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Published November 9, 2017 | Supplemental Material
Journal Article Open

The Oxygen Reduction Reaction on Graphene from Quantum Mechanics: Comparing Armchair and Zigzag Carbon Edges


Using density functional theory (PBE-D2 flavor), we report the mechanism for the oxygen reduction reaction (ORR) on graphene sheets. We find that ORR starts with OO chemisorbing onto the carbon edges, rather than the basal plane face, which is not energetically favorable. The carbon edges were described as one-dimensional periodic graphene ribbons with both armchair and zigzag edges. We calculated the binding energies of the ORR products (OO, OOH, O, OH, HOH, HOOH) for the zigzag and armchair edges, examining both the Langmuir–Hinshelwood (LH) and Eley–Rideal (ER), to understand how OO is reduced. For the armchair edge, we calculate an onset potential of 0.55 V vs reversible hydrogen electrode (RHE), which corresponds to −0.22 V at pH 13 in agreement with experiments. We find that the rate-determining step (RDS) to form peroxide (a 2e– process) is hydrogenation of adsorbed OO with a barrier of 0.92 eV. The process to make water (a 4e– process) was found to be unfavorable at the onset potential but becomes more favorable at lower potentials. Thus, undoped carbon catalysts prefer the 2e– mechanism to form peroxide, rather than the 4e– process to form water, which agrees with experiment. The predictions open the route for experimental studies to improve the sluggish ORR on carbon catalysts.

Additional Information

© 2017 American Chemical Society. Received: July 26, 2017; Revised: September 17, 2017; Published: October 10, 2017. This research was supported by the National Institute of General Medical Sciences of the National Institutes of Health under Award Nos. 8UL1GM118979-02, 8TL4GM118980-02, and 8RL5GM118978-02 and NSF grant CBET-1512759 (B.V.M., H.X., and W.A.G.). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. This work is supported by the grants of CSULB Office of Research and Sponsored Program (ORSP) Grant, RSCA Faculty Small Grant, CSULB Start Up Grant, and Southern California Air Quality Management District Grant (T.H.Y.). The authors declare no competing financial interest.

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