Dynamic Control of Sacrificial Bond Transformation in the Fe−N−C Single‐Atom Catalyst for Molecular Oxygen Reduction

Abstract

Atomically dispersed metal‐nitrogen sites show great prospect for the oxygen reduction reaction (ORR), whereas the unsatisfactory adsorption‐desorption behaviors of oxygenated intermediates on the metal centers impede improvement of the ORR performance. We propose a new conceptual strategy of introducing sacrificial bonds to remold the local coordination of Fe−Nx sites, via controlling the dynamic transformation of the Fe−S bonds in the Fe−N−C single‐atom catalyst. Spectroscopic and theoretical results reveal that the selective cleavage of the sacrificial Fe−S bonds induces the incorporation of the electron‐withdrawing oxidized sulfur on the Fe centers. The newly functionalized moieties endow the catalyst with superior ORR activity and remarkable stability, owing to the reduced electron localization around the Fe centers facilitating the desorption of ORR intermediates. These findings provide a unique perspective for precisely controlling the coordination structure of single‐atom materials to optimize their activity.

Tailoring the selectivity and activity of oxygen reduction by regulating the coordination environments of carbon-supported atomically dispersed metal sites

“…75 An identical effect also gained acceptance when Ruan et al proposed a sacrificial bond transformational strategy to selectively cleave Fe–S bonds in the Fe–N–C single atom catalyst to construct the Fe–O–S bond and remold the local coordination. 111 Theoretical results revealed that compared with the Fe–N 3 S site, more electrons withdraw from the centers across the Fe–O–S interface in addition to Fe–N interaction, optimizing the adsorption–desorption strength of oxygenated intermediates to facilitate the 4e − pathway on the Fe–N 3 O–S site. Li et al developed N and P doped Fe–N 4 catalysts with robust ORR efficiency.…”

“…Besides, exotic atoms doped in other coordination shells can have a signicant impact on long-range electronic delocalization and interaction. So, in this section, we rst discuss (111), respectively. The free energy diagram of three different potentials is exhibited: 0 V RHE (blue lines), the corresponding equilibrium potential (green lines), and the limiting potential (black lines).…”

Using Computational Chemistry To Reveal Nature’s Blueprints for Single-Site Catalysis of C–H Activation

“…Various experimental characterization techniques have been used to investigate SAC structures and reactivity, especially in the case of iron. For example, the properties of Fe are characterized by 57 Fe Mössbauer spectroscopy, , X-ray absorption near-edge spectroscopy (XANES), and EXAFS. , High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) , is frequently utilized to confirm that metals are atomically dispersed in SACs. These spectroscopic analyses suggest that the support and primary coordination sphere are essential in determining catalytic reactivity, , consistent with conclusions drawn from DFT simulations. , Joint experimental characterization and computational studies have highlighted the roles of the support and primary coordination sphere for SACs in catalyzing HER, ORR, − CO 2 RR, ,, and selective C–H bond oxidation. , …”

“…For example, the properties of Fe are characterized by 57 Fe Mossbauer spectroscopy, 206,207 X-ray absorption near-edge spectroscopy (XANES), and EXAFS. 208,209 High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) 210,211 is frequently utilized to confirm that metals are atomically dispersed in SACs. These spectroscopic analyses suggest that the support and primary coordination sphere are essential in determining catalytic reactivity, 212,213 consistent with conclusions drawn from DFT simulations.…”

Vicinal Co atom-coordinated Fe–N–C catalysts to boost the oxygen reduction reaction

“…, Fe–N 4 site), boosting the catalytic activity. For instance, Ruan 30 et al reported that the neighboring oxidized-S reduced electron localization around the Fe atoms, contributing to the desorption of the ORR intermediates from the Fe centers. Therefore, the establishment of a reasonable vicinal structure of the Fe–N 4 sites would be an ideal strategy to enhance the electrochemical durability in ORR catalysis.…”