Controlled Synthesis of Submillimeter Non-layered WO 2 Nanoplates via a WSe 2 -Assisted Method.

Two-dimensional metal oxides (2DMOs) have stimulated tremendous attention due to their distinct electronic structures and abundant surface chemistry. However, it remains a standing challenge for the synthesis of 2DMOs because of their intrinsic 3D lattice structure and ultrahigh synthesis temperature. Here, a reliable WSe 2 -assisted chemical vapor deposition (CVD) strategy to grow high-quality and non-layered WO 2 nanoplates with tunable thickness and lateral dimension is reported. Optical microscopy (OM) and scanning electron microscopy (SEM) studies demonstrate that WO 2 nanoplates exhibit a well-faceted rhombic geometry with a lateral dimension up to the submillimeter level (∼135 μm), which is the largest size of 2D metal oxide single crystals obtained by CVD to date. Raman spectroscopy and scanning transmission electron microscopy (STEM) studies reveal that the nanoplates are high-quality single crystals with a monoclinic WO 2 crystal structure. Electrical measurements show the nanoplates exhibit metallic behavior with strong anisotropic resistance, outstanding conductivity of 1.1×10 6 S m -1 , and breakdown current density of 7.1 × 10 7 A cm -2 . More interestingly, low-temperature magnetotransport studies demonstrate that the nanoplates show the quantum-interference-induced weak localization effect. The developed WSe 2 -assisted strategy for the growth of WO 2 nanoplates could enrich the library of 2D metal oxide materials and provide a material platform for other property explorations based on 2D WO 2 . This article is protected by copyright. All rights reserved.