Neighboring effect in PtCuSnCo alloy catalysts for precisely regulating nitrate adsorption and deoxidation to achieve 100% faradaic efficiency in ammonia synthesis

The electrochemical reduction of nitrate (NO 3 − ) to ammonia (NH 3 ) (NO 3 RR) represents an environmentally sustainable strategy for NH 3 production while concurrently addressing water pollution challenges. Nevertheless, the intrinsic complexity of this multi-step reaction severely constrains both the selectivity and efficiency of NO 3 RR. Copper-based electrocatalysts have been extensively investigated for NO 3 RR but often suffer from nitrite (NO 2 − ) accumulation, which stems from insufficient NO 3 − adsorption strength. This limitation often leads to rapid catalyst deactivation, hindered hydrogenation pathways, and reduced overall efficiency. Herein, we report a one-step green chemical reduction method to synthesize PtCuSnCo quarternary alloy nanoparticles with homogeneously distributed elements. Under practical NO 3 − concentrations, the optimized catalyst exhibited an impressive Faradaic efficiency approaching 100% and an outstanding selectivity of 95.6 ± 2.9%. Mechanistic insights uncovered that SnCo sites robustly facilitated NO 3 − adsorption, complemented by the proficiency of PtCu sites in NO 3 − reduction. The synergistic spatial neighborhood effect between SnCo and PtCu sites efficiently stabilizes NO 3 − deoxygenation and suppresses NO 2 − accumulation. This tandem architecture achieves a finely tuned balance between adsorption strength and deoxygenation kinetics, enabling highly selective and efficient NO 3 RR. Our findings emphasize the indispensable role of engineered multi-metallic catalysts in overcoming persistent challenges of NO 3 RR, paving the way for advanced NH 3 synthesis and environmental remediation. The synergistic spatial neighborhood effect between SnCo and PtCu sites efficiently stabilizes NO 3 − deoxygenation and suppresses NO 2 − accumulation, thereby optimizing the overall electrochemical conversion pathway and markedly enhancing NH 3 production efficiency.