Self-supporting electrode incorporating active Co sites for ultrafast ammonia production from nitrate reduction

Electrocatalytic nitrate (NO 3 − ) reduction reaction (NitRR) provides us a green solution to synthesize ammonia (NH 3 ) and ease environmental problems. However, the development of robust electrodes with high NH 3 yield rates and Faradaic efficiencies (FEs) is still challenging. Herein, we report a self-supporting electrode incorporating vertically aligned Co-based metal-organic framework (MOF) nanosheets (Co-NDC/NF), which facilitates electron and mass transfer for efficient NitRR to NH 3 within a wide range of NO 3 − concentration (0.05−1.0 M). In 1.0 M KOH + 1.0 M KNO 3 electrolytes, such Co-NDC/NF reaches a notable NH 3 yield rate of 19,200 ug h −1 cm −2 , a high FE of 93.9% and excellent electrochemical stability, which is superior to most electrocatalysts. A flow-through reactor with large-area Co-NDC/NF also achieves the continuous production of 1096 mg L −1 NH 3 under an industrial current density. Furthermore, the rapid transformation of *NO 2 − to *NO and selective conversion of *NO to *NOH played critical roles in NitRR toward ultrafast NH 3 production. Our research not only offers a facile fabrication procedure for high-performance electrode, but also gives new insights into the enhanced electron transfer and mass transport within MOF-based electrode in electrochemical reactions.