“In this paper, we report on an approach that gets us much closer to making fuel-cell-powered vehicles and other fuel cell technologies a reality.”Reza Shahbazian-Yassar, University of Illinois at Chicago
Engineers at the University of Illinois at Chicago (UIC) are part of a collaborative team that has developed a material that could give fuel cell systems a competitive edge over the battery systems that currently power most electric vehicles.
In contrast to lithium batteries, fuel cell technology relies on catalyst-driven chemical reactions to create energy. The lithium batteries used in electric vehicles can typically achieve a range of 100–300 miles on one charge, but they are vulnerable to the high cost of cathode materials and manufacturing and require several hours to charge.
Fuel cell systems, by contrast, take advantage of abundant elements such as oxygen and hydrogen and can achieve more than 400 miles on a single charge – which can be done in under five minutes. Unfortunately, the catalysts used to power the reactions in fuel cells are made of materials that are either too expensive (i.e., platinum) or too quickly degraded to be practical.
Until now, that is, thanks to the development of a new additive material comprised of tantalum-titanium oxide nanoparticles, which can make an inexpensive iron-nitrogen-carbon fuel cell catalyst more durable. It does this by scavenging and deactivating free radicals and hydrogen peroxide, which are two of the most corrosive by-products of the chemical reactions that take place in fuel cells. The engineers report their advance in a paper in Nature Energy.
Reza Shahbazian-Yassar, professor of mechanical and industrial engineering at the UIC College of Engineering, and colleagues used advanced imaging techniques to investigate reactions with the additive material. This high-resolution imaging of the atomic structures allowed the scientists to define the structural parameters needed for the additive to work.
“In our lab, we are able to use electron microscopy to capture highly detailed, atomic-resolution images of the materials under a variety of service conditions,” said study co-corresponding author Shahbazian-Yassar. “Through our structural investigations, we learned what was happening in the atomic structure of additives and were able to identify the size and dimensions of the scavenger nanoparticles, the ratio of tantalum and titanium oxide. This led to an understanding of the correct state of the solid solution alloy required for the additive to protect the fuel cell against corrosion and degradation.”
These experiments revealed that a solid solution of tantalum and titanium oxide is required and that the nanoparticles should be around 5nm in size. They also revealed that a six-to-four ratio of tantalum to titanium oxide is required.
“The ratio is the key to the radical scavenging properties of the nanoparticle material and the solid-state solution helped sustain the structure of the environment,” Shahbazian-Yassar said.
When the scavenger nanoparticle material was added to fuel cell systems, the researchers found that the hydrogen peroxide yield was suppressed to less than 2% – a 51% reduction – and the current density decay was reduced from 33% to only 3%.
“Fuel cells are an attractive alternative to batteries because of their higher driving range, fast recharging capabilities, lighter weight and smaller volume, provided that we can find more economical ways to separate and store hydrogen,” Shahbazian-Yassar said. “In this paper, we report on an approach that gets us much closer to making fuel-cell-powered vehicles and other fuel cell technologies a reality.”
This story is adapted from material from the University of Illinois at Chicago, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.