Phase-Engineered WS₂ Monolayer Quantum Dots by Rhenium Doping

Area of Science:

• Materials Science
• Nanotechnology
• Catalysis

Background:

• Transition metal dichalcogenides (TMDs) exist in stable (2H) and metastable (1T) phases.
• Phase engineering of TMDs is crucial for energy storage and electrocatalysis.
• Controlling TMD phase transitions and synthesis remains a challenge.

Purpose of the Study:

• To synthesize Re-doped WS₂ monolayer quantum dots (MQDs) with controlled phase.
• To investigate the mechanism of Re-induced phase transitions in WS₂.
• To evaluate the catalytic performance of phase-engineered WS₂ MQDs for hydrogen evolution reaction.

Main Methods:

• Colloidal chemical synthesis of Re-doped WS₂ MQDs.
• Systematic variation of Re doping concentration.
• Characterization using scanning transmission electron microscopy (STEM).

Main Results:

• Re doping induces strain in the 2H phase (S2H), transitioning to 1T and 1T' phases with increasing Re concentration.
• Controlled experiments with MoS₂ doping confirmed Re's role in phase engineering.
• 1T' WS₂ MQDs with 49 at.% Re exhibited superior hydrogen evolution reaction (HER) performance.

Conclusions:

• Re doping provides a viable route for phase engineering of TMDs like WS₂ and MoS₂.
• The study elucidates the mechanism of Re-induced phase transitions.
• Phase-engineered 1T' WS₂ MQDs show significant potential for efficient HER catalysis.