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.