466793 Nanoparticle Catalysts Supported on Substitutionally Doped Graphene: Effects on Activity and Stability for Hydrogen Oxidation

Monday, November 14, 2016: 1:30 PM
Franciscan C (Hilton San Francisco Union Square)
Stephen A. Giles1, Stavros Caratzoulas2, Dionisios G. Vlachos2 and Yushan Yan3, (1)Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, (2)Chemical Engineering, University of Delaware, Newark, DE, (3)Chemical & Biomolecular Engineering, University of Delaware, Newark, DE

Fuel cells represent an important part of a renewable future hydrogen-based energy grid. In particular, hydroxide exchange membrane fuel cells (HEMFCs) offer the advantage of non-noble metals being more stable against dissolution than in the acidic environment. However, the rate of the hydrogen oxidation reaction (HOR) decreases by approximately two orders-of-magnitude when switching from acid to base. As a result, developing more efficient and cheaper HOR catalysts is imperative to advancing the current state-of-the-art fuel cells. In a recent publication, we have demonstrated that Ni nanoparticles supported on nitrogen-doped carbon nanotubes (N-CNT) exhibit a threefold increase in the exchange current density relative to a pristine CNT support, and a factor of 30 increase relative to an amorphous carbon support (Zhuang, Z., et al., Nature Communications 2016, 7, 10141). However, a fundamental study on the synergistic interaction between the supported nanoparticle and doped CNT has yet to be done.

Herein, using graphene as a two-dimensional analog for the CNT support used experimentally, we study from first-principles the impact of graphene and doped graphene supports on the hydrogen oxidation reaction occurring on nanometer-sized catalysts. We consider nickel, copper, and silver nanoparticle compositions, and nitrogen-doped, boron-doped, and phosphorous-doped graphene supports. To understand quantitatively the effect of substitutional doping on the nanoparticle/support interaction, we study: 1) the charge transfer between the nanoparticle and support as a function of dopant and dopant location, 2) the modulation of the nanoparticle's d band center due to the presence of a dopant, 3) the interaction of metal adatoms with graphene and doped-graphene, 4) the hydrogen oxidation activity of the nanoparticle/support systems, and 5) the oxidative stability of the supported copper and nickel nanoparticles.

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