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 NH3 synthesis. The difficulty of suppressing competing proton reduction, however, largely impedes its practical use. Herein, we design a hydrophobic octadecanethiol-modified Fe3P nanoarrays supported on carbon paper (C18@Fe3P/CP) to effectively repel water, concentrate N-2, and enhance N-2-to-NH3 conversion. Such catalyst achieves an NH3 yield of 1.80 x 10(-10) mol.s(-1).cm(-2) and a high Faradaic efficiency of 11.22% in 0.1 M Na2SO4, outperforming the non-modified Fe3P/CP (2.16 x 10(-11) mol.s(-1).cm(-2), 0.9%) counterpart. Significantly, C18@Fe3P/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 Fe3P can be well tuned by the thiol modification, which facilitates N-2 electroreduction activity and catalytic formation of NH3.

Automated summary

The study introduces a hydrophobic thiol-modified Fe3P nanoarray catalyst, which enhances the N-2 electroreduction activity and NH3 yield. The catalyst shows high efficiency and stability in 0.1 M Na2SO4.