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

Abstract

Developing effective catalysts for N 2 O 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 Co 3 O 4, originally exhibited great catalytic activity of N 2 O 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 Co 3 O 4 catalysts for N 2 O decomposition, illustrating the prevalence of alkali-metal-promotion over Co 3 O 4 in practical applications. The catalytic results indicated that the TOF of Co 3 O 4 catalysts loaded by 4 wt% Cs was nearly 2 orders of magnitude higher than that of pure Co 3 O 4 catalysts at 300 °C. Interestingly, the conversions of N 2 O decomposition over Co 3 O 4 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 Co 3 O 4 catalysts, where Cs could donate electrons to Co 3+ and produce much more Co 2+ . In contrast, the doped Co 3 O 4 catalysts were dominated by Cs 2 O 2 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 N 2 O decomposition, where the direct decomposition of adsorbed N 2 O was the kinetically relevant step over supported catalysts in the absence of O 2 . Meanwhile, the assistance of adsorbed N 2 O decomposition by activated oxygen was observed as the kinetically relevant step in the presence of O 2 . The results may pave a promising path toward developing alkali-metal-promotion catalysts for efficient N 2 O decomposition.

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