Realizing Unconventional Tandem Nitrate Reduction for Efficient Ammonia Electrosynthesis Enabled by Co,Fe Dual‐Site Conjugated Metal Organic Frameworks

Abstract

The electrochemical nitrate‐to‐ammonia reduction reaction (NO3RR) offers a sustainable route for carbon‐neutral chemical synthesis, while the intricate multi‐electron/proton transfer processes and unstable intermediates pose significant challenges in attaining high selectivity and efficiency. This study demonstrates a Co,Fe bimetallic conjugated metal organic frameworks (CoFe‐cMOFs) that enable efficient NO3RR via an unconventional [6+2] electron‐transfer tandem pathway. Unlike the traditional [2+6] tandem pathway, the Fe sites predominantly reduce NO3− to *NH2OH intermediate, which subsequently spills over onto the Co sites for further protonation. This unconventional tandem pathway effectively avoids the release of NO2− and guarantees selective NH3 production. The CoFe‐cMOFs achieve 94.3% NH3‐producing Faradaic efficiency with a yield rate of 14.1 mg h−1 cm−2 in neutral electrolyte. The Zn‐NO3− battery prototype incorporating CoFe‐cMOFs exhibits 3.6 mW cm−2 peak power density with stable NH3 production. This work proposes a mechanistic breakthrough in tandem pathway regulation for selective electrochemical ammonia synthesis.