Unveiling intrinsic active sites and pivotal intermediate species in N2O decomposition over Co3O4-based catalysts

Abstract

Identifying active sites and reaction intermediates in N₂O decomposition remains a key challenge for spinel-based catalysts. Here, we developed Cu-doped Co₃O₄ catalysts with remarkable N₂O decomposition performance by precisely tuning their surface composition and redox properties. Through a combined experimental and theoretical approach, we identified the “⊡-Co²⁺” pair, comprising a Co²⁺ cation and an adjacent oxygen vacancy (⊡), as the intrinsic active site driving the catalytic process. Crucially, in situ DRIFTS provided the first direct evidence of trans-N₂O₂⁻ as a pivotal reaction intermediate, representing a significant breakthrough in understanding the catalytic mechanism. Based on these insights, we propose a detailed pathway where N₂O adsorbs and dissociates on the Co²⁺ site, while dissociated oxygen undergoes spillover to the vacancy, facilitating the formation of trans-N₂O₂⁻ and driving the catalytic cycle to completion. This unprecedented discovery clarifies the structure–activity relationship in spinel oxides and provides a robust foundation for designing advanced catalysts for N₂O abatement and beyond.