Achieving Synchronization of Electrochemical Production of Ammonia from Nitrate and Ammonia Capture by Constructing a “Two‐In‐One” Flow Cell Electrolyzer

Abstract The electrochemical nitrate reduction reaction (NO₃⁻RR) provides a promising route to produce ammonia (NH₃) while addressing environmental issues of NO₃⁻. Although great success has been achieved on the development of efficient NO₃⁻RR electrocatalysts, few has concerned about how to capture NH₃ from the electrolyte, despite that the production and capture of NH₃ are equally important to the practical application of NO₃⁻RR. Here, inspired by the fact that nearly all in situ generated NH₃ is gaseous at the electrode surface during the small‐current NO₃⁻RR, a “two‐in‐one” flow cell electrolyzer is smartly designed that integrates the chambers of NO₃⁻RR electrolysis and NH₃ capture through a commercial gas diffusion electrode, aiming at achieving the synchronization of NH₃ production and capture. Remarkably, this electrolyzer also enables rapid transport of NH₃ products away from the three‐phase reaction interfaces, thereby significantly promoting the conversion of NO₃⁻ to NH₃. By using robust electrocatalysts with the function like nanoreactors, the electrolyzer delivers a maximum ammonia Faradaic efficiency of 90.2%, along with a large current density (−528.0 mA cm⁻²) and NH₃ capture rate of 90.4%. Clearly, this work provides opportunities to concurrently produce and capture NH₃ and thus help the realization of nitrogen cycle.