Seed-Assisted Substitutional Doping of the Late 3d-Transition Metals in Transition Metal Dichalcogenides

Substitutional doping is essential for tuning the physicochemical properties of 2D transition metal dichalcogenides (TMDs), enabling applications in electronics and catalysis. While early transition metals (TMs) such as Nb and V can be readily incorporated into TMDs lattices, doping with the late 3d TMs such as Ni, Cu, and Zn remains challenging due to their high doping formation energies and low thermodynamic solubility. Here, we present a seed-assisted doping strategy in which Nb serves as an early TM seed dopant to facilitate the incorporation of late 3d TMs during chemical vapor deposition growth. The introduction of Nb seeds significantly enhances doping efficiency in WS₂, achieving concentrations up to 4.3 at. % for Ni, 3.4 at. % for Cu, and 1.3 at. % for Zn. These values significantly exceed the doping levels achieved without seed dopants. First-principles calculations reveal that Nb induces sulfur vacancy formation, thereby lowering the doping formation energies for Ni, Cu, and Zn. Furthermore, the doped WS₂ exhibits enhanced catalytic performance in the hydrogen evolution reaction. This seed-assisted approach provides a scalable and effective platform for late 3d TM doping in TMDs, including MoS₂, expanding their compositional tunability and enabling new functionalities for electronic and catalytic applications.