Co0 and CoOx Nanoclusters Encapsulated in Carbon Microspheres for the Low‐Temperature Enhanced Reduction of NOx by CO

Abstract Efficient low‐temperature NO reduction by transition metal‐based catalysts remains a significant challenge. In this study, a Co‐based catalyst, Co 0 +CoO x @CS, encapsulated by carbon microspheres and synthesized via a one‐step in situ hydrothermal method, exhibits excellent NO conversion, exceeding 99% at 150 °C. X‐ray Absorption Fine Structure analysis reveals electronic interactions between C and Co, anchoring Co 0 nanoclusters to the carbon microspheres. The resulting microporous structure enhances reactant accessibility and facilitates N─O bond cleavage. Furthermore, C 13 O isotopic tracing experiments reveal that NO reduction follows an ONNO pathway, in which adsorbed CO induces the dissociation of ONNO * to ONN * , and weakly adsorbed or gaseous CO promotes further decomposition of ONN * to N 2 . Specifically, Co 0 species enhance NO adsorption, while CoO x species favor CO adsorption, with oxygen vacancy‐mediated oxygen transfer driving the catalytic cycle. This study presents a novel approach for preparing microporous Co‐based catalysts and offers an effective strategy for efficient low‐temperature NO reduction.