Graphene-based iron single-atom catalysts for electrocatalytic nitric oxide reduction: a first-principles study

Area of Science:

• Electrocatalysis
• Materials Science
• Sustainable Chemistry

Background:

• Electrocatalytic nitrogen oxide reduction reaction (NORR) offers a sustainable route to convert harmful NO into valuable NH3.
• Graphene-based Fe single-atom catalysts (SACs) show promise in electrocatalysis, but their NORR potential and mechanisms require further investigation.

Purpose of the Study:

• To systematically investigate the electrocatalytic NORR performance of graphene-based Fe SACs.
• To explore the underlying electronic structure and reaction mechanisms governing NORR activity and selectivity.
• To identify key descriptors for efficient Fe SAC design for NORR.

Main Methods:

• Density functional theory (DFT) calculations under constant potential.
• Construction and analysis of 26 different Fe SAC systems with varying coordination environments.
• Electronic structure analysis and d-band center calculations.

Main Results:

• Identified Fe SACs coordinated with four pyrrole N atoms and three pyridine N atoms with one O atom exhibit excellent NORR activity (limiting potentials of -0.26 and -0.33 V).
• These catalysts demonstrate high selectivity towards NH3 production, suppressing byproduct formation, particularly under applied potential.
• The electron 'donation-backdonation' mechanism facilitates NO adsorption and activation, with the d-band center identified as a descriptor for NORR activity.

Conclusions:

• Graphene-based Fe SACs are promising for efficient and selective electrocatalytic NO reduction to NH3.
• The coordination environment significantly influences catalytic performance, with specific configurations showing superior activity.
• The d-band center serves as a valuable descriptor for guiding the design of advanced Fe SACs for NORR.