Boosting N₂O Decomposition by Fabricating the Cs–O–Co Structure over Co₃O₄ with Single-Layer Atoms of Cs

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Developing effective catalysts for N₂O decomposition at low temperatures is challenging. Herein, the Cs-O-Co structure, as the active species fabricated by single-layer atoms of Cs over pure Co₃O₄, originally exhibited great catalytic activity of N₂O decomposition in simulated vehicle exhaust and flue gas from nitric acid plants. A similar catalytic performance was also observed for Na, K, and Rb alkali metals over Co₃O₄ catalysts for N₂O decomposition, illustrating the prevalence of alkali-metal-promotion over Co₃O₄ in practical applications. The catalytic results indicated that the TOF of Co₃O₄ catalysts loaded by 4 wt% Cs was nearly 2 orders of magnitude higher than that of pure Co₃O₄ catalysts at 300 °C. Interestingly, the conversions of N₂O decomposition over Co₃O₄ catalysts doped by the same Cs loadings were significantly inhibited. Characterization results indicated that the primary active Cs-O-Co structure was formed by highly orbital hybridization between the Cs 6s and the O 2p orbital over the supported Co₃O₄ catalysts, where Cs could donate electrons to Co³⁺ and produce much more Co²⁺. In contrast, the doped Co₃O₄ catalysts were dominated by Cs₂O₂ species; meanwhile, CsOH species was generated by adsorbed water vapor led to a significant decrease in catalytic activity. In situ DRIFTS, rigorous kinetics, and DFT results elaborated the reaction mechanism of N₂O decomposition, where the direct decomposition of adsorbed N₂O was the kinetically relevant step over supported catalysts in the absence of O₂. Meanwhile, the assistance of adsorbed N₂O decomposition by activated oxygen was observed as the kinetically relevant step in the presence of O₂. The results may pave a promising path toward developing alkali-metal-promotion catalysts for efficient N₂O decomposition.