Alumina-supported Cu@Ni and Ni@Cu core–shell nanoparticles: Synthesis, characterization, and catalytic activity in water–gas-shift reaction Original Research Article

Novel Cu@Ni catalysts consisting of a Cu core and a Ni shell and Ni@Cu catalysts have been synthesized by successive reduction of Cu and Ni sources dissolved in ethanol. A combination of transmission electron microscopy (TEM), UV–vis spectroscopy, X-ray diffraction (XRD), CO chemisorption, as well as thermogravimetric analysis (TGA) was used to characterize the core–shell nanoparticle catalysts. The powder XRD patterns, CO chemisorption data, and UV–vis spectra indicated the formation of core–shell structures in the bimetallic Cu–Ni nanoparticles. Cu5@Ni5 and Ni5@Cu6.5 nanoparticles with an average particle size of 4.7 and 5.4 nm, respectively, were observed in TEM images. Alumina-supported Ni@Cu nanoparticle catalysts were found to possess similar activity in the water–gas-shift (WGS) reaction to supported Cu catalysts, while supported Cu@Ni catalysts showed comparable WGS activity to supported Ni catalysts and reduced extent of undesirable methanation side-reaction.