Unidirectional Alignment of AgCN Microwires on Distorted Transition Metal Dichalcogenide Crystals

TL;DR

This study demonstrates the unidirectional alignment of AgCN microwires on distorted transition metal dichalcogenide crystals, revealing symmetry-dependent assembly behavior and potential applications in crystal orientation identification.

Contribution

It provides the first detailed analysis of AgCN microwire assembly on distorted TMDCs, highlighting the role of substrate symmetry in directional alignment and offering new insights into van der Waals epitaxy.

Findings

AgCN microwires align unidirectionally on distorted TMDCs

Alignment correlates with underlying crystal symmetry

Aligned microwires can identify TMDC polymorphs and orientations

Abstract

Van der Waals epitaxy on the surface of two-dimensional (2D) layered crystals has gained significant research interest for the assembly of well-ordered nanostructures and fabrication of vertical heterostructures based on 2D crystals. Although van der Waals epitaxial assembly on the hexagonal phase of transition metal dichalcogenides (TMDCs) has been relatively well characterized, a comparable study on the distorted octahedral phase (1T' or Td) of TMDCs is largely lacking. Here we investigate the assembly behavior of one-dimensional (1D) AgCN microwires on various distorted TMDC crystals, namely 1T'-MoTe2, Td-WTe2, and 1T'-ReS2. The unidirectional alignment of AgCN chains is observed on these crystals, reflecting the symmetry of underlying distorted TMDCs. Polarized Raman spectroscopy and transmission electron microscopy directly confirm that AgCN chains display the remarkable alignment behavior along the distorted chain directions of underlying TMDCs. The observed unidirectional assembly behavior can be attributed to the favorable adsorption configurations of 1D chains along the substrate distortion, which is supported by our theoretical calculations and observation of similar assembly behavior from different cyanide chains. The aligned AgCN microwires can be harnessed as facile markers to identify polymorphs and crystal orientations of TMDCs.