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摘要
Carbon-defect engineering in single-atom metal-nitrogen-carbon (M & horbar;N & horbar;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 & horbar;N & horbar;C) catalyst is intentionally designed through a carbon-thermal-diffusion strategy, exposing extensively the carbon-defective Fe & horbar;N-4 sites within a micro-mesoporous carbon matrix. The optimization of Fe & horbar;N-4 sites results in exceptional catalytic ozonation efficiency, surpassing that of intact Fe & horbar;N-4 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 & horbar;N bond neighboring the Fe & horbar;N-4 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 & horbar;N-4 site is more activated to strengthen the interaction with O-3 and weaken the O & horbar;O bond, thereby reducing the barriers for highly active surface atomic oxygen (*OOO), 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 & horbar;N & horbar;C but also advances the fundamental comprehension of how periphery carbon environment influences the characteristics and efficacy of M & horbar;N-4 sites.
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