Nanocomposites and Nanomaterials

Kinetics of Formation of Ni-Co Bimetallic Nanoparticles
Kytsya A.R.1,2, Zavaliy I.Y.2, Bazylyak L.I.1, Lytyy P.Y.2,3
1 Department of PhChFF InPOCC NAS of Ukraine. Naukova Str., 3a, Lviv, Ukraine. 
E-mail: andriy_kytsya@yahoo.com
2 Karpenko Physico-Mechanical Institute of the NAS of Ukraine. Naukova Str., 5, Lviv, Ukraine.
3 Lviv Polytechnic National University. Bandery Str., 12, Lviv, Ukraine.

Development of new cheaper and more efficient methods of synthesis of Ni and Co based nanopowders is an actual task of nanochemistry due to promising of these materials for huge range of applications, for example for hydrogen storage systems [1] or hydrogen generation [2]. One of the simplest methods of synthesis of Ni and Co nanoparticles is low-temperature polyol process involved metal-hydrazine complexes as precursor of NiNPs and CoNPs. However, despite the huge range of references devoted to synthesis and utilizing of NiNPs and CoNPs the kinetics of metal nanoparticles and especially bimetallic nanoparticles formation in polyol solutions are studied insufficiently. That is why the aim of presented work was to investigate the kinetics and mechanism of bimetallic Ni-Co nanoparticles formation via reduction of Ni2+ and Co2+ by hydrazine in water-ethylene glycol solutions. It was found that obtained Ni-Co-NPs did not contain any impurities such as oxides or hydroxides. It was observed that the rate of Ni-Co-NPs nucleation is linearly decreased with decreasing of Ni/Co ratio in the reaction mixture from 100/0 to 25/75 but the rate of nanoparticles growth change non-monotonously, that is increased up to Ni/Co ratio 50/50 and is decreased with a further increasing of the content of cobalt. These facts may indicate the changing of mechanism of reduction process due to changing of hydrazine decomposition mechanism from complete decomposition in the presence of Ni to incomplete decomposition with increasing of content of Co. 

1.	Kytsya A.R., Bazylyak L.I., Zavaliy I.Y. et al. Synthesis, structure and hydrogenation properties of Ni-Cu bimetallic nanoparticles // Appl Nanosci.-2021.- https://doi.org/10.1007/s13204-021-01742-6.
2.	Fernandes R., Patel N., Miotello A., Filippi M. Studies on catalytic behavior of Co–Ni–B in hydrogen production by hydrolysis of NaBH4 // J Mol Catal.-2009.-298, N 1-2.-P. 1-6.