Versatile Synthesis of Low-Dimensional Te-Based Nanomaterials and Thickness-Tailored Functionalities of Two-Dimensional Cu2Te Flakes for High-Performance Devices

Low-dimensional Te-based materials exhibited unique and fascinating properties for next-generation electronics. This work presented a versatile vapor-phase strategy for selectively growing diverse Te-based nanomaterials (Te, GaTe, Cu 2 Te) by Te-source designs, with an emphasis on thickness-controlled synthesis and properties of 2D Cu 2 Te flakes. Key to this approach involves molten Te encapsulation to stabilize GaTe for 2D growth and a unique Te sustained-release mechanism via controlled GaTe oxidation, which enabled epitaxial growth of Te nanoribbons and well-aligned Cu 2 Te assisted by complementary Cu foil and forming a Cu-Te alloy. The obtained high-quality 2D Cu 2 Te featured a non-centrosymmetric hexagonal Nowotny phase with pronounced in-plane anisotropic second-harmonic generation signals. Critically, layer thickness as a powerful intrinsic non-volatile parameter for property engineering was further demonstrated. Electrocatalytic hydrogen evolution activity of 2D Cu 2 Te improved systematically with thickness owing to Fermi level upshifts. In contrast, the rectification behavior of the fabricated type-I p-Cu 2 Te/n-MoS 2 heterostructure diodes showed a strong and non-monotonic Cu 2 Te thickness dependence, achieving a high rectification ratio of 1.1 × 10 3 at an optimal 27.0 nm through tailored carrier concentration and interfacial band engineering. Our study provides both flexible synthesis platforms and fundamental insights into thickness-driven functionality, opening new avenues for constructing high-performance electronic and energy devices.