Low-Cost Preparation of Wafer-Scale Au(111) Single Crystals for the Epitaxy of Two-Dimensional Layered Materials.

Abstract

Single-crystal Au(111), renowned for its chemically inert surface, long-range "herringbone" reconstruction, and high electrical conductivity, has long served as an exemplary template in diverse fields, <i>e.g.</i>, crystal epitaxy, electronics, and electrocatalysis. However, commercial Au(111) products are high-priced and limited to centimeter sizes, largely restricting their broad applications. Herein, a low-cost, high-reproducible method is developed to produce 4 in. Au(111) single crystals from commercial Au foils, <i>via</i> an abnormal grain growth process. This methodology involves the initial preparation of a (100)-textured Au polycrystalline foil, followed by the evolution and continuous expansion of an Au(111) abnormal grain through one-site stress loading and stress-relief annealing in an Ar/H₂ atmosphere. Theoretical simulations indicate that stress/strain and high-temperature treatments in the H₂ atmosphere induce an intermediate disordered state, facilitating the evolution from polycrystalline Au(100) foil to single-crystal Au(111) foil. Furthermore, the resulting Au(111) foils have been utilized as model substrates for the oriented growth of two-dimensional transition metal dichalcogenides and their heterostructures with graphene. This work hereby puts forward an effective approach for large-scale, cost-effective production of metal single crystals, potentially revolutionizing their applications across various fields, from materials sciences to electronics and catalysis.