Entropy-Modulated Oxide-Metal Catalyst Architectures for Direct Ammonia Protonic Ceramic Fuel Cells | JoVE Visualize

Area of Science:

Materials Science and Engineering
Electrochemistry
Catalysis

Background:

Protonic ceramic fuel cells (PCFCs) offer a carbon-free energy pathway using ammonia (NH₃).
Conventional Ni-based anodes in PCFCs suffer from limited catalytic activity and degradation, hindering performance.
Developing advanced anode catalysts is crucial for efficient direct ammonia utilization in PCFCs.

Purpose of the Study:

To develop and evaluate a high-entropy perovskite catalyst for direct ammonia-fed PCFCs.
To investigate the catalytic mechanisms and performance enhancements offered by the novel catalyst.
To assess the stability and durability of PCFCs utilizing the new anode material.

Main Methods:

Synthesis of a high-entropy perovskite catalyst: Sr₂Fe₁Mo_0.2Mn_0.2Cr_0.2Cu_0.2Ni_0.2O_6-δ (SFMMCCN).
In situ characterization of the anode catalyst layer within direct ammonia-fed PCFCs.
Performance testing including power density and electrochemical impedance spectroscopy.
Long-term operational stability tests under ammonia fuel.
Density functional theory (DFT) calculations to elucidate catalytic mechanisms.

Main Results:

The SFMMCCN catalyst, upon reduction, exsolves active Ni-Fe-Cu alloy nanoparticles within a stable oxide matrix.
The SFMMCCN-based PCFC achieved a record peak power density of 2.04 W cm⁻² at 700 °C.
Exceptional operational stability was demonstrated, lasting over 255 hours at 600 °C under NH₃ fuel.
The catalyst significantly reduced polarization resistance and suppressed Ni coarsening compared to bare cells.
DFT calculations confirmed lower energy barriers for NH₃ decomposition over the high-entropy oxide-alloy structure.

Conclusions:

Entropy-controlled oxide-metal architectures, like the SFMMCCN catalyst, are highly effective for NH₃-fueled PCFCs.
The synergistic effect of the oxide matrix and exsolved alloy nanoparticles enhances catalytic activity and durability.
This approach provides a viable pathway for scalable and efficient hydrogen-based power generation using ammonia.
The developed catalyst overcomes limitations of conventional anodes, paving the way for advanced electrochemical systems.