Regulating the d-Band Center of Metal–Organic Frameworks for Efficient Nitrate Reduction Reaction and Zinc-Nitrate Battery
Yuanhui Yao, Xiaofei Wei, Haiqiao Zhou, Kai Wei, Bin Kui, Fangfang Wu, Liang Chen, Wei Wang, Fangna Dai, Peng Gao, Nana Wang, Wei Ye
Abstract
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 NH 3 production. However, the currently reported electrocatalysts still suffer from the low NH 3 yield rate, NH 3 Faradaic inefficiency, and NH 3 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 NH 3 yield rate of 1.31 mmol h –1 cm –2 and NH 3 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-NO 3 – 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.