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

Abstract

AbstractThe 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 mgcat−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 mgcat−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.