Sub-nm RuO_<i>x</i> Clusters on Pd Metallene for Synergistically Enhanced Nitrate Electroreduction to Ammonia.

Abstract

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_<i>x</i> clusters anchored on a Pd metallene (RuO_<i>x</i>/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. <i>Operando</i> spectroscopic characterizations combined with theoretical computations unveil the synergy of RuO_<i>x</i> and Pd to enhance the NO₃RR energetics through a mechanism of hydrogen spillover and hydrogen-bond interactions. In detail, RuO_<i>x</i> activates NO₃^- to form intermediates, while Pd dissociates H₂O to generate *H, which spontaneously migrates to the RuO_<i>x</i>/Pd interface via a hydrogen spillover process. Further hydrogen-bond interactions between spillovered *H and intermediates makes spillovered *H desorb from the RuO_<i>x</i>/Pd interface and participate in the intermediate hydrogenation, contributing to the enhanced activity of RuO_<i>x</i>/Pd for NO₃^--to-NH₃ conversion.