Electronic Structure Modulation of AlN₄ Single-Atom Catalyst for Oxygen Reduction Reaction

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Mechanistic understanding of oxygen reduction reaction (ORR) in p-block metal single-atom catalysts (SACs) is limited.
• Aluminium (Al) typically shows poor ORR activity due to strong oxygen intermediate binding.

Purpose of the Study:

• To investigate the high intrinsic activity of AlN4 active sites in carbon nanostructures for ORR.
• To uncover the origins of catalytic activity in Al-based SACs through electronic structure analysis.

Main Methods:

• Comprehensive analysis of surface and bulk electronic structures.
• Theoretical calculations including Density Functional Theory (DFT) and Bader charge analysis.
• Fabrication and testing of Al-N4-C as cathode material in zinc-air batteries.

Main Results:

• Atomically dispersed AlN4 sites exhibit superior ORR activity, selectivity, and durability compared to macrocyclic aluminium phthalocyanine and Pt/C.
• Al-N4-C demonstrated stable performance over 36 hours in zinc-air batteries.
• Charge delocalization and local coordination environment are key factors for enhanced 4e- transfer ORR activity.

Conclusions:

• Tailoring the electronic structure and coordination environment of Al atoms optimizes the p-band center for enhanced ORR catalysis.
• Al-based SACs offer a viable alternative to precious metal catalysts for energy conversion applications.
• Findings provide insights for engineering main-group metal catalysts by tuning the p-band center.