Ag-Pt Compositional Intermetallics Made from Alloy Nanoparticles.
Intermetallics are compounds with long-range structural order that often lies in a state of thermodynamic minimum. They are usually considered as favorable structures for catalysis due to their high activity and robust stability. However, formation of intermetallic compounds is often regarded as element specific. For instance, Ag and Pt do not form alloy in bulk phase through the conventional metallurgy approach in almost the entire range of composition. Herein, we demonstrate a bottom-up approach to create a new Ag-Pt compositional intermetallic phase from nanoparticles. By thermally treating the corresponding alloy nanoparticles in inert atmosphere, we obtained an intermetallic material that has an exceptionally narrow Ag/Pt ratio around 52/48 to 53/47, and a structure of interchangeable closely packed Ag and Pt layers with 85% on tetrahedral and 15% on octahedral sites. This rather unique stacking results in wavy patterns of Ag and Pt planes revealed by scanning transmission electron microscope (STEM). This Ag-Pt compositional intermetallic phase is highly active for electrochemical oxidation of formic acid at low anodic potentials, 5 times higher than its alloy nanoparticles, and 29 times higher than the reference Pt/C at 0.4 V (vs RHE) in current density.
University of Illinois at Urbana-Champaign , Department of Chemical and Biomolecular Engineering, 114 Roger Adam Laboratory, MC-712, 600 South Mathews Avenue, Urbana, Illinois 61801, United States.
Yung-Tin
YT
Pan
University of Illinois at Urbana-Champaign , Department of Chemical and Biomolecular Engineering, 114 Roger Adam Laboratory, MC-712, 600 South Mathews Avenue, Urbana, Illinois 61801, United States.
Yuqi
Y
Yan
University of Illinois at Urbana-Champaign , Department of Materials Science and Engineering, 1006 Materials Research Laboratory, 104 South Goodwin Avenue, Urbana, Illinois 61801, United States.
Yu-Tsun
YT
Shao
University of Illinois at Urbana-Champaign , Department of Materials Science and Engineering, 1006 Materials Research Laboratory, 104 South Goodwin Avenue, Urbana, Illinois 61801, United States.
Jian-Min
JM
Zuo
University of Illinois at Urbana-Champaign , Department of Chemical and Biomolecular Engineering, 114 Roger Adam Laboratory, MC-712, 600 South Mathews Avenue, Urbana, Illinois 61801, United States.
Hong
H
Yang
Ag−Pt; electrocatalysis; intermetallic compound; nanoparticle processing