Metal-organic framework-confined Co₃O₄ for humidity-immune ozone decomposition

Ground-level ozone (O₃) is a major air pollutant, and catalytic decomposition represents a promising strategy for its removal. However, maintaining high catalytic efficiency under humid conditions remains a considerable challenge. In this study, we encapsulate ultrafine metal oxides (UMOs; e.g., Co₃O₄, NiO) within the nanopores of an Fe₃O-cluster-based metal-organic framework, PCN-333(Fe), for catalytic O₃ decomposition. The optimized 30% Co₃O₄@PCN-333(Fe) catalyst achieves sustained 100% O₃ conversion for over 120 hours in a continuous airflow containing 40 ppm O₃ under high space velocity (1.75 × 10⁵h^-1) and a broad range of humidity (10-90% RH). Mechanistic investigations reveal that the exceptional performance originates from an interfacial hydrogen-atom transfer process between Co₃O₄ and the Fe₃O clusters of PCN-333(Fe), as confirmed by in situ diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS) and in situ Raman spectroscopy. This work proposes a general principle for designing humidity-immune catalytic interfaces between metal oxides and porous materials, thereby providing a practical foundation for sustainable control of pollutant emissions in complex environments.