Materials science communication Structural and morphological evaluation of RuePd bimetallic nanocrystals Xianfeng Ma a, c , Rui Lin a , Robert Y. Ofoli a , Zhi Mei b, ** , James E. Jackson c, * a Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, MI 48824, USA b Department of Chemistry, Wayne State University, Detroit, MI 48202, USA c Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA highlights graphical abstract  1. Polyol reduction method generates well-controlled RuePd alloy nanocrystals.  Ru precursor types play a significant role in tuning particle morphology and structures.  Pd to Ru precursor molar ratio con- trols final particle size and composition.  RuePd bimetallic nanocrystals display alloyed structures over full composition space. article info Article history: Received 6 March 2015 Received in revised form 20 October 2015 Accepted 2 February 2016 Available online xxx Keywords: Alloys Nanostructures Chemical synthesis Crystal growth Energy dispersive analysis of X-rays (EDS or EDAX) Electron microscopy (STEM, TEM and SEM) abstract RuePd bimetallic nanocrystals are successfully synthesized via a facile polyol co-reduction method. The resulting nanocrystals show spheres, triangular nanoplates, decahedra, nanorods, and irregular shapes. A combination of Pd II and Ru III precursors tends to yield RuePd bimetallic nanocrystals of higher shape monodispersity than those from Pd II and Ru II precursors. The mole ratio between Ru and Pd components in the precursor solution also plays a key role in determining the size/shape distribution of the nano- crystals, with higher Pd/Ru ratios generating products of more uniform size. Elemental analyses and electron microscopy studies suggest that the obtained nanocrystals have alloyed structures over the full composition space and that they form through either monomer addition or coalescence mechanisms. © 2016 Elsevier B.V. All rights reserved. 1. Introduction Bimetallic nanostructures have attracted great interest for their electronic, optical, and chemical properties which may be distinct from those of either of their pure constituent metals [1e6]. Control over composition, morphology, and structure of bimetallic nano- crystals is desirable as these factors dictate their properties and function. Bimetallic nanocrystal structures may be generally categorized as hetero, core/shell, and alloyed [7,8], and have traditionally been prepared by gaseous or solid state methods [9,10], which require harsh or complicated synthesis conditions with poor control of final crystal composition and structure. However, several controllable * Corresponding author. ** Corresponding author. E-mail addresses: zmei@chem.wayne.edu (Z. Mei), jackson@chemistry.msu.edu (J.E. Jackson). Contents lists available at ScienceDirect Materials Chemistry and Physics journal homepage: www.elsevier.com/locate/matchemphys http://dx.doi.org/10.1016/j.matchemphys.2016.02.003 0254-0584/© 2016 Elsevier B.V. All rights reserved. Materials Chemistry and Physics xxx (2016) 1e6 Please cite this article in press as: X. Ma, et al., Structural and morphological evaluation of RuePd bimetallic nanocrystals, Materials Chemistry and Physics (2016), http://dx.doi.org/10.1016/j.matchemphys.2016.02.003