Hydrophobicity Tailoring of Ferric Covalent Organic Framework/MXene Nanosheets for High-Efficiency Nitrogen...

Electrocatalytic nitrogen reduction reaction (NRR) represents a promising sustainable approach for NH₃ synthesis. However, the poor NRR performance of electrocatalysts is a great challenge at this stage, mainly owing to their low activity and the competitive hydrogen evolution reaction (HER). Herein, 2D ferric covalent organic framework/MXene (COF-Fe/MXene) nanosheets with controllable hydrophobic behaviors are successfully prepared via a multiple-in-one synthetic strategy. The boosting hydrophobicity of COF-Fe/MXene can effectively repel water molecules to inhibit the HER for enhanced NRR performances. By virtue of the ultrathin nanostructure, well-defined single Fe sites, nitrogen enrichment effect, and high hydrophobicity, the 1H,1H,2H,2H-perfluorodecanethiol modified COF-Fe/MXene hybrid shows a NH₃ yield of 41.8 µg h^-1 mg_cat. ^-1 and a Faradaic efficiency of 43.1% at -0.5 V versus RHE in a 0.1 m Na₂ SO₄ water solution, which are vastly superior to the known Fe-based catalysts and even to the noble metal catalysts. This work provides a universal strategy to design and synthesis of non-precious metal electrocatalysts for high-efficiency N₂ reduction to NH₃ .