Improved high-current-density hydrogen evolution reaction kinetics on single-atom Co embedded in an order...

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Single-atom catalysis offers precisely defined active sites for heterogeneous reactions.
• Developing efficient catalysts for the hydrogen evolution reaction (HER) is crucial for industrial applications.
• High-current-density electrolyzers require catalysts with high active-site density and enhanced mass transfer.

Purpose of the Study:

• To design and evaluate single-atom metal embedded in nitrogen assembly carbon (NAC) catalysts for industrially applicable HER.
• To investigate the potential of Co-NAC catalysts for high-performance hydrogen production.

Main Methods:

• Synthesis of single-atom metal embedded in nitrogen assembly carbon (NAC) catalysts.
• Electrochemical evaluation of catalysts for the hydrogen evolution reaction (HER).
• Density functional theory (DFT) calculations to understand catalytic mechanisms.

Main Results:

• The best-performing Co-NAC catalyst achieved a HER overpotential of 310 mV at a current density of 200 mA cm⁻², relevant for industrial applications.
• DFT calculations indicated favorable hydrogen binding on single-atom cobalt sites, explaining the high HER activity.
• Co-NAC demonstrated robust performance, maintaining activity at 50 mA cm⁻² for 20 h (H-cell) and 150 mA cm⁻² for 100 h (flow cell) under alkaline conditions.

Conclusions:

• Single-atom metal embedded in nitrogen assembly carbon (NAC) catalysts show promise for industrially relevant hydrogen evolution reactions.
• Co-NAC catalysts exhibit high activity, density, and stability, making them suitable for efficient hydrogen production.
• The findings pave the way for practical applications of single-atom catalysis in electrochemical energy conversion.