Enhanced nitrate reduction to ammonia using Cu-Ni catalyst: Synergistic mechanisms and reaction pathways

Area of Science:

• Materials Science
• Electrochemistry
• Environmental Science

Background:

• Nitrate pollution from industrialization and fertilizers disrupts the global nitrogen cycle.
• Electrochemical nitrate reduction (eNO3RR) offers a dual solution for nitrate removal and ammonia synthesis.
• Challenges include complex reaction pathways and slow kinetics in eNO3RR.

Purpose of the Study:

• To develop efficient carbon-coated Cu-Ni bimetallic catalysts for eNO3RR using MOF precursors.
• To elucidate the synergistic mechanisms between Cu and Ni in facilitating nitrate reduction.
• To improve the kinetics and performance of electrochemical nitrate-to-ammonia conversion.

Main Methods:

• Synthesis of carbon-coated Cu-Ni bimetallic catalysts from MOFs.
• Electrochemical characterization including rotating disk electrode (RDE) and electrochemical impedance spectroscopy (EIS).
• In-situ spectroscopy (FTIR, Raman) to analyze reaction intermediates and pathways.

Main Results:

• The Cu-Ni bimetallic catalyst demonstrated enhanced synergy, improving eNO3RR performance.
• Cu sites primarily facilitated nitrate-to-nitrite conversion, while Ni accelerated hydrogen generation and intermediate hydrogenation.
• Ni introduction enhanced nitrate adsorption and activation by shifting the catalyst's d-band center.

Conclusions:

• The developed MOF-derived Cu-Ni catalysts show significant promise for efficient eNO3RR.
• Understanding the synergistic effects is crucial for designing advanced electrocatalysts.
• This work provides a viable strategy for mitigating nitrate pollution and producing ammonia sustainably.