Ru Single Atoms Anchored in Metal Borides Enable Hydrogen Spillover for Superior Electrochemical Ammonia Production

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.