Hybrid organic-inorganic systems are widely applied in different technological devices thanks to the peculiar combination of molecular functions (e.g., molecular recognition) and solid-state inorganic features (e.g., fast charge and heat transport)[1, 2]. Graphene nanostructures (GNS), for example, can be easily combined with inorganic substrates for designing new energy conversion devices [3]. The objective is to find an effective and cheap alternative to the expensive platinum-based cathodes for oxygen reduction reaction (ORR) in low temperature fuel cells. In this contribution, we report the application of a modified DFT-D approach (DFT-DM) [4] to study a layered hybrid material based on GNS and doped-GNS on a metallic substrate. Experiments support the idea that dopants and a metal surface can enhance GNS catalytic activity [5, 6]. Therefore, with ab initio methods we aim at understanding how the structural, electronic and catalytic properties of GNS are tuned by dopants and by direct interaction with a noble metal surface. First, we discuss minimum-energy geometries, binding energies and electronic structure features of pristine and doped graphene on the hexagonal Ag(111) surface slab. Then, we address the ORR catalysis at the surface of the hybrid electrode. We focus on the reaction intermediates and the minimum energy pathway for the ORR in order to understand the effects of the metal substrate on the physical and chemical properties of GNS. Furthermore, we target the design of new and effective GNS-silver hybrid cathode for low temperature fuel cells by identifying the dopants and/or defects that boost ORR catalysis without weakening the excellent electronic features of graphene. [1] C. De Rosa, F. Auriemma, R. Di Girolamo, G.P. Pepe, T. Napolitano, R. Scaldaferri, Adv Mater, 22 (2010) 5414-5419. [2] A. Hagfeldt, G. Boschloo, L. Sun, L. Kloo, H. Pettersson, Chem Rev, 110 (2010) 6595-6663. [3] A.K. Geim, I.V. Grigorieva, Nature, 499 (2013) 419-425. [4] E. Schiavo, A.B. Muñoz-García, M. Pavone, Manuscript in Preparation [5] F. Sedona, M. Di Marino, D. Forrer, A. Vittadini, M. Casarin, A. Cossaro, L. Floreano, A. Verdini, M. Sambi, Nat Mater, 11 (2012) 970-977. [6] T. Xing, Y. Zheng, L.H. Li, B.C. Cowie, D. Gunzelmann, S.Z. Qiao, S. Huang, Y. Chen, ACS Nano, 8 (2014) 6856-6862.

Molecular oxygen reactivity at graphene-metal interfaces: New insights from first-principles calculations

251st National Meeting (2016)

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