The electrochemical reduction of nitrate to ammonia (NRA) in neutral media offers a viable route toward sustainable nitrogen recycling and environmental purification. However, the development of efficient catalysts that simultaneously achieve high current density, Faradaic efficiency, and selectivity remains elusive. In this study, we present a rationally designed metasequoia-like iron-doped copper (CuFe) nanocrystal catalyst that overcomes these challenges through synergistic structural and electronic engineering. The optimized Cu₄₉Fe₁ sample delivers a remarkable current density of 55.6 mA cm⁻² at −0.7 V vs. RHE—2.1 times higher than pure Cu—and achieves a Faradaic efficiency of up to 94.5% with 86.8% ammonia selectivity under neutral conditions.
The catalyst was fabricated via electrodeposition in an electrolyte containing controlled Fe concentrations, resulting in a unique hierarchical nanostructure resembling a sequoia tree. SEM and TEM imaging confirm the preservation of this morphology across various doping levels (1–5 at.%), with no evidence of phase segregation. HRTEM analysis reveals lattice spacing of 0.210 nm corresponding to Cu(111) planes, indicating high crystallinity. Elemental mapping demonstrates uniform distribution of both Cu and Fe throughout the structure, confirming atomic-level incorporation rather than surface enrichment or clustering.
XRD patterns show identical diffraction peaks for CuFe and pure Cu, confirming retention of the face-centered cubic structure without secondary phases. BET analysis indicates comparable surface areas (~5.9 m² g⁻¹) among all samples, suggesting that the catalytic performance differences are not due to surface area variation. XPS measurements reveal a negative shift in Cu 2p binding energies in CuFe compared to pure Cu, indicating electron donation from Fe to Cu.PSMG2 Antibody Autophagy This charge transfer is further supported by the presence of Fe²⁺/Fe³⁺ species in the Fe 2p spectrum, which may contribute to enhanced surface reactivity.
Electrochemical tests in neutral 0.1 M K₂SO₄ with 2 mM KNO₃ demonstrate that Fe doping significantly improves nitrate reduction kinetics. LSV curves show that Cu₄₉Fe₁ exhibits the most favorable half-wave potential (−0.36 V vs. RHE). Koutecký–Levich analysis confirms an eight-electron transfer process, consistent with complete conversion of NO₃⁻ to NH₃. The kinetic current density of Cu₄₉Fe₁ reaches 55.6 mA cm⁻² at −0.7 V vs. RHE, far exceeding that of pure Cu (26.3 mA cm⁻²).
A H-type cell with Nafion membrane was used to evaluate ammonia selectivity and yield. At −0.74 V vs. RHE, Cu₄₉Fe₁ achieved a nitrate conversion rate of 96.9%, ammonia yield of 0.23 mmol h⁻¹ cm⁻², and selectivity of 86.8%. These values surpass those of control samples: plain Cu (40.FTO Antibody Biological Activity 9% FE, 0.PMID:34332925 1 mmol h⁻¹ cm⁻²), Cu₉₉Fe₁ (65.8% FE, 0.128 mmol h⁻¹ cm⁻²), and Cu₁₉Fe₁ (82.7% FE, 0.213 mmol h⁻¹ cm⁻²). The Cu foam substrate alone showed negligible activity (3.5% selectivity, 0.004 mmol h⁻¹ cm⁻²), underscoring the necessity of the engineered nanostructure and composition.
Stability testing revealed no significant degradation after four consecutive cycles, with maintained Faradaic efficiency and ammonia yield. Post-test SEM and XRD analyses confirmed structural and morphological stability, indicating robustness under operational conditions. DFT calculations show that Fe doping shifts the Cu d-band center to a deeper energy level (−2.47 eV vs. −2.41 eV for pure Cu), leading to optimal adsorption energies for reaction intermediates (*NO₃⁻, *NO₂, *NO, *N, *NHₓ), thereby promoting selective ammonia formation while suppressing hydrogen evolution and partial reduction pathways.
This work establishes a new benchmark for electrocatalytic NRA in neutral media. The integration of metasequoia-like architecture, atomic-scale Fe doping, and rational electronic tuning enables exceptional performance in terms of activity, selectivity, and stability. The findings provide critical insights into the design principles for advanced catalysts targeting environmental remediation and green chemical synthesis.MedChemExpress (MCE) offers a wide range of high-quality research chemicals and biochemicals (novel life-science reagents, reference compounds and natural compounds) for scientific use. We have professionally experienced and friendly staff to meet your needs. We are a competent and trustworthy partner for your research and scientific projects.Related websites: https://www.medchemexpress.com