Phase-Selective Synthesis of Mo-Ta-C Ternary Nanosheets by Precisely Tailoring Mo/Ta Atom Ratio on Liquid Copper

Phase-selective synthesis is an effective way to expand the ultra-thin transition metal carbide family and tune its properties. Herein, a chemical vapor deposition route with specially designed substrate (Ta wire-Cu foil-Mo foil) is carried out to synthesize Mo-Ta-C ternary nanosheets with tunable phase structure. The Ta atoms diffuse on the surface of liquid copper and Mo atoms diffuse through the liquid copper to the surface, which react with the carbon atoms decomposed from the methane and form the Mo-Ta-C ternary nanosheets. By precisely tailoring the Mo/Ta ratio and growth temperature, ultrathin layered orthorhombic (Mo_2/3Ta_1/3)₂C nanosheets and non-layered cubic (Mo_0.13Ta_0.87) C nanosheets with thickness of 21 and 4 nm are selectively synthesized. The approach could pave the way for the formation of multi-component carbide nanosheets with controllable phases.