Modulating the Electrolyte Microenvironment in Electrical Double Layer for Boosting Electrocatalytic Nitrate...

Area of Science:

• Electrochemistry
• Materials Science
• Environmental Science

Background:

• Electrochemical nitrate reduction reaction (NO3RR) offers a sustainable route for ammonia production and wastewater treatment.
• Current NO3RR methods face challenges with low activity, selectivity, and Faraday efficiency.
• Optimizing the electrolyte microenvironment is crucial for improving NO3RR performance.

Purpose of the Study:

• To investigate the effect of alkali metal cations on the electrochemical nitrate reduction reaction (NO3RR).
• To enhance ammonia synthesis and nitrate remediation through electrolyte modulation.
• To understand the mechanism of cation influence on NO3RR.

Main Methods:

• Experimental electrochemical studies using bulk copper as a model catalyst.
• Theoretical calculations to analyze proton transport and reaction kinetics.
• Testing the cation effect on nanostructured copper/cuprous oxide and nickel phosphide catalysts.

Main Results:

• Ammonia synthesis performance followed the trend Li+
• Theoretical studies confirmed increased proton transport and reaction rates with K+.
• Nanostructured catalysts achieved near-100% Faraday efficiency and >99% nitrate conversion.
• High-purity ammonium chloride (NH4Cl) production demonstrated with Cu/Cu2O in K+-containing electrolytes.

Conclusions:

• Alkali metal cations, particularly K+, significantly enhance NO3RR performance by modulating the electrical double layer (EDL) microenvironment.
• The cation-mediated strategy is general and effective for various catalysts.
• This approach provides a pathway for efficient ammonia synthesis and nitrate remediation.