The electrochemical reduction of nitrates (NO₃⁻) enables a pathway for the carbon neutral synthesis of ammonia (NH₃), via the nitrate reduction reaction (NO₃RR), which has been demonstrated at high selectivity. However, to make NH₃ synthesis cost-competitive with current technologies, high NH₃ partial current densities (j_NH3) must be achieved to reduce the levelized cost of NH₃. Here, the high NO₃RR activity of Fe-based materials is leveraged to synthesize a novel active particle-active support system with Fe₂O₃ nanoparticles supported on atomically dispersed Fe–N–C. The optimized 3×Fe₂O₃/Fe–N–C catalyst demonstrates an ultrahigh NO₃RR activity, reaching a maximum j_NH3 of 1.95 A cm⁻² at a Faradaic efficiency (FE) for NH₃ of 100% and an NH₃ yield rate over 9 mmol hr⁻¹ cm⁻². Operando XANES and post-mortem XPS reveal the importance of a pre-reduction activation step, reducing the surface Fe₂O₃ (Fe³⁺) to highly active Fe⁰ sites, which are maintained during electrolysis. Durability studies demonstrate the robustness of both the Fe₂O₃ particles and Fe–N_x sites at highly cathodic potentials, maintaining a current of −1.3 A cm⁻² over 24 hours. This work exhibits an effective and durable active particle-active support system enhancing the performance of the NO₃RR, enabling industrially relevant current densities and near 100% selectivity.

中文翻译：

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在单原子 Fe-N-C 上协同 Fe2O3 纳米粒子，在工业电流密度下将硝酸盐还原为氨

氧化氮物种的电化学还原为碳中性合成氨（NH3）。氮的氧化程度最高的形式是硝酸盐 (NO3-) 可以还原为 NH3通过电催化硝酸盐还原反应（NO3RR），已被证明具有高选择性。然而，为了使NH3与现有技术相比，合成成本具有竞争力，高 NH3部分电流密度（j氨）必须实现以降低NH的平准化成本3。在这里，我们利用高NO3铁基材料的 RR 活性合成新型活性颗粒活性载体系统2氧3纳米颗粒负载在原子分散的 Fe-N-C 上。通过协同纳米颗粒和单原子位点的活性，优化的 3xFe2氧3/Fe-N-C 催化剂表现出超高的 NO3RR活动，达到最大j氨1.95安厘米−2NH 的法拉第效率 (FE)3100% 和 NH3产率超过 9 mmol hr−1厘米−2（相对于 RHE 为 ‐1.2 V）。原位 XANES 和死后 XPS 揭示了预还原活化步骤的重要性，减少了表面 Fe2氧3(铁3+) 到高活性 Fe0电解过程中保留的位点，以实现超高NO3RR 活动。耐久性研究证明了 Fe 的稳健性2氧3颗粒和Fe-NX处于高阴极电位的位点，维持 ‐1.3 A cm 的电流−2超过 24 小时，接近统一的 FE氨（相对于 RHE 为 ‐1.0 V）。这项工作展示了一种有效且持久的活性颗粒活性支持系统，可增强 NO 的性能3RR，实现工业相关的电流密度和接近 100% 的选择性。本文受版权保护。版权所有