title: Quantitative Analysis of the Reduction Kinetics Responsible for the One-Pot Synthesis of Pd-Pt Bimetallic Nanocrystals with Different Structures.
abstract: We report a quantitative understanding of the reduction kinetics responsible for the formation of Pd-Pt bimetallic nanocrystals with two distinctive structures. The syntheses involve the use of KBr to manipulate the reaction kinetics by influencing the redox potentials of metal precursor ions via ligand exchange. In the absence of KBr, the ratio between the initial reduction rates of PdCl4(2-) and PtCl4(2-) was about 10.0, leading to the formation of Pd@Pt octahedra with a core-shell structure. In the presence of 63 mM KBr, the products became Pd-Pt alloy nanocrystals. In this case, the ratio between the initial reduction rates of the two precursors dropped to 2.4 because of ligand exchange and, thus, the formation of PdBr4(2-) and PtBr4(2-). The alloy nanocrystals took a cubic shape owing to the selective capping effect of Br(-) ions toward the {100} facets. Relative to the alloy nanocubes, the Pd@Pt core-shell octahedra showed substantial enhancement in both catalytic activity and durability toward the oxygen reduction reaction (ORR). Specifically, the specific (1.51 mA cm(-2)) and mass (1.05 A mg(-1) Pt) activities of the core-shell octahedra were enhanced by about four- and three-fold relative to the alloy nanocubes (0.39 mA cm(-2) and 0.34 A mg(-1) Pt, respectively). Even after 20000 cycles of accelerated durability test, the core-shell octahedra still exhibited a mass activity of 0.68 A mg(-1) Pt, twice that of a pristine commercial Pt/C catalyst.
authors: The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University , Atlanta, Georgia 30332, United States.|College of Chemistry and Chemical Engineering, Chongqing University , Chongqing 400044, China.
authors: Ming
authors: M
authors: Zhou
authors: The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University , Atlanta, Georgia 30332, United States.
authors: Helan
authors: H
authors: Wang
authors: School of Chemistry and Biochemistry, Georgia Institute of Technology , Atlanta, Georgia 30332, United States.
authors: Madeline
authors: M
authors: Vara
authors: School of Chemistry and Biochemistry, Georgia Institute of Technology , Atlanta, Georgia 30332, United States.|Center for Nanophase Materials Sciences, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.
authors: Zachary D
authors: ZD
authors: Hood
authors: The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University , Atlanta, Georgia 30332, United States.
authors: Ming
authors: M
authors: Luo
authors: The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University , Atlanta, Georgia 30332, United States.
authors: Tung-Han
authors: TH
authors: Yang
authors: The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University , Atlanta, Georgia 30332, United States.
authors: Shixiong
authors: S
authors: Bao
authors: Center for Nanophase Materials Sciences, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.
authors: Miaofang
authors: M
authors: Chi
authors: College of Chemistry and Chemical Engineering, Chongqing University , Chongqing 400044, China.
authors: Peng
authors: P
authors: Xiao
authors: College of Chemistry and Chemical Engineering, Chongqing University , Chongqing 400044, China.
authors: Yunhuai
authors: Y
authors: Zhang
authors: The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University , Atlanta, Georgia 30332, United States.|School of Chemistry and Biochemistry, Georgia Institute of Technology , Atlanta, Georgia 30332, United States.
authors: Younan
authors: Y
authors: Xia