A Symmetric Cogeneration Fuel Cell for Coupled Production of Hydrogen, Ammonia and Formate

ABSTRACT Electrochemical synthesis offers a sustainable route to convert abundant feedstocks into value‐added chemicals under mild conditions and couple chemical manufacturing with renewable electricity. However, its practical impact is often limited by system‐level energy inefficiency, motivating rational reaction pairing to reduce energy input while upgrading product value. Here, we develop a symmetric cogeneration fuel cell that couples one‐electron formaldehyde oxidation reaction with nitrate reduction to co‐produce hydrogen, ammonia and formate while generating electricity. This symmetric cell was enabled by a FOR and NO ₃ RR bifunctional Cu nano leaves coated with Co(OH) ₂ catalyst, which constructs an interfacial hydrogen network capable of synchronizing NO ₃ ^– reduction with active hydrogen delivery. As a result, the catalyst achieves an industrial current density of 2.35 A cm ⁻² at −1 V vs RHE with a high Faradaic efficiency of 96.38%. Operating at 35°C, the symmetric cell delivers a peak power density of 13.24 mW cm ⁻² , representing the highest value reported to date for unassisted ammonia synthesis systems. This work establishes a simple yet versatile strategy for integrating value‐added chemical synthesis with electricity generation and offers a generalizable framework for other paired electrosynthesis processes.