Proximity effects in graphene-supported single-atom catalysts for hydrogen evolution reaction

Area of Science:

• Catalysis
• Materials Science
• Physical Chemistry

Background:

• The efficiency and atom utilization in single-atom catalysts depend on interactions between adjacent active sites.
• Understanding these interactions is key to designing high-performance catalysts.

Purpose of the Study:

• To investigate the catalytic activity of hydrogen evolution reaction (HER) based on the distance between nitrogen-coordinated transition metal centers in graphene.
• To explore the proximity effect on single-atom catalyst reactivity.

Main Methods:

• Density functional theory (DFT) calculations were employed to study the HER activity at varying site distances.
• Electronic properties and net charge of active sites were analyzed to understand the proximity effect.

Main Results:

• A proximity effect was observed in Co-series single-atom catalysts, influencing reactivity with site spacing.
• Optimal distances for Co, Rh, and Ir active sites were determined to be approximately 0.8 nm and 2.8 nm, respectively.
• The proximity effect is attributed to the net charge of the active site and an electron nodal channel facilitating communication.

Conclusions:

• The study reveals that the proximity effect in single-atom catalysts is governed by electronic properties and inter-site communication.
• An optimal Fe-N2C2 structure was designed, demonstrating a significant proximity effect.
• This work presents a simple and effective strategy for tuning single-atom catalyst reactivity through controlled site spacing.