Graphitized Carbon-Supported Co@Co3O4 for Ozone Decomposition over the Entire Humidity Range

Ground-level ozone (O₃) pollution has emerged as a significant concern due to its detrimental effects on human health and the ecosystem. Catalytic removal of O₃ has proven to be the most efficient and cost-effective method. However, its practical application faces substantial challenges, particularly in relation to its effectiveness across the entire humidity range. Herein, we proposed a novel strategy termed "dual active sites" by employing graphitized carbon-loaded core-shell cobalt catalysts (Co@Co₃O₄-C). Co@Co₃O₄-C was synthesized via the pyrolysis of a Co-organic ligand as the precursor. By utilizing this approach, we achieved a nearly constant 100% working efficiency of the Co@Co₃O₄-C catalyst for catalyzing O₃ decomposition across the entire humidity range. Physicochemical characterization coupled with density functional theory calculations elucidates that the presence of encapsulated metallic Co nanoparticles enhances the reactivity of the cobalt oxide capping layer. Additionally, the interface carbon atom, strongly influenced by adjacent metallic Co nuclei, functions as a secondary active site for the decomposition of O₃ decomposition. The utilization of dual active sites effectively mitigates the competitive adsorption of H₂O molecules, thus isolating them for adsorption in the cobalt oxide capping layer. This optimized configuration allows for the decomposition of O₃ without interference from moisture. Furthermore, O₃ decomposition monolithic catalysts were synthesized using a material extrusion-based three-dimensional (3D) printing technology, which demonstrated a low pressure drop and exceptional mechanical strength. This work provides a "dual active site" strategy for the O₃ decomposition reaction, realizing O₃ catalytic decomposition over the entire humidity range.