Enhancing electrocatalytic N2-to-NH3 fixation by suppressing hydrogen evolution with alkylthiols modified Fe3P nanoarrays
Tong Xu, Jie Liang, Yuanyuan Wang, Shaoxiong Li, Zhaobai Du, Tingshuai Li, Qian Liu, Yonglan Luo, Fang Zhang, Xifeng Shi, Bo Tang, Qingquan Kong, Abdullah M. Asiri, Chun Yang, Dongwei Ma, Xuping Sun
Abstract
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 .