Ultrathin Ultralow-Platinum Catalyst Coated Membrane for Proton Exchange Membrane Fuel Cells

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Proton exchange membrane fuel cells (PEMFCs) rely on catalyst coated membranes (CCMs) for operation.
• Conventional CCM fabrication involves spraying platinum on carbon (Pt/C) slurries, leading to thick catalyst layers (CLs) with high platinum loading and mass transfer resistance.
• There is a critical need for highly active, ultrathin, and ultralow-platinum catalyst layers (UUCLs) to improve PEMFC efficiency and reduce costs.

Purpose of the Study:

• To develop an integrated ultrathin ultralow-platinum catalyst coated membrane (UUCCM) with significantly reduced platinum loading and enhanced performance.
• To investigate a novel wet-chemical direct growth method for fabricating UUCLs on both sides of a membrane.
• To understand the structure-activity relationship and the underlying mechanisms for the enhanced performance of the developed UUCCMs.

Main Methods:

• Wet-chemical direct growth of interconnected palladium (Pd) nanoneedle clusters on a membrane, initiated by proton release.
• High-density deposition of platinum nanoparticles (Pt NPs) onto the Pd nanoneedle clusters to form Pt/Pd UUCLs.
• Characterization of the UUCCM structure, including CL thickness and Pt loading, and evaluation of single-cell performance.

Main Results:

• Fabrication of integrated UUCCMs with an ultrathin cathodic CL thickness of 79.7 ± 15.0 nm and a low Pt loading of 20.2 ± 1.6 µg cm⁻².
• Achieved the highest reported mass peak power density of 59.9 W mg_Pt,Cathode⁻¹ in the literature for a single cell utilizing UUCCMs.
• Demonstrated exceptional activity attributed to high electrochemically active surface area, enhanced oxygen reduction reaction (ORR) activity influenced by strain and electronic effects at the Pt/Pd interface, and improved mass transport and water management.

Conclusions:

• The novel wet-chemical direct growth method enables the fabrication of highly efficient UUCCMs, overcoming limitations of conventional CCMs.
• The developed Pt/Pd UUCLs offer a promising pathway towards cost-effective and high-performance proton exchange membrane fuel cells.
• The findings highlight the importance of nanostructure design and interfacial engineering for advanced catalyst development in fuel cell technology.