Versatile Synthesis of Low‐Dimensional Te‐Based Nanomaterials and Thickness‐Tailored Functionalities of Two‐Dimensional Cu 2 Te Flakes for High‐Performance Devices

ABSTRACT 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.