Efficient electrochemical nitrate reduction with CoFe@Cu foam electrode: experimental study and high N2 selectivity

Abstract

Creating effective electrocatalysts has been seen as a potential solution for wastewater contaminated with nitrate. In this research, we employed copper foam (Cu foam) as a substrate to successfully fabricate a novel non-precious three-dimensional CoFe@Cu foam electrode, exhibiting outstanding catalytic activity and stability. The study found that this material shows significant potential as a cathode for the electrochemical reduction of nitrates. Notably, under a current density of 30 mA/cm², the CoFe@Cu foam cathode demonstrates excellent performance in removing nitrate from simulated wastewater, achieving an efficiency of up to 96.3% within 60 min. This result is significantly higher than the 20.3% removal efficiency observed with the copper foam electrode under the same conditions, highlighting the clear advantage of the CoFe@Cu foam cathode in the electrochemical reduction of nitrates and its superior capability for effective nitrate removal. The enhanced functionality can be attributed to the increased quantity of active sites and the synergistic relationship between iron (Fe) and cobalt (Co). Additionally, the impact of chloride ions (Cl⁻) on the reduction of ammonium nitrogen (NH₄⁺-N) formation and the enhancement of total nitrogen (TN) removal was evaluated. The results showed that the addition of 1.0 g/L Cl⁻ significantly reduced NH₄⁺-N formation and achieved a 100% TN removal rate after 90 min of treatment. Based on an analysis of the experimental results, a possible pathway for nitrate electroreduction was proposed.