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

Nitrate electroreduction reaction (eNO3‐RR) to ammonia (NH3) 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 eNO3‐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 eNO3‐RR setup provided superior NH3 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 NH3 FE of 85.4%, outperforming the state‐of‐the‐art eNO3‐RR catalysts. Coupled with the COMSOL multiphysics simulations and in‐situ infrared spectroscopy, the main contributor for the high‐efficiency NH3 production could be the steady fluid field to timely rejuvenate the electrocatalyst surface during the electrocatalysis.