Sulfur-Engineered Second-Shell in Fe-N₄ Catalysts: Dual Active Sites Harmonized Activity and Stability in Real Water...

Area of Science:

• Materials Science
• Environmental Chemistry
• Catalysis

Background:

• Single-atom catalysts (SACs) offer high activity but suffer from instability and inactivation in complex environments.
• The role of nonmetal dopants, particularly in the second coordination shell, is underexplored for SACs.
• Existing methods focus on the metal coordination environment, neglecting broader dopant effects.

Purpose of the Study:

• To develop stable single-atom catalysts (SACs) for complex environmental applications.
• To investigate the dual functionality of second-shell nonmetal dopants in SACs.
• To establish a versatile design platform for robust SACs.

Main Methods:

• Synthesis of S-engineered second-shell Fe single-atom catalysts (FeNSC).
• Investigation of a dual-site catalytic mechanism involving both Fe centers and S dopants.
• Electrochemical performance testing for Pb(II) and Cd(II) detection in real water samples.

Main Results:

• FeNSC demonstrated enhanced stability and maintained atomically dispersed single-atom sites.
• A dual-site mechanism was confirmed, with S sites catalyzing Cd(II) and Fe centers targeting Pb(II).
• Exceptional electrocatalytic performance achieved for Pb(II) and Cd(II) detection in complex water matrices, outperforming previous catalysts.

Conclusions:

• Second-shell S dopants provide dual functionality as active sites and stabilizers for SACs.
• The developed FeNSC exhibits high sensitivity and resistance to interfering ions in real-world samples.
• This work presents a promising design strategy for stable SACs in challenging environmental applications.