Engineering Ni-N₂O₂ Coordination in Single-Atom Catalysts for Alkaline Hydrogen Evolution

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Single-atom catalysts (SACs) offer high atom utilization efficiency for electrocatalysis.
• Tailoring the coordination environment of metal atoms in SACs is crucial for optimizing catalytic activity.
• Traditional nickel-based SACs often feature Ni-N₄ coordination, limiting their potential.

Purpose of the Study:

• To design and synthesize a novel single-atom catalyst with a unique Ni-N₂O₂ coordination environment.
• To investigate the electrocatalytic performance of the new catalyst for the hydrogen evolution reaction (HER).
• To demonstrate the effectiveness of coordination engineering in enhancing SACs for alkaline water splitting.

Main Methods:

• Coordination engineering strategy to immobilize nickel atoms on nitrogen-doped carbon nanofibers (NCNFs).
• Characterization of the catalyst's structure using single-crystal X-ray diffraction and X-ray absorption spectroscopy.
• Electrochemical testing of the Ni-N₂O₂/NCNFs catalyst for HER in 1.0 M KOH.

Main Results:

• Successfully synthesized a novel Ni-N₂O₂/NCNFs catalyst with atomically dispersed nickel atoms.
• The Ni-N₂O₂ coordination environment was confirmed by advanced characterization techniques.
• The catalyst achieved a low overpotential of 37 mV at 10 mA cm^-2 for HER in alkaline media.

Conclusions:

• The Ni-N₂O₂ coordination configuration significantly enhances HER activity compared to traditional Ni-N₄ sites.
• Coordination engineering is a viable strategy for designing highly efficient and stable SACs.
• This work provides valuable insights for developing advanced catalysts for alkaline water splitting and other electrochemical applications.