Atomically Dispersed Silver Atoms Embedded in NiCo Layer Double Hydroxide Boost Oxygen Evolution Reaction.

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Bimetallic layered double hydroxides (LDHs) are effective electrocatalysts for the oxygen evolution reaction (OER) in alkaline environments.
• Nickel-cobalt (NiCo) LDH exhibits good stability but lower OER activity compared to other LDHs like NiFe and CoFe LDH.

Purpose of the Study:

• To develop a highly active and stable NiCo LDH electrocatalyst for the anodic OER.
• To investigate the role of single-atom silver modification on NiCo LDH performance.

Main Methods:

• Fabrication of a novel electrocatalyst: single-atom silver grown on NiCo LDH supported by carbon cloth (Ag_SA -NiCo LDH/CC).
• Electrochemical characterization to evaluate OER activity and stability in 1.0 M KOH.
• In situ Raman spectroscopy to identify active species.
• Hard X-ray absorption spectroscopy (XAS) and density functional theory (DFT) calculations to understand the mechanism.

Main Results:

• The Ag_SA -NiCo LDH/CC catalyst achieved a low overpotential of 192 mV at 10 mA cm^-2, significantly improving upon NiCo LDH/CC (410 mV).
• The catalyst demonstrated remarkable stability, maintaining high activity for 500 hours at 100 mA cm^-2.
• In situ studies revealed that in situ formed NiCoOOH is the true active species.
• XAS and DFT calculations confirmed that single-atom silver at Ni sites enhances Ni valence and weakens intermediate adsorption, boosting OER performance.

Conclusions:

• Single-atom silver modification is a highly effective strategy to enhance the OER activity and stability of NiCo LDH electrocatalysts.
• The enhanced performance is attributed to the electronic modulation of Ni sites by single-atom silver, optimizing the adsorption of reaction intermediates.
• The findings provide valuable insights into designing advanced electrocatalysts for efficient oxygen evolution reactions.