Molecular electrocatalysis of oxygen reduction by iron(II) phthalocyanine at the liquid/liquid interface

• Published in: Journal of electroanalytical chemistry (Lausanne, Switzerland) Vol. 766; pp. 37 - 43
• Main Authors: Xuan, Yaofang, Xie, Lisiqi, Huang, Xiao, Su, Bin
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.04.2016
• Subjects: Biphasic reaction; Catalysis; Iron(II) phthalocyanine; Liquid/liquid interface; O2 reduction; Biphasic reaction; Iron(II) phthalocyanine; Liquid/liquid interface; Catalysis; O2 reduction
• ISSN: 1572-6657; 1873-2569
• DOI: 10.1016/j.jelechem.2016.01.028

Liquid/liquid interface electrochemistry has manifested itself as a good approach to study oxygen reduction reaction (ORR) and ORR catalyzed by various catalysts. In this work, we investigated the ORR catalyzed by iron(II) phthalocyanine (FePc), which has a structure similarity to the heme group of O2-binding proteins and reducing enzymes, at the polarized water/1,2-dichloroethane interface. Using the four-electrode cyclic voltammetry and the shake-flask biphasic reaction under chemically controlled polarization, it was demonstrated that FePc could catalyze the molecular oxygen reduction by lipophilic electron donors, such as 1,1′-dimethylferrocene (DFc) or tetrathiafulvalene (TTF), at the heterogeneous phase boundary. The overall process essentially can be equivalent to an interfacial proton transfer coupled ORR, which proceeds preferentially via a four electron reduction pathway to produce mainly H2O with only minority of H2O2 (less than 5%). The catalytic activity of FePc was compared with all previously studied porphyrins and phthalocyanines. The reaction mechanism was also analyzed, in which a hydroperoxo intermediate was probably involved. [Display omitted] •ORR catalyzed by iron(II) phthalocyanine was studied at the liquid/liquid interface.•The catalytic O2 reduction mainly produces H2O with only minority of H2O2 (less than 5%).•The reaction possibly involves a hydroperoxo intermediate.