Synthesis of Different Nano‐layer Shells (Mono‐, Bi‐, and Alloy Layers)‐Coated Gold Spherical Nanoparticles Core for Catalysis

Abstract

Various types of metal layer shells such as mono‐, bi‐, and alloy layer using gold and silver on preformed gold spherical nanoparticles core were synthesizing using sodium borohydride as reducing agent. UV‐vis absorption spectroscopy, transmission electron microscopy images, and X‐ray diffraction techniques were used to characterize the prepared pristine gold spherical nanoparticles and various core‐shell metal nanoparticles. High‐angle annular dark field scanning transmission electron microscopy‐energy dispersive X‐ray spectroscopy mapping images were recorded for the alloy and bilayer shell coated core‐shell nanoparticles. Catalytic reduction of 4‐nitroaniline in the presence of sodium borohydride was taken to study the catalytic activity of the prepared core‐shell nanostructures. Interestingly, the alloy shell coated gold spherical nanoparticles (AuNP@AgAu) showed the best catalytic activity (higher rate constant; 21.61×10−3 s−1) than that of mono‐, and bilayer core‐shell and pristine gold spherical nanoparticles.