Sulfur-doping gradient modulates spin-orbital engineering in cobalt single-atom catalysts: Optimized d-p orbital...

Area of Science:

• Environmental Chemistry
• Materials Science
• Catalysis

Background:

• Rational design of single-atom catalysts (SACs) is crucial for peroxymonosulfate-based advanced oxidation processes (PMS-AOPs).
• Understanding the relationship between coordination environment, electronic configuration, and catalytic function in SACs is limited.

Purpose of the Study:

• To engineer SACs with tuned electronic configurations using a sulfur-gradient doping strategy.
• To investigate the impact of coordination geometry and electronic states on PMS activation for sulfadiazine degradation.

Main Methods:

• Developed a series of Co-SxN4-x (x = 0, 1, 2, 3) single-atom catalysts via sulfur-gradient doping.
• Employed multiscale characterization techniques and theoretical analyses to study catalyst structure and electronic properties.
• Evaluated catalytic activity in peroxymonosulfate-activated sulfadiazine degradation and elucidated reaction mechanisms.

Main Results:

• Sulfur doping induced a structural transition from planar to distorted tetrahedral coordination, altering cobalt's spin state.
• The intermediate-spin Co-S1N3 configuration exhibited a volcano-type activity trend, achieving superior catalytic performance.
• Optimized Co 3d-O 2p orbital hybridization and σ-bond adsorption strength facilitated electron transfer kinetics.

Conclusions:

• Established a 'spin-orbital' activity framework for designing efficient SACs.
• Sulfur-gradient engineering synergistically modulates spin states and orbital hybridization for high-performance catalysis.
• Provides a universal paradigm for developing SACs for sustainable water remediation.