Optimization of Carbon‐Defect Engineering to Boost Catalytic Ozonation Efficiency of Single Fe─N₄ Coordination Motif

AbstractCarbon‐defect engineering in single‐atom metal‐nitrogen‐carbon (M─N─C) catalysts by straightforward and robust strategy, enhancing their catalytic activity for volatile organic compounds, and uncovering the carbon vacancy‐catalytic activity relationship are meaningful but challenging. In this study, an iron‐nitrogen‐carbon (Fe─N─C) catalyst is intentionally designed through a carbon‐thermal‐diffusion strategy, exposing extensively the carbon‐defective Fe─N4 sites within a micro‐mesoporous carbon matrix. The optimization of Fe─N4 sites results in exceptional catalytic ozonation efficiency, surpassing that of intact Fe─N4 sites and commercial MnO2 by 10 and 312 times, respectively. Theoretical calculations and experimental data demonstrated that carbon‐defect engineering induces selective cleavage of C─N bond neighboring the Fe─N4 motif. This induces an increase in non‐uniform charges and Fermi density, leading to elevated energy levels at the center of Fe d‐band. Compared to the intact atomic configuration, carbon‐defective Fe─N4 site is more activated to strengthen the interaction with O3 and weaken the O─O bond, thereby reducing the barriers for highly active surface atomic oxygen (*O/*OO), ultimately achieving efficient oxidation of CH3SH and its intermediates. This research not only offers a viable approach to enhance the catalytic ozonation activity of M─N─C but also advances the fundamental comprehension of how periphery carbon environment influences the characteristics and efficacy of M─N4 sites.