Insights into Co-Catalytic Single-Atom-Support Interactions for Boosting Sulfur Reduction Electrocatalysis

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Single-atom catalysts (SACs) are crucial for inhibiting the shuttle effect in lithium-sulfur (Li-S) batteries.
• The synergistic catalytic role of SACs and their supports in sulfur reduction reactions (SRR) remains underexplored.

Purpose of the Study:

• To elucidate the co-catalytic mechanism of Cobalt SACs supported on graphitic carbon nitride (Co-GCN) for enhancing SRR.
• To investigate the interactions between Co-SACs, the GCN support, and lithium polysulfides (LiPSs).

Main Methods:

• Density functional theory (DFT) calculations were employed to guide catalyst selection and mechanism elucidation.
• Co-GCN was synthesized and characterized for its structural and electronic properties.
• Electrochemical performance of Li-S batteries utilizing Co-GCN as a cathode additive was evaluated.

Main Results:

• GCN's high charge polarity and tri-s-triazine structure facilitate LiPS binding via Li-N bonds and anchor Co-SACs.
• The Co-GCN structure amplifies LiPS interaction through Co-S bonds, enabling dual participation of Co-SACs and GCN in SRR.
• The combined catalytic effect lowers the SRR energy barrier, leading to superior rate performance (718.9 mAh g⁻¹ at 5.0 C) and high areal capacity (13.8 mAh cm⁻² at 8.7 mg cm⁻² sulfur loading).

Conclusions:

• Co-GCN exhibits a unique synergistic effect that significantly enhances SRR by actively binding LiPS intermediates.
• The study provides a mechanistic understanding of SAC-support interactions in Li-S batteries, paving the way for advanced catalyst design.
• The developed Co-GCN catalyst demonstrates excellent potential for high-performance Li-S batteries with high sulfur loading and low electrolyte ratios.