Cooperating oxidative half-reaction deactivate electrocatalyst for nitrate reduction in real wastewater

Area of Science:

• Environmental Science
• Electrochemistry
• Materials Science

Background:

• Electrocatalytic nitrate reduction to ammonia (eNO3RA) offers a dual solution for wastewater nitrate mitigation and ammonia recovery.
• The complex matrix of real wastewater poses significant challenges to catalyst stability, impacting process efficiency.

Purpose of the Study:

• To comprehensively investigate the stability of copper oxide (CuxO) nanowires for eNO3RA in real wastewater conditions.
• To identify the mechanisms of catalyst deactivation and the factors influencing performance.

Main Methods:

• Preparation of CuxO nanowire catalysts.
• Electrocatalytic testing of CuxO nanowires in simulated and real wastewater.
• Analysis of catalyst deactivation mechanisms using electrochemical and material characterization techniques.

Main Results:

• CuxO nanowires exhibited irreversible deactivation in short-term eNO3RA tests in real wastewater, with ammonia selectivity dropping significantly.
• Long-term performance in confined electrolytes showed recovery after oven drying, suggesting reversible aspects.
• Catalyst deactivation was attributed to nanowire aggregation and Cu+ oxidation to Cu2+, with chloride ions identified as a key contributor.

Conclusions:

• The stability of CuxO nanowires is compromised in real wastewater due to aggregation and oxidation, particularly influenced by chloride ions.
• Understanding these deactivation pathways is crucial for designing robust electrochemical systems for wastewater treatment.
• Further research is needed to develop more stable electrocatalysts for effective eNO3RA in complex matrices.