Sub-nm RuO Clusters on Pd Metallene for Synergistically Enhanced Nitrate Electroreduction to Ammonia

The electrochemical nitrate reduction to ammonia reaction (NO₃RR) has emerged as an appealing route for achieving both wastewater treatment and ammonia production. Herein, sub-nm RuO clusters anchored on a Pd metallene (RuO/Pd) are reported as a highly effective NO₃RR catalyst, delivering a maximum NH₃-Faradaic efficiency of 98.6% with a corresponding NH₃ yield rate of 23.5 mg h^-1 cm^-2 and partial a current density of 296.3 mA cm^-2 at -0.5 V vs RHE. Operando spectroscopic characterizations combined with theoretical computations unveil the synergy of RuO and Pd to enhance the NO₃RR energetics through a mechanism of hydrogen spillover and hydrogen-bond interactions. In detail, RuO activates NO₃^- to form intermediates, while Pd dissociates H₂O to generate *H, which spontaneously migrates to the RuO/Pd interface via a hydrogen spillover process. Further hydrogen-bond interactions between spillovered *H and intermediates makes spillovered *H desorb from the RuO/Pd interface and participate in the intermediate hydrogenation, contributing to the enhanced activity of RuO/Pd for NO₃^--to-NH₃ conversion.