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

作者：He Hui; Lei Yinkai; Xiao Chan; Chu Deryn; Chen Rongrong^*; Wang Guofeng

来源：Journal of Physical Chemistry C, 2012, 116(30): 16038-16046.

DOI：10.1021/jp303312r

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 O-2, 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 O-2, OH, and H2O2 (chemical species involved in ORR) molecules on these macrocyclic complexes. Specifically, the calculated adsorption energies of O-2, 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 O-2, OH, and H2O2, and the TM macrocyclic complexes. (3) A N-TM-N cluster structure (like N-Fe-N) 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-O bond and thus promote the efficient four-electron pathway of the ORR on the TM macrocyclic complexes.

• 出版日期2012-8-2