Ultra-Small High-Entropy Alloy as Multi-Functional Catalyst for Ammonia Based Fuel Cells

Area of Science:

• Materials Science
• Electrochemistry
• Energy Conversion

Background:

• Ammonia fuel cells offer a carbon-free energy solution but are hindered by slow reaction kinetics.
• Platinum catalysts are effective but costly and prone to poisoning.
• Alloying platinum with other metals is a strategy to reduce cost and improve durability.

Purpose of the Study:

• To develop a cost-effective, multi-functional electrocatalyst for ammonia fuel cells.
• To investigate the performance of a novel high-entropy alloy catalyst for key fuel cell reactions.
• To assess the catalyst's durability and anti-poisoning properties.

Main Methods:

• Synthesis of platinum-iron-cobalt-nickel-iridium high-entropy alloy (HEA) nanoparticles on carbon support using Joule heating.
• Electrochemical characterization of the HEA catalyst for ammonia oxidation reaction (AOR), oxygen reduction reaction (ORR), and hydrogen evolution reaction (HER).
• Durability testing, including long-term stability and anti-poisoning assessments.

Main Results:

• The PtFeCoNiIr/C HEA catalyst demonstrated superior performance in AOR, ORR, and HER compared to commercial Pt/C.
• Achieved high peak current density for AOR (139.8 A g^-1 _PGM) and excellent ORR (E_1/2 = 0.87 V) and HER (E₁₀ = 20.3 mV) activity.
• Exhibited remarkable stability with no loss in HER performance over 200 hours and maintained ORR activity in anti-poisoning tests.

Conclusions:

• The developed PtFeCoNiIr/C HEA catalyst is a highly efficient and durable trifunctional electrocatalyst for ammonia fuel cells.
• This research paves the way for multi-functional electrocatalyst development and cost-effective fuel cell designs.
• The catalyst shows significant potential for practical applications in ammonia-powered fuel cells.