APS March Meeting 2015
Volume 60, Number 1
Monday–Friday, March 2–6, 2015;
San Antonio, Texas
Session Q27: Focus Session: Chemical Physics of Clusters: Bridging from Angstrom-scale Clusters to Micron-scale Aerosol Particles IV
2:30 PM–4:54 PM,
Wednesday, March 4, 2015
Room: 204B
Sponsoring
Unit:
DCP
Chair: Barbara Wyslouzil, Ohio State University
Abstract ID: BAPS.2015.MAR.Q27.5
Abstract: Q27.00005 : Cluster size matters: Size-driven performance of subnanometer clusters in catalysis, electrocatalysis and Li-air batteries
3:42 PM–4:18 PM
Preview Abstract
Abstract
Author:
Stefan Vajda
(Argonne National Laboratory)
This paper discusses the strongly size-dependent performance of subnanometer
cluster based catalysts in 1) heterogeneous catalysis, 2) electrocatalysis
and 3) Li-air batteries.
The experimental studies are based on I. fabrication of ultrasmall clusters
with atomic precision control of particle size and their deposition on oxide
and carbon based supports; II. test of performance, III. \textit{in situ }and \textit{ex situ} X-ray
characterization of cluster size, shape and oxidation state; and IV.electron
microscopies.
\textit{Heterogeneous catalysis}.
The pronounced effect of cluster size and support on the performance of the
catalyst (catalyst activity and the yield of C$_{n}$ products) will be
illustrated on the example of nickel and cobalt clusters in Fischer-Tropsch
reaction.
\textit{Electrocatalysis.}
The study of the oxygen evolution reaction (OER) on size-selected palladium
clusters supported on ultrananocrystalline diamond show pronounced size
effects. While Pd$_{4}$ clusters show no reaction, Pd$_{6}$ and Pd$_{17}$
clusters are among the most active catalysts known (in in terms of turnover
rate per Pd atom). The system (soft-landed Pd$_{4}$, Pd$_{6}$, or Pd$_{17}$
clusters on an UNCD Si coated electrode) shows stable electrochemical
potentials over several cycles, and the characterization of the electrodes
show no evidence for evolution or dissolution of either the support
Theoretical calculations suggest that this striking difference may be a
demonstration that bridging Pd-Pd sites, which are only present in
three-dimensional clusters, are active for the oxygen evolution reaction in
Pd$_{6}$O$_{6}$.
\textit{Li-air batteries.}
The studies show that sub-nm silver clusters have dramatic size-dependent
effect on the lowering of the overpotential, charge capacity, morphology of
the discharge products, as well as on the morphology of the nm size building
blocks of the discharge products. The results suggest that by precise
control of the active surface sites on the cathode, the performance of
Li-air cells can be significantly improved
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2015.MAR.Q27.5