Nanocomposites and nanomaterials

Synthesis, structure and hydrogenation properties 
of Ni-Cu bimetallic nanoparticles
Kytsya A.R.1,2, Bazylyak L.I.2, Zavaliy I.Yu.1, Verbovytskyy Yu.V.1, Zavalij P.3
1 Physico-Mechanical Institute NAS of Ukraine, Naukova str. 5, Lviv, 79060, Ukraine; E-mail: andriy_kytsya@yahoo.com
2 Department of Physical Chemistry of Fossil Fuels of the Institute of Physical- Organic Chemistry and Coal Chemistry named after L. M. Lytvynenko of the National Academy of Sciences of Ukraine. Naukova Str. 3а, Lviv, 79060, Ukraine
3 Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA.

Bimetallic nanoparticles are the promising materials for a wide range applications due to combination of different properties in the separate particle. From this point of view Ni-based nanoparticles are very attractive due to combination of magnetic properties and good oxidative stability of Ni, which can be supplemented by catalytic, optical etc activities. The structure of the bimetallic nanoparticles depends on the thermodynamic compatibility of the components as well as on the method of their synthesis. For example, the joint reducing of metal precursors in homogeneous solutions leads mostly to the formation of the structures with non-ordered localization of atoms; using two-step (so-called “seed-mediated”) techniques it is possible to obtain core-shell nanostructures etc. 
Herein we present the study of structure of bimetallic Ni-Cu nanoparticles obtained by fast and simple one-pot reducing of Ni(OH)2/Cu(OH)2 pulp by hydrazine in water/ethylene glycol solutions. Using SEM it was found that the all obtained nanopowders are polydisperse with the particles sizes within 20 – 70 nm and the mean diameters of particles slightly depends on the Ni/Cu ratio. Using XRD it was found that with increasing of Cu in initial mix from 20 to 50 % the lattice parameter for Ni phase increases from 3.527 to 3.560 Å but the lattice parameter of Cu changes more slightly (3.594 … 3.606 Å). At the same time using precisive EDX technique it was found that obtained nanoparticles may be considered as core-shell type in which core consist of the copper but shell consist of nickel-copper solution.
The transition metals in nanostate are widely used as catalysts for hydrogen evaluation and different types of hydrogenation reactions. In this work we paid substantial attention to electrochemical hydrogenation of the synthesized materials. The obtained peculiarities for bimetallic nanoparticles with different Ni/Cu ratio will be discussed and compared with that for pure nano-Ni.