p-Block Tin Single-Atom Catalysts with Tuned p-Orbital State for Oxygen Reduction Reaction

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Single-atomic p-block main-group metal catalysts are explored for oxygen reduction reaction (ORR).
• Current catalysts face limitations due to difficulties in tuning electronic structures for optimal intermediate adsorption.
• Achieving efficient ORR catalysis requires precise control over metal-nitrogen coordination environments.

Purpose of the Study:

• To design and synthesize a highly efficient main-group single-atom catalyst (SAC) for ORR.
• To investigate the electronic structure modifications of tin (Sn) within a graphene derivative support.
• To establish a new design strategy for non-precious metal SACs.

Main Methods:

• Density functional theory (DFT) calculations guided catalyst design.
• Synthesis of a tin-nitrogen-doped graphene derivative (Sn-N-GDY) catalyst using an anhydrous method.
• Electrochemical evaluation of the Sn-N-GDY catalyst for ORR in alkaline media and zinc-air batteries.

Main Results:

• The Sn-N-GDY catalyst features Sn single atoms coordinated with pyrrolic and sp-hybridized nitrogen atoms.
• DFT calculations predicted and experimental results confirmed that N-doping modulates Sn 5p states, reducing adsorption energy for ORR intermediates.
• The catalyst achieved a half-wave potential (E1/2) of 0.86 V for ORR and demonstrated remarkable stability (1,147 h at 2 mA cm-2) in zinc-air batteries.

Conclusions:

• The Sn-N-GDY catalyst represents a significant advancement in main-group SACs for ORR.
• The study provides a viable design strategy for efficient, non-precious metal ORR catalysts.
• This work paves the way for new paradigms in catalyst development for electrochemical energy conversion.