Non-Precious Metal Catalysts with Gradient Oxidative Dual Sites Boost Bimolecular Activation for Catalytic Oxidation Reactions.

Catalytic oxidation emerges as a highly promising and cost-effective approach for eliminating gaseous pollutants, greenhouse gases, and volatile organic compounds (VOCs) from industrial exhaust streams. However, achieving the simultaneous activation of O2 and substrate molecules at low temperatures using non-precious metal catalysts remains a significant challenge. In this study, we introduce gradient oxidative Cu─O─Ti/Cu─O─Cu dual sites that enhance bimolecular activation for catalytic oxidation reactions. The catalyst, Ti-doped CuO, is synthesized on a TiO2 support through the immobilization of Cu2⁺ on NO3⁻-grafted TiO2, followed by thermal treatment. The resulting gradient oxidative Cu─O─Ti/Cu─O─Cu sites exhibit exceptional catalytic oxidation activity for NH3 and various VOCs at low temperatures, matching the performance of precious metal-based catalysts. Notably, during NH₃ oxidation, Cu─O─Ti sites enhance the activation of both O₂ and NH₃. HNO intermediates formed on Cu─O─Ti sites react with NH intermediates on neighboring Cu─O─Cu sites-producing N₂ and H₂O via an imide mechanism-which effectively lowers the reaction barrier for catalytic NH₃ oxidation. As such, dual sites in non-precious metal catalysts show promising results for advancing future catalytic oxidation technologies.