Scavenger nanoparticles could advance fuel cell tech

Fuel cell technology relies on catalyst-driven chemical reactions to create energy. Lithium batteries can typically achieve a range of 100-300 miles on one charge, but are also vulnerable to the high cost of cathode materials and manufacturing, and require several hours to charge.

Alternatively, fuel cell systems 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. The catalysts used to power their reactions are made of materials that are either too expensive (e.g platinum) or too quickly degraded to be practical.

US scientists have now reportedly developed an additive material that allows for a more durable, inexpensive iron-nitrogen-carbon fuel cell catalyst.

When added to the chemical reactions, researchers said the additive material protects fuel cell systems from two of its most corrosive by-products: unstable particles like atoms, molecules or free radicals and hydrogen peroxide.

Reported in Nature Energy, the team’s work involved using advanced imaging techniques to investigate the reactions with the material, an additive comprised of tanatlum-titanium oxide nanoparticles that scavenge and deactivate the free radicals. 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 Reza Shahbazian-Yassar, professor of mechanical and industrial engineering at the UIC College of Engineering.

“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.”

Experiments revealed that a solid solution of tantalum and titanium oxide is required and that the nanoparticles should be around five nanometres. They also revealed that a 6-4 ratio of tantalum to titanium oxide is required. Shahbazian-Yassar said that the ratio was key to the radical scavenging properties of the nanoparticle material, and the solid-state solution helped sustain the environment’s structure.

When the scavenger nanoparticle material was added to the reactions of fuel cell systems, hydrogen peroxide yield was suppressed to less than two per cent — a 51 per cent reduction — and current density decay of fuel cells was reduced from 33 per cent to only three per cent, researchers confirmed.