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

Abstract

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 Co₃ O₄ nanoarray on titanium mesh (Pd-Co₃ O₄ /TM) electrode for highly efficient and selective electrocatalytic NO₃ ^- RR to NH₃ at low onset potential. The well-designed Pd-Co₃ O₄ /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 Co₃ O₄ with Pd improves the adsorption characteristic of Pd-Co₃ O₄ 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 .