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Enhanced N2 Affinity of 1T-MoS2 with a Unique Pseudo-six-membered Ring Consisting of N-Li-S-Mo-S-Mo for High Ambient Ammonia Electrosynthesis Performance
比哈伯法製氨更佳的電化學氮還原反應
S. B. Patil, H.-L. Chou, Y.-M. Chen, S.-H. Hsieh, C.-H. Chen, C.-C. Chang, S.-R. Li, Y.-C. Lee, Y.-S. Lin, H. Li, Y. J. Chang, Y.-H. Lai, and D.-Y. Wang*
2021/06/01
The Haber–Bosch process is widely used to convert atmospheric nitrogen (N2) into ammonia (NH3). However, the extreme reaction conditions and abundant carbon released by this process make it important to develop a greener NH3 production method. The electrochemical nitrogen reduction reaction (NRR) is an attractive alternative to the Haber–Bosch process. Herein, we demonstrated that molybdenum sulfide on nickel foil (1T-MoS2–Ni) with low crystallinity was an active NRR electrocatalyst. 1T-MoS2–Ni achieved a high faradaic efficiency of 27.66% for the NRR at −0.3 V (vs. RHE) in a LiClO4 electrolyte. In situ X-ray diffraction and ex situ X-ray photoemission analyses showed that lithium ions were intercalated into the 1T-MoS2 layers during the NRR. Moreover, theoretical calculations revealed the differences between six membered rings formed in the 1T-MoS2 and 2H-MoS2 systems with Li intercalation. The bond distances of d(Mo–N) and d(N–Li) of in Li–1T-MoS2 were found to be shorter than those in Li–2H-MoS2, resulting in a lower energy barrier of N2 fixation and higher NRR activity. Therefore, 1T-MoS2–Ni is promising as a scalable and low-cost NRR electrocatalyst with lower power consumption and carbon emission than the Haber–Bosch process.

自1950年以來，哈伯法製氨(Haber–Bosch)仍是目前植物所需氮肥的最主要來源，確保世界糧食無虞，哈伯也因此項發明獲得諾貝爾化學獎。此法是將大氣中的氮氣（N2）轉化為氨（NH3）。然而，需要極端的高溫高壓反應條件且釋放出的大量二氧化碳，使得開發更綠色的NH3生產方法變得急迫。電化學氮還原反應（NRR）就是最佳的替代方法。這裡，我們開發出一種塗佈在低結晶度的鎳箔（1T-MoS2-Ni）上的硫化鉬，可作為NRR電催化劑，NRR效率高達27.66％。本研究使用原位X光粉末繞射(XRD)和非原位X光發射光譜(XPS)分析，證實鋰離子在NRR反應期間插入1T-MoS2層。而且，理論計算也表明鋰在1T-MoS2和2H-MoS2系統中形成的六元環有所差異。尤其是Li-1T-MoS2與Li-2H-MoS2相比，其dMo–N和dN–Li的鍵長更短，可降低N2固定的能壘，促使NRR活性更高。因此，1T-MoS2-Ni有望成為具有較低轉換功率且低成本的NRR電催化劑，其所消耗的能源和低碳排放量都優於哈伯法。本研究使用TLS 09A, TLS 23A, TPS09A光束線。