Enhancing electrocatalytic N2-to-NH3 fixation by suppressing hydrogen evolution with alkylthiols modified Fe3P nanoarrays

Electrocatalytic N 2 reduction provides an attractive alternative to Haber-Bosch process for artificial NH 3 synthesis. The difficulty of suppressing competing proton reduction, however, largely impedes its practical use. Herein, we design a hydrophobic octadecanethiol-modified Fe 3 P nanoarrays supported on carbon paper (C18@Fe 3 P/CP) to effectively repel water, concentrate N 2 , and enhance N 2 -to-NH 3 conversion. Such catalyst achieves an NH 3 yield of 1.80 × 10 −10 mol·s −1 ·cm −2 and a high Faradaic efficiency of 11.22% in 0.1 M Na 2 SO 4 , outperforming the non-modified Fe 3 P/CP (2.16 × 10 −11 mol·s −1 ·cm −2 , 0.9%) counterpart. Significantly, C18@Fe 3 P/CP renders steady N 2 -fixing activity/selectivity in cycling test and exhibits durability for at least 25 h. First-principles calculations suggest that the surface electronic structure and chemical activity of Fe 3 P can be well tuned by the thiol modification, which facilitates N 2 electroreduction activity and catalytic formation of NH 3 .