Koyel Bhattacharyya
Université Paul Sabatier
Koyel Bhattacharyya completed her SB at MIT and her MS at Stanford University in the USA. She is now a doctoral student in her final year in the Mézailles research group at Université Paul Sabatier. She is a member of the Susphos European consortium. During her PhD, she has examined the synthesis of nickel(0) nanoparticles and their conversion to Ni2P, while another branch of her research looks at the synthesis of organophosphines.
Nickel nanoparticles (Ni NPs) are valued for a variety of applications, ranging from catalysis[1] to magnetic properties[2] to the development of more complex nanomaterials[3]. The morphology of these nanoparticles plays a huge role in their behavior. Their size, shape, crystallinity, and surface state greatly affect their properties, and consequently their behavior in practical applications[4,5]. Previously, our lab developed a method for synthesizing size-tunable, monodisperse Ni NPs through the reduction of Ni(acac)2 (acac = acetylacetonate) at high temperature by oleylamine. An associated mechanistic study revealed that water was formed by the dehydration of the acac ligands during the reaction (Scheme 1: Reduction of Ni(acac)2 towards Ni NPs. This method produces water as a byproduct)[6].
Based on our understanding of the mechanism of reduction of Ni(II) into Ni NPs, we present a water-free method of synthesizing monodisperse Ni NPs (Scheme 2: Reduction of Ni(amide)2 to Ni(0)). This approach uses the thermal decomposition of the nickel(II) bis(oleylamide) precursor in the presence of the stabilizing ligand trioctylphosphine (TOP). Varying the ratio of TOP to nickel permits size tunability, resulting in nanoparticles ranging in size from 4 nm in diameter to 11 nm.
The successful extension of this method to Fe and Co NPs will be presented. Finally, metal phosphide nanoparticles may be obtained by heating the metal NPs in the presence of white phosphorus (P4) (Figure 1: Synthesis of Ni2P NPs from Ni(0) NPs).
[1] N. Mézailles, et al. Nano Today 2012, 7, 21–28.
[2] R. D. Tilley, et al. J. Am. Chem. Soc. 2012, 134, 855–858.
[3] (a) N. Mézailles, et al. Chem. Mater. 2011, 23, 2270–2277. (b) N. Mézailles, et al. Chem. Mater. 2012, 24, 688–697.
[4] T. Zhang, et al. J. Phys. Chem. C 2010, 114, 3196–3203.
[5] A. P. Alivisatos, et al. Nature 2005, 437, 664.
[6] N. Mézailles, et al. Chem. Eur. J., 2012, 18(44), 14165–73.
