Nano-rod like morphology of Ni@Fe3O4-NDCs on interaction of NDC-supported Fe3O4 with nickel NPs: An efficient catalyst for ligand free Chan-Lam coupling reaction in aqueous medium

Abstract

Nitrogen doped carbons were synthesized and fabricated with magnetite nanoparticles leading to a new magnetic and nitrogen functionalities rich carbon material. This material has dual characteristics as the magnetization of carbons makes it easily separable and the nitrogen moieties act as a binder for both magnetite and metal nanoparticles. This excludes the need for extra binding sites. Nickel and/or iron supported five different catalysts were synthesized and their catalytic activity was tested for Chan-Lam coupling and satisfactory results were obtained with two catalysts- Ni@Fe–Fe3O4–NDCs and Ni@Fe3O4–NDCs, wherein the monometallic counterpart having an upper edge. The characterization of these catalysts provides sufficient evidence for the unexpected enhanced catalytic activity of the monometallic Ni catalyst as compared to its bimetallic counterpart. The most eye-catching thing observed was the difference in morphology of the two synthesized catalysts, which clearly indicated some major changes in the interaction of the metal nanoparticles with the support material in the two catalysts since same method was adopted for the preparation of both. Additional lattice fringes of NiFe2O4 in the HRTEM images along with their corresponding peaks in the XRD spectrum, and the presence of pure Ni2+ species in the XPS spectrum of the monometallic catalyst provides a clear vision of the reason behind the enhanced catalytic activity of the monometallic catalyst. The formation of nano-rod like supported NiFe2O4 particles with increased surface area, mean pore volume and large number of active sites increases the activity of monometallic-Ni for Chan-Lam cross-coupling.

Keywords

• Nitrogen doped carbons
• Magnetic nanoparticles
• Nano-rods like morphology
• Chan-Lam coupling
• Recyclability