3d transition metal coordination on monolayer MoS₂: a facile doping method to functionalize surfaces

Area of Science:

• Materials Science
• Surface Chemistry
• Condensed Matter Physics

Background:

• Two-dimensional materials (2DMs) possess unique properties tunable via doping and surface functionalization.
• Single-atom functionalization offers a novel route to modify 2DM properties.

Purpose of the Study:

• To investigate the coordination reaction between MoS2 monolayers and 3d transition metals (TMs).
• To understand the nature of MoS2-TM interactions and their impact on material properties.

Main Methods:

• Density functional theory (DFT) calculations.
• X-ray photoelectron spectroscopy (XPS) for chemical state and charge transfer analysis.
• Photoluminescence (PL) spectroscopy for electronic property evaluation.

Main Results:

• Formation of MoS2-TM coordination complexes observed.
• Adsorption energies correlate with crystal-field stabilization energies.
• Pearson's hard-soft acid-base and ligand-field theories explain bonding trends (covalent vs. ionic).
• Ni functionalization induces n-type doping, while Cu results in p-type doping.

Conclusions:

• Coordination complex formation is an effective strategy for defect-free tuning of MoS2 monolayer properties.
• Understanding TM coordination provides insights into single-atom functionalization mechanisms.
• This approach offers precise control over electronic properties through targeted doping.