High spin polarized Fe2 cluster combined with vicinal nonmetallic sites for catalytic ammonia synthesis from a theoretical perspective. Issue 24 (10th November 2021)

• Record Type: Journal Article
• Authors: Zhu, Hongdan; Aarons, Jolyon; Peng, Qian
• Is Part Of: Inorganic chemistry frontiers. Volume 8:Issue 24(2021)
• Page Start: 5299
• Page End: 5311
• Publication Date: 2021-11-10
• Subjects: Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/d1qi01083b
• Languages: English
• ISSNs: 2052-1553

Abstract

Abstract : Compared to other Fe n ( n > 2) clusters, Fe2 cluster catalysts combined with vicinal nonmetallic sites are expected to be an ideal catalyst for ammonia synthesis with a lower N–H formation (0.47 eV) and N–N dissociation (0.50 eV) energy barrier at the same time. Abstract : An Fe2 catalyst combined with the vicinal nonmetallic sites may break the Brønsted–Evans–Polanyi limitation and lead to a more efficient ammonia synthesis than previously reported. Our theoretical calculations show that the Fe2 catalyst supported on graphitic carbon nitride (Fe2 /mpg-C3 N4 ) strongly favors hydrogenation of *N2 to form *NHNH2 species, which leads to low energy barriers for N–H formation (0.47 eV) and N–N dissociation (0.50 eV). In addition, B–N Lewis pairs constructed on the mpg-C3 N4 serve as nonmetallic sites that enable heterolysis of the H–H bond to overcome the relatively high energy barrier of hydrogen transfer. Through a comprehensive study of Fe n /mpg-C3 N4 ( n = 2, 3, 4) and Fe (211) catalysts, we conclude that synergistic Fe2 catalyst shows a significant advantage due to its high spin polarization and thus can avoid harsh reaction conditions for the thermal conversion of N2 to NH3 .