(Figure 1. Electrode structure for the precise evaluation of the metal nanoparticles’ electrochemical catalytic characteristics at a high temperature.)
A KAIST team presented an ideal electrode design to enhance the performance of high-temperature fuel cells. The new analytical platform with advanced nanoscale patterning method quantitatively revealed the electrochemical value of metal nanoparticles dispersed on the oxide electrode, thus leading to electrode design directions that can be used in a variety of eco-friendly energy technologies.
The team, working under Professor WooChul Jung and Professor Sang Ouk Kim at the Department of Materials Science and Engineering, described an accurate analysis of the reactivity of oxide electrodes boosted by metal nanoparticles, where all particles participate in the reaction. They identified how the metal catalysts activate hydrogen electro-oxidation on the ceria-based electrode surface and quantify how rapidly the reaction rate increases with the proper choice of metals.
Metal nanoparticles with diameters of 10 nanometers or less have become a key component in high-performance heterogeneous catalysts, primarily serving as a catalytic activator. Recent experimental and theoretical findings suggest that the optimization of the chemical nature at the metal and support interfaces is essential for performance improvement.
However, the high cost associated with cell fabrication and operation as well as poorer stability of metal nanoparticles at high temperatures have been a long-standing challenge. To solve this problem, the team utilized a globally recognized metal nano patterning technology that uses block copolymer self-assembled nano templates and succeeded in uniformly synthesizing metal particles 10 nanometers in size on the surface of oxide fuel cell electrodes. They also developed a technology to accurately analyze the catalyst characteristics of single particles at high temperatures and maximize the performance of a fuel cell with minimal catalyst use.
The research team confirmed that platinum, which is a commonly used metal catalyst, could boost fuel cell performance by as much as 21 times even at an amount of 300 nanograms, which only costs about 0.015 KRW.
The team quantitatively identified and compared the characteristics of widely used metal catalysts other than platinum, such as palladium, gold, and cobalt, and also elucidated the precise principle of catalyst performance through theoretical analysis.
(Figure 2. Comparison of the electrochemical catalytic characteristics for various 10nm metal nanoparticles (platinum, palladium, cobalt, gold) at a high temperature.)
Professor Jung said, "We have broken the conventional methods of increasing the amount of catalyst which have deemed inefficient and expensive. Our results suggest a clear idea for high performance fuel cells using very small amounts of nanoparticles. This technology can be applied to many different industrial fields, advancing the commercialization of eco-friendly energy technologies such as fuel cells that generate electricity and electrolytic cells that produce hydrogen from water.”
The research has been published as the cover article of Nature Nanotechnology in the March issue. This research was carried out with support from the Nano-Material Technology Development Program through the National Research Foundation of Korea.