Boosted N₂ Activation through 4f–2p–3d Orbital Hybridization for Efficient Nitrate Electrosynthesis

Abstract The electrochemical N₂ oxidation reaction (NOR) has emerged as a promising approach for achieving high selectivity in nitric acid (HNO₃) production. However, the sluggish N₂ activation process in NOR due to the high cleavage energy barrier of the N≡N bond remains a challenge. Herein, a novel orbital hybridization strategy for tuning the NOR performance through the construction of cerium (Ce) 4f–O 2p–Co 3d network in Ce‐doped Co₃O₄ (Ce–Co₃O₄) is proposed. The Ce–Co₃O₄ catalyst exhibits an enhanced HNO₃ yield of 24.76 µg h⁻¹ mg_cat⁻¹ and a promoted Faradaic efficiency of 31.93% in 0.1 m Na₂SO₄ electrolyte under ambient conditions compared to those of the pure Co₃O₄ (13.75 µg h⁻¹ mg_cat⁻¹ and 23.43%). Density functional theory caculations demonstrate the strong 4f–2p–3d orbital hybridization and electron transfer in Ce–Co₃O₄. Moreover, a series of in situ techniques provide direct evidence of stronger adsorption peaks for Co─N bond and the key intermediate *NO formed after N₂ activation on the surface of Ce–Co₃O₄. This work provides a promising route for the preparation of efficient NOR catalysts and sheds light on the mechanism of N₂ activation through orbital hybridization.