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

Abstract The electrochemical N 2 oxidation reaction (NOR) has emerged as a promising approach for achieving high selectivity in nitric acid (HNO 3 ) production. However, the sluggish N 2 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 Co 3 O 4 (Ce–Co 3 O 4 ) is proposed. The Ce–Co 3 O 4 catalyst exhibits an enhanced HNO 3 yield of 24.76 µg h −1 mg cat −1 and a promoted Faradaic efficiency of 31.93% in 0.1 m Na 2 SO 4 electrolyte under ambient conditions compared to those of the pure Co 3 O 4 (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–Co 3 O 4 . 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 N 2 activation on the surface of Ce–Co 3 O 4 . This work provides a promising route for the preparation of efficient NOR catalysts and sheds light on the mechanism of N 2 activation through orbital hybridization.