Exploration of Oxygen Reduction Reaction Catalyzed by FePPc and Pz-FeTPr Conjugated Organic Polymer: Insights From Grand-Canonical Density Functional Theory.

ABSTRACT: This report examines the oxygen reduction reaction (ORR) catalyzed by iron-polyphthalocyanine (FePPc) and pyrazine-linked iron-coordinated tetrapyrrole (Pz-FeTPr) conjugated organic polymer (COP) catalysts, utilizing grand-canonical density functional theory (GC-DFT) and microkinetic (MK) simulations. The computed half-wave potential for AA stacking FePPc under alkaline conditions is in strong agreement with experimental findings. The ORR mechanism for AA stacking FePPc is characterized by the ^*O₂ mechanism ( O2→∗O2→∗OOH→∗O→∗OH→H2O${{\rm{O}}_2} \to ^*{O_2} \to ^*OOH \to ^*O \to ^*OH \to {H_2}O$ ), with the Fe site serving as the active site. In the case of Pz-FeTPr, the ORR mechanism is similarly governed by the ^*O₂ mechanism, with the Fe site remaining the active site at lower potentials (less than 0.5 V_RHE, vs reversible hydrogen electrode). However, at higher potentials (greater than 0.5 V_RHE), the Fe site becomes obstructed by O2-$O_2^ - $ , resulting in a shift of the active site from the Fe site to a neighboring C site (designated as type A3). The corresponding ORR mechanism at the C site is denoted as O2-$O_2^ - $ mechanism ( O2→O2-→∗O2-→∗OOH→∗O→∗OH→H2O${{\rm{O}}_2} \to O_2^ - \to ^*O_2^ - \to {\rm{^*OOH}} \to {\rm{^*O}} \to {\rm{^*OH}} \to {{\rm{H}}_2}{\rm{O}}$ ). This mechanism yields a calculated half-wave potential that aligns well with experimental observations. The mechanisms identified for FePPc and Pz-FeTPr can be substantiated by the Raman signals detected in experimental studies.

SUBMITTER: Yuan P 

PROVIDER: S-EPMC12376655 | biostudies-literature | 2025 Aug

REPOSITORIES: biostudies-literature