Pd‐Doped Co3O4 Nanoarray for Efficient Eight‐Electron Nitrate Electrocatalytic Reduction to Ammonia Synthesis

Ammonia (NH3) is an indispensable feedstock for fertilizer production and one of the most ideal green hydrogen rich fuel. Electrochemical nitrate (NO3−) reduction reaction (NO3−RR) is being explored as a promising strategy for green to synthesize industrial‐scale NH3, which has nonetheless involved complex multi‐reaction process. This work presents a Pd‐doped Co3O4 nanoarray on titanium mesh (Pd‐Co3O4/TM) electrode for highly efficient and selective electrocatalytic NO3−RR to NH3 at low onset potential. The well‐designed Pd‐Co3O4/TM delivers a large NH3 yield of 745.6 µmol h−1 cm−2 and an extremely high Faradaic efficiency (FE) of 98.7% at −0.3 V with strong stability. These calculations further indicate that the doping Co3O4 with Pd improves the adsorption characteristic of Pd‐Co3O4 and optimizes the free energies for intermediates, thereby facilitating the kinetics of the reaction. Furthermore, assembling this catalyst in a Zn‐NO3− battery realizes a power density of 3.9 mW cm−2 and an excellent FE of 98.8% for NH3.