In Situ Elucidations of the Mechanism for Inert Molecular N ₂ O Decomposition at Low Temperature Catalyzed by High‐Index Interfacial Exposed Co ₃ O ₄

ABSTRACT Co ₃ O ₄ has emerged as a promising catalyst for decomposition of greenhouse gas N ₂ O ( de N ₂ O). And the catalytic performance can be significantly influenced by the different exposed crystalline facets, with multiple high‐index facets garnering attention because of their superior activity. However, challenges persist in the synthesis of high‐index facets and in fully understanding their catalytic mechanisms. This work introduces a straightforward method for synthesizing multi high‐index crystal facet catalysts and establishes the mechanism of low‐temperature de N ₂ O catalysis through in situ experiments and theoretical calculations. Compared to commonly synthesized Co ₃ O ₄ with the (110) facet exposed, the as‐synthesized Co ₃ O ₄ with the interfacial facet (400−400), performs nearly 8 times higher on de N ₂ O efficiency at 300°C. Experimental results and density functional theory calculations demonstrate that Co ³⁺ on (400−400) can form a novel active Co ³⁺ ‐O ^* motif during the de N ₂ O reaction, which exhibits a unique electronic structure and offers an alternative route for de N ₂ O, effectively shortening the reaction steps and enhancing overall efficiency. This work establishes an essential theoretical foundation for the development of catalysts capable of activating inert molecules at low temperatures, thereby enabling their activation and utilization.