Two‐dimensional Cu Plates with Steady Fluid Fields for High‐rate Nitrate Electroreduction to Ammonia and Efficient Zn‐Nitrate Batteries

Nitrate electroreduction reaction (eNO 3 − RR) to ammonia (NH 3 ) provides a promising strategy for nitrogen utilization, while achieving high selectivity and durability at an industrial scale has remained challenging. Herein, we demonstrated that the performance of eNO 3 − RR could be significantly boosted by introducing two‐dimensional Cu plates as electrocatalysts and eliminating the general carrier gas to construct a steady fluid field. The developed eNO 3 − RR setup provided superior NH 3 Faradaic efficiency (FE) of 99 %, exceptional long‐term electrolysis for 120 h at 200 mA cm −2 , and a record‐high yield rate of 3.14 mmol cm −2 h −1 . Furthermore, the proposed strategy was successfully extended to the Zn‐nitrate battery system, providing a power density of 12.09 mW cm −2 and NH 3 FE of 85.4 %, outperforming the state‐of‐the‐art eNO 3 − RR catalysts. Coupled with the COMSOL multiphysics simulations and in situ infrared spectroscopy, the main contributor for the high‐efficiency NH 3 production could be the steady fluid field to timely rejuvenate the electrocatalyst surface during the electrocatalysis.