Engineering vacancy and hydrophobicity of two-dimensional TaTe₂ for efficient and stable electrocatalytic N₂...

Demand for ammonia continues to increase to sustain the growing global population. The direct electrochemical N₂ reduction reaction (NRR) powered by renewable electricity offers a promising carbon-neutral and sustainable strategy for manufacturing NH₃, yet achieving this remains a grand challenge. Here, we report a synergistic strategy to promote ambient NRR for ammonia production by tuning the Te vacancies (V_Te) and surface hydrophobicity of two-dimensional TaTe₂ nanosheets. Remarkable NH₃ faradic efficiency of up to 32.2% is attained at a mild overpotential, which is largely maintained even after 100 h of consecutive electrolysis. Isotopic labeling validates that the N atoms of formed NH₄ ⁺ originate from N₂. In situ X-ray diffraction indicates preservation of the crystalline structure of TaTe₂ during NRR. Further density functional theory calculations reveal that the potential-determining step (PDS) is ∗NH₂ + (H⁺ + e^-) → NH₃ on V_Te-TaTe₂ compared with that of ∗ + N₂ + (H⁺ + e^-) → ∗N-NH on TaTe₂. We identify that the edge plane of TaTe₂ and V_Te serve as the main active sites for NRR. The free energy change at PDS on V_Te-TaTe₂ is comparable with the values at the top of the NRR volcano plots on various transition metal surfaces.