Molecular and Electronic Structures of Transition-Metal Macrocyclic Complexes as Related to Catalyzing Oxygen Reduction Reactions: A Density Functional Theory Study

详细信息    查看全文

• 作者：Hui He ; Yinkai Lei ; Chan Xiao ; Deryn Chu ; Rongrong Chen ; Guofeng Wang
• 刊名：The Journal of Physical Chemistry C
• 出版年：2012
• 出版时间：August 2, 2012
• 年：2012
• 卷：116
• 期：30
• 页码：16038-16046
• 全文大小：493K
• 年卷期：v.116,no.30(August 2, 2012)
• ISSN：1932-7455

文摘

Transition-metal (TM) macrocyclic complexes have potential applications as nonprecious electrocatalysts in polymer electrolyte membrane fuel cells. In this study, we employed density functional theory calculation methods to predict the molecular and electronic structures of O₂, OH, and H₂O₂ molecules adsorbed on TM porphyrins, TM tetraphenylporphyrins, TM phthalocyanines, TM fluorinated phthalocyanines, and TM chlorinated phthalocyanines (here TM = Fe or Co). Relevant to their performance on catalyzing oxygen reduction reaction (ORR), we found for the studied TM macrocyclic complexes: (1) The type of the central TM is the most determinant factor in influencing the adsorption energies of O₂, OH, and H₂O₂ (chemical species involved in ORR) molecules on these macrocyclic complexes. Specifically, the calculated adsorption energies of O₂, OH, and H₂O₂ on the Fe macrocyclic complexes are always distinguishably lower than those on the Co macrocyclic complexes. (2) The peripheral ligands are capable of modulating the binding strength among the adsorbed O₂, OH, and H₂O₂, and the TM macrocyclic complexes. (3) A N鈥揟M鈥揘 cluster structure (like N鈥揊e鈥揘) with a proper distance between the two ending N atoms and a strong electronic interaction among the three atoms is required to break the O鈥揙 bond and thus promote the efficient four-electron pathway of the ORR on the TM macrocyclic complexes.