| Popis: |
The quest to make free-standing monolayer gold has hitherto been limited to free-standing several-atoms-thick layers, or monolayers but confined on or inside another template. Examples are monolayers diffused into double hydroxides1, membranes framed in alloys under electron irradiation2, nano-ribbons suspended in graphene3, quantum dots on hexagonal BN4, monolayers in between SiC wafers and monolayer graphene5, and fragments produced via thermal dewetting on sapphire6. Here, we report the synthesis of free-standing single-atom-thick 2D gold (named goldene) by wet-chemically etching away Ti3C2 from Ti3AuC2, a nano-laminated MAX-phase ceramic initially formed by substituting Si in Ti3SiC2 with Au7. The free-standing goldene layers are revealed by scanning transmission electron microscopy. While ab initio molecular dynamics simulations show that 2D goldene is inherently stable, the experiments reveal a tendency for curling and agglomeration at edges. Prospects for preparing goldene from a series of non-van der Waals Au-intercalated MAX-phases, including developing etching schemes, are also presented. |
