• A durable oxide support, macroporous Nb–SnO₂, was developed as an alternative to conventional carbon supports.
• By employing a flame-assisted spray-drying process, macropores on the order of several hundred nanometers were introduced into the particles.
• The porous structure was preserved even after catalyst layer formation, leading to reduced gas diffusion resistance and an increase in maximum current density. 

The development of fuel cell technology, which directly converts the chemical energy of fuels such as hydrogen into electricity, is highly anticipated. In current polymer electrolyte fuel cells (PEFCs), carbon nanoparticles supporting platinum catalysts are widely employed. However, carbon is known to degrade under high-potential conditions, and the expansion of fuel cell applications to diverse mobilities such as trucks, buses, and ships requires the development of alternative support materials.

Metal oxides with high thermal and chemical stability have been investigated as alternatives to carbon supports. Nevertheless, their lack of highly developed porous structures, unlike carbon, has limited their catalytic performance.

To address this challenge, macroporous Nb-doped SnO₂ (NTO) particles were introduced as catalyst supports, offering a new material design concept that combines durability and power generation performance in PEFCs. The introduction of macropores on the scale of several hundred nanometers into NTO promoted gas diffusion and water removal within the catalyst layer, thereby reducing gas diffusion resistance and enhancing power generation performance. This outcome demonstrates a novel design principle for catalyst supports that unites the high durability of oxide materials with the excellent gas transport properties of carbon supports, paving the way toward next-generation durable and high-performance fuel cells.

This work has been published in the American Chemical Society journal Nano Letters. 

【Publication Details】
Tomoyuki Hirano*, Takama Tsuboi, Thi Thanh Nguyen Ho, Eishi Tanabe, Aoi Takano, Mikihiro Kataoka, and Takashi Ogi*, Macroporous Structures of Nb–SnO₂ Particle as a Catalyst Support Induce High Porosity and Performance in Polymer Electrolyte Fuel Cell Catalyst Layers, Nano Letters, 24(34), 10426-10433, 2024.