Single-atom catalysts confined in shell layer achieved by a modified top-down strategy for efficient CO₂ reduction.

Area of Science:

• Materials Science
• Catalysis
• Electrochemistry

Background:

• High-temperature pyrolysis is a common method for synthesizing single-atom catalysts (SACs).
• This method often leads to low atom utilization due to metal atom migration.
• Developing efficient synthesis strategies for SACs is crucial for catalysis.

Purpose of the Study:

• To develop a novel top-down synthesis strategy for high-performance single-atom catalysts.
• To achieve in situ atomization and confinement of single atoms within a support structure.
• To enhance the catalytic performance for CO2 reduction.

Main Methods:

• Surface-sintered nickel sulfide (NiS2) nanoparticles were synthesized.
• A top-down atomization strategy was employed to generate single Ni atoms.
• Electrochemical CO2 reduction was performed in a flow cell.
• Theoretical calculations were used to investigate reaction mechanisms.

Main Results:

• The novel synthesis strategy successfully atomized NiS2 nanoparticles into single Ni atoms confined within the shell layer.
• Single Ni atoms were predominantly distributed on the support surface, enhancing active site accessibility.
• Theoretical calculations revealed that S atoms in the second coordination shell reduce CO2 reduction activation energy.
• The Ni single-atom catalyst achieved nearly 100% Faradaic efficiency for CO (FE_CO) over a wide potential range (-0.5 to -1.3 V vs. RHE).
• A maximum partial current density for CO of 709 mA cm-2 was achieved at -1.6 V vs. RHE.

Conclusions:

• The developed top-down synthesis strategy offers a promising route for producing highly efficient single-atom catalysts.
• The confinement and surface distribution of single Ni atoms significantly improve catalytic performance.
• The presence of S atoms plays a crucial role in enhancing the CO2 reduction reaction kinetics.