Energizing Co Active Sites via d-Band Center Engineering in CeO2-Co3O4 Heterostructures: Interfacial Charge Transfer Enabling Efficient Nitrate Electrosynthesis.

ABSTRACT

The electrochemical nitrogen oxidation reaction (NOR) holds significant potential to revolutionize the traditional nitrate synthesis processes. However, the progression in NOR has been notably stymied due to the sluggish kinetics of initial N2 adsorption and activation processes. Herein, the research embarks on the development of a CeO2-Co3O4 heterostructure, strategically engineered to facilitate the electron transfer from CeO2 to Co3O4. This orchestrated transfer operates to amplify the d-band center of the Co active sites, thereby enhancing N2 adsorption and activation dynamics by strengthening the Co─N bond and diminishing the resilience of the N≡N bond. The synthesized CeO2-Co3O4 manifests promising prospects, showcasing a significant HNO3 yield of 37.96 µg h-1 mgcat -1 and an elevated Faradaic efficiency (FE) of 29.30% in a 0.1 m Na2SO4 solution at 1.81 V versus RHE. Further substantiating these findings, an array of in situ methodologies coupled with DFT calculations vividly illustrate the augmented adsorption and activation of N2 on the surface of CeO2-Co3O4 heterostructure, resulting in a substantial reduction in the energy barrier pertinent to the rate-determining step within the NOR pathway. This research carves a promising pathway to amplify N2 adsorption throughout the electrochemical NOR operations and delineates a blueprint for crafting highly efficient NOR electrocatalysts.