Identifying the active sites in unequal iron-nitrogen single-atom catalysts

Area of Science:

• Catalysis
• Materials Science
• Spectroscopy

Background:

• Single-atom catalysts (SACs) are crucial for energy conversion but their active sites are poorly understood due to ensemble-averaged measurements.
• Atomic heterogeneity in SACs conceals the specific roles of individual active sites in catalytic mechanisms.

Purpose of the Study:

• To develop a quantitative method for investigating single-atom catalysis at the molecular level.
• To elucidate the distinct catalytic properties and mechanisms of individual active sites in iron-nitrogen (Fe-N) coordinated SACs.

Main Methods:

• Developed single-atom catalysis-fluorescence correlation spectroscopy (SAC-FCS), a quantitative method based on single-molecule fluorescence microscopy.
• Leveraged atomic structure-dependent catalysis kinetics and single-turnover resolution to analyze oxidase-like catalysis.

Main Results:

• Quantified active sites and their kinetic parameters on unidentical Fe-N coordinated SACs.
• Demonstrated significant differences between individual active sites and average catalytic behaviors.
• Corroborated the oxidase-like catalytic mechanism of Fe-N active sites.

Conclusions:

• The SAC-FCS method provides essential insights into the heterogeneity of SACs.
• This technique facilitates the rational design and application of SACs by understanding individual active site functions.