380019 A DFT Study of the Oxygen Reduction Reaction Mechanism over the O-Doped Graphene-Supported Pt4/Pt3Fe and Pt3V Alloy Catalysts

Wednesday, November 19, 2014: 1:30 PM
307 (Hilton Atlanta)
Nian Jin1, Hua Wang1, Chaonan Cui1, Xinli Zhu1, Jinyu Han1 and Qingfeng Ge1,2, (1)Key Laboratory for Green Chemical Technology of State Education Ministry, School of Chemical Engineering & Technology, Tianjin University, Tianjin, China, (2)Chemistry and Biochemistry, Southern Illinois University Carbondale, Carbondale, IL

Developing a highly efficient ORR catalyst will have a significant impact on fuel cell applications. The graphene supported Pt3M alloy nanoparticles as ORR catalysts exhibit 3-4 times higher ORR activity than that of the supported Pt catalyst. Here density functional theory calculations were performed to investigate the pathways of the oxygen reduction reaction over the Pt4 and Pt3M (M = Fe, V) clusters supported on the O-doped graphene substrate. The results show that the dangling C atom resulting from oxygen doping becomes an anchor site for metal clusters. Our results also showed that O2 adsorbs as a di-oxygen species on the supported Pt4 and Pt3Fe clusters, but dissociates spontaneously on supported Pt3V. The di-oxygen species dissociates into co-adsorbed HO* and O* upon reduction on both supported Pt4 and Pt3Fe and no stable HOO* intermediates were isolated. On supported Pt4, further reduction via both HO*+HO* and H2O+O* routes is possible, with reaction favoring the HO*+HO* route energetically. On supported Pt3Fe, the HO*+HO* and H2O+O* routes are competitive. On supported Pt3V, the reduction reaction is likely to proceed exclusively through the HO* + HO* route as no stable co-adsorbed H2O and O* state was isolated. The results were discussed in the context of the experimentally observed enhancement of ORR reactivity on the graphene supported Pt3Cr and Pt3Co nanocatalysts.

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See more of this Session: Nanoscale Materials As Catalysts II
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