Engineered Fe-Cu Synergy for Selective Nitrate Electroreduction to Ammonia at High Current Density

The electrochemical reduction of nitrate (eNO3RR) for ammonia (NH3) synthesis effectively reduces nitrate (NO3–) pollution in water bodies while offering a potential application for NH3 production under ambient conditions. However, this process is limited by the generation of byproducts from multiple competitive side reactions and the high activation energy barrier for NO3– conversion to NH3. This study reports a series of efficient Fe-Cu2O catalysts, featuring dilute Fe doped into the Cu2O lattice, generating lattice-incorporated Fe-Cu synergistic motifs that electronically modulate the surrounding Cu–O framework, which achieve great current density up to 500 mA cm–2 in an H-cell, a high NH3 yield rate up to 4.99 ± 0.12 mmol h–1 mgcat–1, and an excellent Faraday efficiency of 94.11 ± 2.2%. Electrochemical performance tests demonstrate that Fe doping significantly improves both catalytic activity and reaction selectivity. Various characterization techniques reveal interactions between Fe and Cu sites, altering the efficient electron density, which optimizes electron transfer and NO3– reduction efficiency. Theoretical calculations indicate that the synergistic coordination between Fe and Cu reduces the overall reaction energy barrier and enhanced selectivity. This study extends traditional catalyst material designs to new application scenarios, providing new insights and methodologies for NO3– treatment and electrochemical NH3 synthesis, thereby broadening the application scope of eNO3RR-related technologies.