Regulating the\nd‑Band Center of Metal–Organic\nFrameworks for Efficient Nitrate Reduction Reaction and Zinc-Nitrate\nBattery

The electrochemical reduction of nitrate ions to valuable\nammonia\nenables the recovery of nitrate pollutants from industrial wastewater,\nthereby synchronously balancing the nitrogen cycle and achieving NH<sub>3</sub> production. However, the currently reported electrocatalysts\nstill suffer from the low NH<sub>3</sub> yield rate, NH<sub>3</sub> Faradaic inefficiency, and NH<sub>3</sub> partial current density.\nHerein, a strategy based on the regulation of the d-band center by\nRu doping is presented to boost ammonia production. Theoretical calculations\nunravel that the Ru dopant in Ni metal–organic framework shifts\nthe d-band center of the neighboring Ni sites upward, optimizing the\nadsorption strength of the N-intermediates, resulting in greatly enhanced\nnitrate reduction reaction performance. The synthesized Ru-doped Ni\nmetal–organic framework rod array electrode delivers a NH<sub>3</sub> yield rate of 1.31 mmol h<sup>–1</sup> cm<sup>–2</sup> and NH<sub>3</sub> Faradaic efficiency of 91.5% at −0.6 V\nversus reversible hydrogen electrode, as well as good cycling stability.\nIn view of the multielectron transfer in nitrate reduction and electrocatalytic\nactivity, the Zn-NO<sub>3</sub><sup>–</sup> battery is assembled\nby this electrode and Zn anode, which delivers a high open-circuit\nvoltage of 1.421 V and the maximum output power density of 4.99 mW\ncm<sup>–2</sup>, demonstrating potential application value.