Amplified Single-Atom U-O Interfacial Effect Originated from U 5 f -O 2 p Hybridization over UO x /GO for Enhanced Nitrogen Reduction Reaction.

Uranium-based catalysts have been regarded as promising candidates for N fixation owing to the low-valent uranium metal active sites possessing the ability to enhance the electron back-donating to the π* antibonding orbitals of N for N≡N dissociation. Herein, we report a directional half-wave rectified alternating current electrochemical method to confine oxygen-rich uranium precursors over ultrathin 2D GO nanosheets. The as-prepared uranium catalysts exhibit a considerable Faradaic efficiency of 12.7% for NH and the NH yield rate of 18.7 μg h mg for N electroreduction. Operando XAS and isotope-labeling FTIR further unravel the preferred nitrogen adsorption reaction intermediate N-(2O-1 U-4O) and confirm the key *NH intermediate species derived from the fed N gas. Theoretical simulations demonstrate that the U-O atomic interface originated from U 5-O 2 orbital hybridization can accumulate partial charge from GO, which can facilitate the N≡N dissociation and lower the thermodynamic energy barrier of the first hydrogenation step.