Fundamental Understanding of Electronic Structure in FeN4 Site on Electrocatalytic Activity via dz2‐Orbital‐Driven Charge Tuning for Acidic Oxygen Reduction. Issue 16 (6th March 2023)

• Record Type: Journal Article
• Authors: Li, Xueli; Chen, Tengge; Yang, Bolong; Xiang, Zhonghua
• Is Part Of: Angewandte Chemie international edition. Volume 62:Issue 16(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2023-03-06
• Subjects: Acidic ORR Performance -- FeN4 Moiety -- Local Coordination Environment -- Pyrolysis-Free Strategy -- d-π Conjugation Hybridization; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.202215441
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: The structural diversity of active sites resulting from traditional pyrolysis hinder our understanding of the local coordination environment (LCE) around the active site, and its effects on performance in the oxygen reduction reaction (ORR). We created a series of FeN4 active‐site configurations via a pyrolysis‐free approach where LCEs are defined by covalent organic polymers (COPs). Our results suggest a more positive charge on iron atoms in the vicinity of an electron‐withdrawing side‐chain; that is, a high‐valence configuration (Fe H+ N4 ) that is achieved with a COPBTC @Cl‐CNTs catalyst subject to d z 2 ${{d}_{{z}^{2}}}$ ‐orbital tuning. A new descriptor ξ, defined as the band center of iron atoms projected on the 3 d z 2 ${{3d}_{{z}^{2}}}$ ‐orbital, was introduced to quantitively explain a volcano‐like regulation mechanism. When ξ is distributed between −1.887 and −1.862 eV, the catalytic performance of the COPBTC @Cl‐CNTs electrocatalyst is optimized. Abstract : We present a fundamental perspective on the electron structure of the FeN4 site on the acidic oxygen reduction reaction activity of a COPBTC @Cl‐CNTs catalyst integrated into a proton exchange membrane fuel cell. Via d z 2 ${{d}_{{z}^{2}}}$ ‐orbital‐driven charge tuning, the performance of the fuel cell is improved by an order of magnitude compared with that of an untuned FeN4 catalyst.