Atomically Dispersed W1–O3 Bonded on Pd Metallene for Cascade NO Electroreduction to NH3

Electrocatalytic NO reduction to NH₃ (NORR) offers a prospective method for removing hazardous NO and producing valuable NH₃ simultaneously. Herein, we demonstrate that atomically dispersed W on Pd metallene (W₁Pd) can be an efficient and robust NORR catalyst. Atomic coordination characterizations unravel that W single atoms exist as W₁–O₃ moieties bonded on Pd metallene. In situ spectroscopic measurements and theoretical calculations reveal the synergistic cascade effect of W₁–O₃ and Pd metallene to promote the NORR energetics of W₁Pd, in which the activation and hydrogenation of NO occur on W₁–O₃, while Pd metallene dissociates H₂O and donates protons required for hydrogenation of NO to NH₃. Consequently, W₁Pd exhibits an NH₃ yield rate of 758.5 μmol h^–1 cm^–2 with an NH₃-Faradaic efficiency of 91.3% in a flow cell (272.1 μmol h^–1 cm^–2 and 93.7% in H-type cells), ranking almost the highest performance among all reported NORR catalysts.