Pd-Doped Co₃ O₄ Nanoarray for Efficient Eight-Electron Nitrate Electrocatalytic Reduction to Ammonia Synthesis

Area of Science:

• Electrochemistry
• Materials Science
• Green Chemistry

Background:

• Ammonia (NH3) is crucial for fertilizer production and as a hydrogen-rich fuel.
• Electrochemical nitrate reduction reaction (NO3- RR) is a potential green route for NH3 synthesis.
• Current NO3- RR methods often involve complex multi-step reactions.

Purpose of the Study:

• To develop a highly efficient and selective electrocatalyst for NO3- RR to NH3.
• To investigate the performance of a palladium-doped cobalt oxide nanoarray electrode.
• To assess the catalyst's application in a zinc-nitrate battery system.

Main Methods:

• Fabrication of a palladium-doped cobalt oxide nanoarray on a titanium mesh (Pd-Co3O4/TM) electrode.
• Electrochemical characterization of the Pd-Co3O4/TM electrode for NO3- RR.
• Assembly of the catalyst into a zinc-nitrate battery for power generation and NH3 synthesis.

Main Results:

• The Pd-Co3O4/TM electrode achieved a high NH3 yield of 745.6 µmol h-1 cm-2.
• An exceptional Faradaic efficiency (FE) of 98.7% for NH3 was obtained at -0.3 V.
• The catalyst demonstrated strong stability and facilitated reaction kinetics through improved adsorption and optimized intermediate free energies.
• The Zn-NO3- battery system exhibited a power density of 3.9 mW cm-2 and an NH3 FE of 98.8%.

Conclusions:

• The Pd-Co3O4/TM electrode is a highly efficient and selective catalyst for electrochemical NH3 synthesis via NO3- RR.
• Palladium doping enhances the catalytic performance by optimizing adsorption and reaction pathways.
• The developed catalyst shows promise for integrated energy storage and green chemical production systems.