TY - JOUR
T1 - New insights into the structure of PdAu nanoparticles as revealed by aberration-corrected STEM
AU - Deepak, Francis Leonard
AU - Casillas-Garcia, Gilberto
AU - Esparza, Rodrigo
AU - Barron, H.
AU - Jose-Yacaman, Miguel
N1 - Funding Information:
The authors would like to acknowledge THE WELCH FOUNDATION AGENCY PROJECT # AX-1615 . “Controlling the Shape and Particles Using Wet Chemistry Methods and Its Application to Synthesis of Hollow Bimetallic Nanostructures”. The authors would also like to acknowledge the NSF PREM Grant no. DMR 0934218 , Title: Oxide and Metal Nanoparticles—The Interface between life sciences and physical sciences. The authors would also like to acknowledge RCMI Center for Interdisciplinary Health Research CIHR. “The project described was supported by Award Number 2G12RR013646-11 from the National Center for Research Resources . The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Center for Research Resources of the National Institutes of Health.”
PY - 2011/6/15
Y1 - 2011/6/15
N2 - Bimetallic nanoparticles of AuPd find important applications in catalysis. Their catalytic performance is directly related to the structure, alloy formation and variation of composition in the structure. A standard idea is that bimetallic nanoparticles can be either an alloy or a core shell structure. Our group has investigated the structure and composition of PdAu nanoparticles by using aberration corrected high angle annular dark field scanning transmission electron microscopy (HAADFSTEM). We reported previously that the nanoparticles are composed of an evenly alloyed inner core, an Au-rich intermediate layer, and a Pd-rich outer shell. The structure is more complicated than what simple models can predict. In this paper, we report additional studies of this system wherein by carrying out spectral and chemical analysis (STEMEDS and STEMEELS) the interface structure can now be better identified and understood. Apart from the three-layered core-shell structures, we have also been able to observe in some cases a four-layered core-shell structure as well. The entire core-shell structure is not rigid and there is indeed intercalation of AuPd into the other layers as well. In addition we have been able to locate stacking faults present in the nanoparticles. We also address the problem of the interface structure between the layers. By using nanodiffraction we have found that the whole structure of the nanoparticles becomes hcp in contrast to the bulk structure of Au or Pd.
AB - Bimetallic nanoparticles of AuPd find important applications in catalysis. Their catalytic performance is directly related to the structure, alloy formation and variation of composition in the structure. A standard idea is that bimetallic nanoparticles can be either an alloy or a core shell structure. Our group has investigated the structure and composition of PdAu nanoparticles by using aberration corrected high angle annular dark field scanning transmission electron microscopy (HAADFSTEM). We reported previously that the nanoparticles are composed of an evenly alloyed inner core, an Au-rich intermediate layer, and a Pd-rich outer shell. The structure is more complicated than what simple models can predict. In this paper, we report additional studies of this system wherein by carrying out spectral and chemical analysis (STEMEDS and STEMEELS) the interface structure can now be better identified and understood. Apart from the three-layered core-shell structures, we have also been able to observe in some cases a four-layered core-shell structure as well. The entire core-shell structure is not rigid and there is indeed intercalation of AuPd into the other layers as well. In addition we have been able to locate stacking faults present in the nanoparticles. We also address the problem of the interface structure between the layers. By using nanodiffraction we have found that the whole structure of the nanoparticles becomes hcp in contrast to the bulk structure of Au or Pd.
KW - A1. Defects
KW - B1. Alloys
KW - B1. Metals
KW - B1. Nanomaterials
UR - http://www.scopus.com/inward/record.url?scp=79958710224&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=79958710224&partnerID=8YFLogxK
U2 - 10.1016/j.jcrysgro.2011.04.026
DO - 10.1016/j.jcrysgro.2011.04.026
M3 - Article
AN - SCOPUS:79958710224
SN - 0022-0248
VL - 325
SP - 60
EP - 67
JO - Journal of Crystal Growth
JF - Journal of Crystal Growth
IS - 1
ER -