Substrate Engineering toward Selective Growth of Ultrathin WC Crystals and Heterostructures via Liquid Cu-Zn Catalyst

Transition metal carbides (TMCs) grown by chemical vapor deposition (CVD) offer promise for numerous novel phenomena and applications in the 2D limit. Despite considerable efforts thus far, the flexible customization of TMCs and their heterostructures still remains challenging. Herein, a substrate engineering is developed to achieve customized manufacturing of ultrathin WC single crystals and WC/graphene (WC-G) heterostructures by varying the concentration of Zn in Cu-Zn alloy substrate. It is worth noting that Zn atoms can remarkably reduce the nucleation density of graphene and promote the nucleation of WC. Thus, an increasing Zn content is applied to synergistically modulate the growth of graphene and WC, enabling the controllable fabrication of WC and WC-G heterostructures. The synthesized WC crystals exhibit an ultrathin nature down to 3 nm, as well as high crystalline, ultra-clean surface, and superb chemical stability. Based on that, the typical metallic properties with a temperature-dependent resistance (nearly 1.30 omega at 300 K and nearly 0.08 omega at 1.7 K) and low resistance as well as excellent nonlinear optical performance of WC are demonstrated. This work provides fresh insights into regulating the growth behavior of multiblock-structured carbides and promotes the study of their optic and electronic properties. Dynamic regulation and customized manufacturing of WC single crystal and WC/graphene (WC-G) heterostructure can be achieved through a substrate engineering of Cu-Zn alloys. The composition of alloys can be adjusted by varying the ratio of Cu and Zn, wherein low Zn concentration contribute to the growth of WC-G heterostructure and high Zn concentration result in the formation of WC. image