Date/Time: 04-04-2018 - Wednesday - 05:00 PM - 07:00 PM
Ming Zhao1 Legna Figueroa-Cosme1 Ahmed Elnabawy2 Madeline Vara1 Xuan Yang4 Luke Roling2 Miaofang Chi3 Manos Mavrikakis2 Younan Xia1 4

1, Georgia Institute of Technology, Atlanta, Georgia, United States
2, University of Wisconsin-Madison, Madison, Wisconsin, United States
4, Georgia Institute of Technology, Atlanta, Georgia, United States
3, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States

Nanocages have received considerable attention in recent years for catalytic applications owing to their high utilization efficiency of atoms and well-defined facets. Here we report, for the first time, the synthesis of Ru cubic nanocages with ultrathin walls, in which the atoms are crystallized in a face-centered cubic (fcc) rather than hexagonal close-packed (hcp) structure. The key to the success of this synthesis is to ensure layer-by-layer deposition of Ru atoms on the surface of Pd cubic seeds by controlling the reaction temperature and the injection rate of a Ru(III) precursor. By selectively etching away the Pd from the Pd@Ru core−shell nanocubes, we obtain Ru nanocages with an average wall thickness of 1.1 nm or about six atomic layers. Most importantly, the Ru nanocages adopt an fcc crystal structure rather than the hcp structure observed in bulk Ru. The synthesis has been successfully applied to Pd cubic seeds with different edge lengths in the range of 6−18 nm, with smaller seeds more favorable for the formation of Ru shells with a flat, smooth surface due to a shorter distance for surface diffusion of the Ru adatoms. Self-consistent density functional theory calculations indicate that these unique fcc-structured Ru nanocages might possess promising catalytic properties for ammonia synthesis compared to hcp Ru(0001), on the basis of strengthened binding of atomic N and substantially reduced activation energies for N2 dissociation, which is the rate-determining step for ammonia synthesis on hcp Ru catalysts.

Meeting Program

5:00 PM–7:00 PM Apr 4, 2018 (America - Denver)

PCC North, 300 Level, Exhibit Hall C-E