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

Abstract

Abstract The electrochemical nitrate‐to‐ammonia reduction reaction (NO 3 RR) 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 NO 3 RR via an unconventional [6 + 2] electron‐transfer tandem pathway. Unlike the traditional [2 + 6] tandem pathway, the Fe sites predominantly reduce NO 3− to *NH 2 OH intermediate, which subsequently spills over onto the Co sites for further protonation. This unconventional tandem pathway effectively avoids the release of NO 2− and guarantees selective NH 3 production. The CoFe‐cMOFs achieve 94.3% NH 3 ‐producing Faradaic efficiency with a yield rate of 14.1 mg h −1 cm −2 in neutral electrolyte. The Zn‐NO 3 − battery prototype incorporating CoFe‐cMOFs exhibits 3.6 mW cm −2 peak power density with stable NH 3 production. This work proposes a mechanistic breakthrough in tandem pathway regulation for selective electrochemical ammonia synthesis.