Tandem Catalysis Driven by Nitrogen Spillover in a Core-Shell Heterostructure for Direct Ammonia Fuel Cells.

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Low-temperature direct ammonia fuel cells (DAFCs) show promise but face challenges with slow ammonia oxidation reaction (AOR) kinetics and catalyst poisoning.
• Efficient catalysts are crucial for overcoming these limitations in DAFCs.

Purpose of the Study:

• To design and investigate a novel core-shell heterostructure catalyst for improved AOR performance in DAFCs.
• To address catalyst poisoning and enhance the kinetics of ammonia oxidation.

Main Methods:

• Fabrication of a vertically aligned NiCo2O4@NiCo2S4 core-shell heterostructure.
• Characterization of the catalyst's structure and electrochemical performance in a three-electrode system.
• Analysis of the catalytic mechanism, including *N spillover and work function engineering.

Main Results:

• The NiCo2O4@NiCo2S4 catalyst demonstrated a high current density of 972 mA cm-2 at 80 °C.
• The catalyst exhibited excellent stability for 20 hours, indicating poison tolerance.
• The core-shell structure and heterointerface facilitated a refined tandem catalytic pathway (NH3-*N-N2).

Conclusions:

• The developed NiCo2O4@NiCo2S4 heterostructure offers a novel and effective strategy for high-performance, poison-tolerant AOR anodes in DAFCs.
• The catalyst design optimizes electron configuration and promotes efficient *N spillover, enhancing catalytic activity and stability.