Boosting electrochemical nitrite-ammonia conversion properties by a Cu foam@Cu₂O catalyst

Area of Science:

• Electrochemistry
• Materials Science
• Environmental Chemistry

Background:

• Electrocatalytic reduction of nitrite (NO₂^-) to ammonia (NH₃) offers a dual solution for wastewater treatment and sustainable ammonia production.
• Development of efficient and selective catalysts is crucial for optimizing this electrochemical process.

Purpose of the Study:

• To design and synthesize novel copper-based catalysts for the selective electroreduction of nitrite to ammonia.
• To investigate the role of oxygen vacancies in enhancing catalytic activity and selectivity.
• To elucidate the reaction mechanism and identify the rate-limiting step in the nitrite reduction process.

Main Methods:

• Synthesis of Cu₂O particles self-supported on Cu foam with engineered oxygen vacancies.
• Electrochemical characterization including cyclic voltammetry, linear sweep voltammetry, and chronoamperometry.
• Density functional theory (DFT) calculations to study reaction mechanisms and surface properties.

Main Results:

• The developed Cu₂O/Cu foam catalyst demonstrated a high NH₃ yield rate of 7510.73 μg h^-1 cm^-2.
• Achieved excellent Faradaic efficiency of 94.21% for NH₃ production at -0.6 V vs. RHE in 0.1 M PBS with 0.1 M NaNO₂.
• DFT calculations confirmed the critical role of oxygen vacancies in facilitating nitrite electroreduction and identified key reaction intermediates.

Conclusions:

• Cu₂O particles on Cu foam with oxygen vacancies are highly effective for selective nitrite electroreduction to ammonia.
• This study provides fundamental insights into the catalytic mechanism, paving the way for designing advanced Cu-based electrocatalysts.
• The developed catalyst system presents a promising approach for simultaneous wastewater remediation and ammonia electrosynthesis.