FeOOH regulation on Cu2O/CoO heterointerfaces toward efficient nitrate electroreduction to ammonia

The Cu₂O/CoO/FeOOH heterostructure achieves high Faradaic efficiency and ammonia yield at low applied potential. • Further analysis reveals heterointerface‑tuned electronic structure and accelerated synergistic electron transfer. • The Cu₂O/CoO/FeOOH heterostructure exhibits excellent long‑term durability. Electrochemical nitrate into ammonia is a feasible and promising wastewater recovery strategy. In this work, a ternary Cu 2 O/CoO/FeOOH heterogeneous structure catalyst with rich interface has been reasonably designed. In the complex system, the electron-rich Cu active center enhances the adsorption of nitric acid radical ions, while Co and Fe species promote the generation of reacted hydrogen (H*) intermediates. The synergistic effect between multiple active sites effectively reduces the energy barrier of the eight-electron nitrate reduction reaction. Therefore, the optimized catalyst achieved a high Faradaic efficiency (FE) of 95.75% and a significant NH 3 yield of 9.83 mg h −1 cm −2 under the condition at −0.4 V vs. RHE. This study confirms the key role of interface electronic regulation in improving the electroreduction performance of nitrates, and provides a simple and reliable strategy for the rational design and construction of high-efficiency heterogeneous structural electrocatalysts. Download: Download high-res image (151KB) Download: Download full-size image A rationally designed ternary Cu 2 O/CoO/FeOOH heterostructured catalyst abundant in heterogeneous interfaces is reported, in which electron-enriched Cu sites strengthen nitrate adsorption and Co/Fe species facilitate the formation of reactive H* intermediates; the multi-site synergism substantially lowers the energy barrier for the eight-electron nitrate-to-ammonia reduction.