Synthesis of a magnetic-based yolk-shell nano-reactor: A new class of monofunctional catalyst by Cu0-nanoparticles and its application as a highly effective and green catalyst for A3 coupling reaction

Abstract

A novel and yolk/shell nanoreactor catalyst (H-Fe3O4@h-Cu0@m-SiO2) was designed and synthesized with a hollow magnetite core encapsulated in a mesoporous silica shell which Cu0-nanoparticles were decorated in the interior cavity shell in order to enhance the catalytic activity. The morphology, structure and physicochemical properties of the yolk/shell nanoreactor were then fully characterized by using high resolution transmission electron microscopy (HRTEM), field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction patterns (XRD), Fourier transform infrared spectroscopy (FT-IR). The N2 absorption-desorption isotherms indicate a Brunauer–Emmett–Teller (BET) specific surface area of 287.36 m2/g and a pore width of 2–50 nm. Applied as a catalyst for three-component A3 coupling reaction of alkynes, aldehydes and amines under the optimized condition. Interestingly, the characterization results indicate that (H-Fe3O4@h-Cu0@m-SiO2) has great catalytic performance, which could be related to unique hollow morphology with an active core contains Cu0-nanoparticles, protective mesoporous shell and hollow void. This aspect of morphology leads to favoring the transfer of the reactants and products. Reusability up to 10 times without any obvious decline in catalytic activity and short reaction time are other advantageous of this green nano-reactor. Keywords: Hallow sphere nanoparticles, Porous shell, Yolk/shell nanoreactor, Coupling reaction