Synergism of Hydrogen-Induced Interstitial Effect and Gold-Induced Alloying Effect in PdAuH Metallene for Urea Electrosynthesis from Nitrate and Carbon Dioxide

Urea is a common agricultural fertilizer and industrial raw material, but at present, the traditional industrial production of urea is energy-and pollution-intensive. Electrocatalytic coupling of CO₂ and ubiquitous nitrogen sources to synthesize urea is considered as a promising alternative method but requiring high-performance catalysts to boost the C–N coupling electrocatalysis process. Herein, hydrogen-intercalated Pd–Au bimetallene (PdAuHene) was prepared by a three-step method and used for electrosynthesis of urea from NO₃^– and CO₂, deriving an optimum urea Faradaic efficiency of 33.88% and yield rate of 6.68 mmol g^–1 h^–1 at an applied potential of −0.6 V vs RHE. Detailed material characterizations and electrochemical studies reveal that the metallene structure with ultrathin thickness could improve atomic utilization of precious metal atoms, and the introduction of Au and H atoms could adjust the electronic structure of Pd atoms, regulate the evolution pathway of key N-/C-intermediates, and promote the C–N coupling to form urea.