Metal-Support Interaction Triggered Electronic Reconstruction in Pd/CoN-Co₄N Catalysts for Optimizing MEK Oxidation...

The development of noble metal catalysts integrating high activity with strong poisoning resistance remains highly desirable yet challenging. Herein, the metallic electron-donating property of a cobalt nitride support is leveraged to enhance the electron metal-support interaction (EMSI) with Pd, concurrently improving the activity and poisoning resistance of Pd/CoN-Co₄N in methyl ethyl ketone (MEK) oxidation. Over which, 90% of MEK is oxidized at ca. 172 °C by Pd/CoN-Co₄N, versus only 48% conversion over Pd/Co₃O₄. Crucially, Pd/CoN-Co₄N exhibits exceptional resistance to H₂S and 1,2-dichloroethane poisoning, with performance showing almost no degradation upon H₂S exposure, which completely deactivates Pd/Co₃O₄. The strong EMSI induces a profound electronic redistribution, facilitating electron transfer from the support to Pd and generating electron-rich Pd⁰ in situ. This modulates the Pd d-band center toward the Fermi level, enhancing MEK and O₂ adsorption/activation and promoting deep oxidation of carboxylate intermediates. Furthermore, the enhanced EMSI creates abundant Lewis acid sites by modulating the charge density of Co atoms. These sites serve as sacrificial adsorption sites for electron-rich poison molecules, thus shielding the Pd sites and facilitating rapid contaminant desorption. This work provides atomic-level insight into EMSI on non-oxide supports and proposes a design principle for robust catalysts toward environmental purification.