High phase-purity 1T'-MoS₂- and 1T'-MoSe₂-layered crystals

Area of Science:

• Materials Science
• Inorganic Chemistry
• Nanotechnology
• Electrochemistry

Background:

• Phase control is critical for tuning inorganic material properties like conductivity and stability.
• Metallic-phase group-VI transition metal dichalcogenides (e.g., MoS₂, MoSe₂) offer superior electrocatalytic performance compared to their semiconducting forms.
• Synthesizing phase-pure metallic dichalcogenides, particularly in bulk, remains a significant challenge.

Purpose of the Study:

• To achieve large-scale, high-purity synthesis of micrometre-sized metallic-phase 1T'-MoX₂ (X = S, Se) layered bulk crystals.
• To characterize the structure of the synthesized 1T'-MoX₂.
• To evaluate the electrocatalytic activity of 1T'-MoX₂ for the hydrogen evolution reaction (HER).

Main Methods:

• Developed a novel synthesis route for large-scale preparation of 1T'-MoX₂ layered bulk crystals.
• Utilized X-ray diffraction and other characterization techniques to confirm phase purity and crystal structure.
• Performed electrochemical measurements, specifically the hydrogen evolution reaction in acidic media, to assess catalytic activity.

Main Results:

• Successfully synthesized micrometre-sized, high-purity metallic-phase 1T'-MoS₂ and 1T'-MoSe₂ layered bulk crystals.
• Confirmed the distorted octahedral coordination structure of 1T'-MoS₂.
• Demonstrated that the basal plane of 1T'-MoS₂ exhibits significantly higher activity for the electrocatalytic hydrogen evolution reaction than the 2H-MoS₂ phase.

Conclusions:

• Established a viable method for the scalable production of metallic-phase MoX₂ materials.
• The metallic 1T'-phase MoX₂ shows promise as an efficient electrocatalyst for hydrogen production.
• Highlights the importance of phase control in designing advanced materials for energy applications.