The electrochemical reduction of nitrate ions to valuable ammonia enables the recovery of nitrate pollutants from industrial wastewater, thereby synchronously balancing the nitrogen cycle and achieving NH₃ production. However, the currently reported electrocatalysts still suffer from the low NH₃ yield rate, NH₃ Faradaic inefficiency, and NH₃ partial current density. Herein, a strategy based on the regulation of the d-band center by Ru doping is presented to boost ammonia production. Theoretical calculations unravel that the Ru dopant in Ni metal–organic framework shifts the d-band center of the neighboring Ni sites upward, optimizing the adsorption strength of the N-intermediates, resulting in greatly enhanced nitrate reduction reaction performance. The synthesized Ru-doped Ni metal–organic framework rod array electrode delivers a NH₃ yield rate of 1.31 mmol h^–1 cm^–2 and NH₃ Faradaic efficiency of 91.5% at −0.6 V versus reversible hydrogen electrode, as well as good cycling stability. In view of the multielectron transfer in nitrate reduction and electrocatalytic activity, the Zn-NO₃^– battery is assembled by this electrode and Zn anode, which delivers a high open-circuit voltage of 1.421 V and the maximum output power density of 4.99 mW cm^–2, demonstrating potential application value.

中文翻译：

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调节金属-有机框架的 d 波段中心以实现高效的硝酸盐还原反应和硝酸锌电池


硝酸根离子的电化学还原为有价值的氨，能够从工业废水中回收硝酸盐污染物，从而同步平衡氮循环并实现 NH₃ 生产。然而，目前报道的电催化剂仍然存在 NH₃ 良率低、NH₃ 法拉第效率低和 NH₃ 部分电流密度的问题。在此，提出了一种基于 Ru 掺杂调节 d 波段中心的策略，以促进氨的产生。理论计算表明，Ni 金属-有机框架中的 Ru 掺杂剂使相邻 Ni 位点的 d 波段中心向上移动，优化了 N 中间体的吸附强度，从而大大提高了硝酸盐还原反应性能。与可逆氢电极相比，合成的 Ru 掺杂 Ni 金属有机框架棒阵列电极在 -0.6 V 下的 NH₃ 产率为 1.31 mmol h^–1 cm^–2，NH ₃ 法拉第效率为 91.5%，以及良好的循环稳定性。鉴于硝酸盐还原和电催化活性中的多电子转移，Zn-NO₃^– 电池由该电极和 Zn 阳极组装而成，可提供 1.421 V 的高开路电压和 4.99 mW cm^–2 的最大输出功率密度，显示出潜在的应用价值。