On the van der Waals Heteroepitaxy and Hydroxylation/Oxidation States of Au@Muscovite by Pulsed Laser Ablation in Water and Recovery in Aqueous KOH Solution

Abstract

Muscovite powders/flakes immersed in colloidal Au suspension were subjected to pulsed laser ablation under specified pulse energies to form Au@muscovite in various structures and hydroxylation/oxidation states, as characterized by X-ray diffraction, optical/electron microscopy, as well as vibrational and X-ray photoelectron spectroscopy. The fcc-type Au nanoparticles were mainly settled on muscovite flakes by the van der Waals heteroepitaxy {111} Au //(001) mus ; {110} Au −//(110) mus having fair {440} Au /(660) mus coherency, in terms of the close-packed plane match with the SiO 4 face of muscovite, and occasional partial epitaxy (100) Au //(1̅ 10) mus alike the quasi-1-D heteroepitaxy materials. There were also selective Au + /K + replacements to reduce basal layer spacing from 0.99 to 0.92 nm and to form 3 × 3 × 1 superstructure as well as the surface coating of the layered double hydroxides in terms of K + -doped Au lamella and Au(OH) 3 /Au 2 O 3 lamella to give the characteristic 1-D liquid-crystalline diffraction of ∼0.89 and 0.63 nm, respectively. The Au + /K + substitution for muscovite was reversible by immersion in 0.0006 M KOH to have a tailored (002) d-spacing between 0.99 and 0.92 nm. The Au@muscovite flake with K + -doped Au/Au(OH) 3 and Au 2 O 3 coatings had enhanced electrical resistance under ambient conditions for potential CO 2 capture/storage, sensing, and medical applications.