fig5

Figure 5. Practical applicability, durability evaluation, and cost analysis of HS-LFP for nitrate-to-ammonia electrosynthesis. (A) Schematic illustration of the flow-cell configuration for continuous electrocatalytic nitrate reduction, where HS-LFP serves as the cathodic catalyst for NO₃^-RR and IrO₂@Ti is used as the anodic OER electrode; (B) Cycling stability of HS-LFP over 30 consecutive runs in simulated wastewater containing 1 M KOH, 0.1 M KNO₃, 0.1 M KCl, and 0.1 M K₂SO₄ at -0.4 V vs. RHE, showing the NH₃ Faradaic efficiency and NH₃ yield rate; (C) Long-term NH₃ Faradaic efficiency of HS-LFP during continuous operation in the flow-cell system; (D) Simplified cost comparison under different accounting scopes, including HS-LFP (direct preparation cost only) and representative literature values for Fe-N-C/MOF and Fe-N-C/SAC catalysts. CEM: Cation exchange membrane; HS-LFP: the S-LFP-derived slag; OER: oxygen evolution reaction; NO₃^-RR: nitrate reduction reaction; FE: Faradaic Efficiency; SAC: single-atom catalyst; MOF: metal-organic framework; RHE: reversible hydrogen electrode.