High Performance Palladium Supported on Nanoporous Carbon under Anhydrous Condition

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Polymer electrolyte fuel cells (PEFCs) are expensive due to platinum (Pt) catalyst reliance.
• Developing cost-effective alternatives is crucial for widespread PEFC adoption.
• High-temperature operation in PEFCs presents unique challenges for catalyst stability and performance.

Purpose of the Study:

• To synthesize and characterize a novel platinum-free electrocatalyst for high-temperature PEFCs.
• To optimize the catalyst composition and structure for enhanced performance and durability.
• To evaluate the potential of palladium nanoparticles (Pd-NPs) as a cost-effective alternative to platinum.

Main Methods:

• Palladium nanoparticles (Pd-NPs) were deposited on nanoporous carbon (NC).
• The NC support was wrapped with poly[2,2'-(2,6-pyridine)-5,5'-bibenzimidazole] (PyPBI) doped with phosphoric acid (PA).
• Catalyst size was controlled by varying the precursor to support ratio; membrane electrode assemblies (MEAs) were fabricated and tested.

Main Results:

• The optimized Pt-free catalyst (0.05 mgPd cm⁻²) achieved a power density of 76 mW cm⁻² at 120°C without humidification.
• This performance is comparable to commercial Pt catalysts (0.45 mgPt cm⁻²), which yielded 89 mW cm⁻².
• A hybrid MEA with Pt cathode and Pd anode reached 188 mW cm⁻², demonstrating synergistic effects.

Conclusions:

• The Pt-free Pd-NP electrocatalyst shows significant promise for reducing high-temperature PEFC costs.
• The porous structure and PyPBI-PA matrix enhance gas diffusion and proton conductivity, respectively.
• The polymer coating improves the durability of the palladium catalyst, making it suitable for demanding applications.