2H-MoS₂ on Mo₂CT MXene Nanohybrid for Efficient and Durable Electrocatalytic Hydrogen Evolution

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Developing efficient, durable, and earth-abundant hydrogen evolution reaction (HER) catalysts is vital for the hydrogen economy.
• Two-dimensional (2D) MXenes, specifically Mo2CTx, show promise as HER catalysts but suffer from oxidative instability.
• This instability limits their practical application in aqueous electrolytes and air.

Purpose of the Study:

• To develop a scalable method to enhance the stability and catalytic activity of Mo2CTx MXenes for HER.
• To create a Mo2CTx/2H-MoS2 nanohybrid via in situ sulfidation to overcome oxidative degradation.
• To investigate the structure-activity relationship and durability of the novel nanohybrid catalyst.

Main Methods:

• In situ sulfidation of Mo2CTx MXenes to form Mo2CTx/2H-MoS2 nanohybrids.
• Electrochemical characterization of HER activity, including overpotential measurements for specific current densities.
• Density functional theory (DFT) calculations to understand interfacial interactions and electronic properties.
• Long-term stability testing under continuous electrolysis and cyclic voltammetry.

Main Results:

• The Mo2CTx/2H-MoS2 nanohybrid exhibited superior HER activity, achieving -10 mA cm-2geom at 119 mV and -100 mA cm-2geom at 182 mV overpotential.
• DFT calculations confirmed strong interfacial adhesion within the nanohybrid, crucial for enhanced performance.
• The nanohybrid demonstrated remarkable stability, sustaining over -450 mA cm-2geom and showing <30 mV overpotential degradation after 10 days of electrolysis or 100,000 CV cycles.

Conclusions:

• In situ sulfidation is an effective strategy to stabilize Mo2CTx MXenes and create highly active HER catalysts.
• The Mo2CTx/2H-MoS2 nanohybrid offers excellent catalytic performance and unprecedented durability, surpassing pristine MXenes.
• This work represents a significant advancement in utilizing MXenes as noble metal-free catalysts for water splitting and energy conversion applications.