The electrochemical reduction of nitrate represents a promising and sustainable route for valuable ammonia generation. However, a vital challenge in the nitrate reduction reaction is an insufficient supply of active hydrogen (*H) and slow kinetics at a low working potential, which results in low production efficiency and high energy consumption. Here, we report the single-atom Ru decorated nanoporous metal borides as a high-performance electrochemical nitrate reduction electrocatalyst utilizing an atomic-scale hydrogen spillover effect. Notably, the RuSA/np-Ni3B exhibits a high NH3 Faradaic efficiency of 96.2%, a NH3 yield of 30.4 mg h-1 mg-1, and an energy efficiency of 39.1% at -0.1 V vs. RHE. In situ electrochemical characterizations and theoretical calculations reveal that single-atom Ru anchored in nanoporous Ni3B not only can efficiently dissociate water into *H and simultaneously promote the *H spillover for increasing *H coverage on the surface, but also can optimize surface states of Ni3B active centers, which synergistically reduces the hydrogenation energy barrier for converting nitrate into valuable ammonia products. A two-electrode electrolyzer integrating nitrate reduction reaction with furfuryl alcohol oxidation reaction achieves current density of 1 A cm-2 at -1.72 V with 100 h stability, improving the energy efficiency and economy of the system.
Keywords: electrochemical nitrate reduction reaction * metal borides * hydrogen spillover * nanoporous structure.
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