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

Uranium-based catalysts have been regarded as promising candidates for N2 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 N2 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 NH3 and the NH3 yield rate of 18.7 μg h–1 mg–1 for N2 electroreduction. Operando XAS and isotope-labeling FTIR further unravel the preferred nitrogen adsorption reaction intermediate N–(2Oax-1 U-4Oeq) and confirm the key *N2Hy intermediate species derived from the fed N2 gas. Theoretical simulations demonstrate that the U–O atomic interface originated from U 5f-O 2p 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.