitrogen co-doped GQD (C-GQD) is synthesized for efficient oxygen reduction reaction (ORR) catalysts. The incorporation of fluorine and nitrogen atoms changed the electronic structure of the carbon atom, resulting into synergistic enhancement of catalytic performance toward ORR. Electrochemical studies of the ORR showed that the initial potentials of C-GQD were positively shifted by 200 mV and 170 mV compared with those of GQD and N-GQD, respectively, and the half-wave potentials were positively shifted by 200 mV and 180 mV, which were comparable to that of 20% Pt/C. The CV curves underwent only slight fluctuations after 10,000 cycle tests. The obtained results provide important insights into the use of metal-free catalysts with GQDs as carriers as promising electrocatalysts for proton exchange membrane fuel cells with low cost and easy preparation procedures. Graphical Abstract