Abstract
Doping carbon materials have proved to be the front runners to substitute for Pt as oxygen reduction reaction (ORR) catalysts. Fluorine-doped graphene (FG) has rarely been used as ORR catalyst because of the difficulty in preparation. Herein, we report FG sheets prepared by a thermal pyrolysis graphene oxide (GO) process in the presence of zinc fluoride (ZnF2) as an efficient electrocatalyst for ORR in the alkaline medium. The results show that the pyrolysis temperature seriously affected the doped fluoride amount and morphology of catalyst. It is found that the FG-1100 catalyst possesses a more positive onset potential, higher current density and better four-electron process for ORR than other FG samples. FG-1100 displays an outstanding ORR catalytic activity that is comparable to that of the commercial Pt/C catalyst. Also, its durability and methanol tolerance ability are superior to those of the commercial Pt/C. The excellent ORR catalytic performance is closely related to its higher doped fluorine amount and wrinkle morphology. The FG catalyst can be developed as a low-cost, efficient and durable catalyst as a viable replacement for the Pt/C catalyst, promoting the commercialization of fuel cells.
Highlights
Oxygen reduction reaction (ORR) plays a pivotal role in clean energy conversion applications such as fuel cells and& 2018 The Authors
The oxygen reduction reaction (ORR) performances of Fluorine-doped graphene (FG) catalyst were evaluated by electrochemical methods, including cyclic voltammograms (CV), rotating disc electrode (RDE) voltammograms, ringdisc electrode (RRDE) voltammograms and chronoamperometry, using a CHI 660E electrochemical workstation (Chenhua, Shanghai) in a conventional three-electrode system at room temperature
As the pyrolysis temperature rose to 11008C, the diffraction peaks of FG-1100 became weaker, suggesting less degree of graphitization
Summary
Oxygen reduction reaction (ORR) plays a pivotal role in clean energy conversion applications such as fuel cells and. Carbon-based materials have proved to be front runners to substitute for Pt as ORR catalysts, possessing excellent catalytic activity and good resistance to methanol crossover effects [22]. XGnPs showed remarkable electrocatalytic activities toward ORR with a high selectivity, good tolerance to methanol crossover/CO poisoning effects and excellent long-term cycle stability. They thought the edge-halogenations play an important role in significantly improving the ORR activity of graphite. The results address a new, low-cost, mass production FG graphene as metal-free efficient ORR catalyst for fuel cells and provide useful information to enucleate ORR mechanisms of carbon-based materials doped with heteroatoms
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