Engineers from the University of Illinois Chicago are part of a group that has created a material that might provide fuel cell systems with a competitive advantage over the battery systems that now fuel most electric vehicles.
Photo by Andrew Roberts on Unsplash. Image Credit: University of Illinois Chicago.
Fuel cell technology, unlike lithium batteries, generates energy through catalyst-driven chemical processes. Lithium batteries can often go 100-300 miles on a single charge, but they are also susceptible to the high cost of cathode materials and production, and charging takes several hours.
Fuel cell systems, on the other hand, use plentiful components like oxygen and hydrogen to go over 400 miles on a single charge, which only takes about five minutes. Unfortunately, the catalysts they employ to fuel their reactions are comprised of elements that are either too costly (such as platinum) or degrade too rapidly to be useful.
That is, until now. Researchers can improve the durability of an affordable iron-nitrogen-carbon fuel cell catalyst by developing a new additive material. The additive substance shields fuel cell systems from two of the most corrosive byproducts of chemical reactions: unstable particles, such as atoms, molecules or ions known as free radicals, and hydrogen peroxide.
The results of their research were published in the scientific journal Nature Energy.
Reza Shahbazian-Yassar, a professor of mechanical and industrial engineering at the University of Illinois at Chicago, and coworkers investigated the interactions with the substance, a tantalum-titanium oxide nanoparticle additive that scavenges and deactivates free radicals using advanced imaging techniques.
The scientists were able to identify the structural characteristics required for the additive to operate thanks to high-resolution imaging of atomic structures.
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.
Reza Shahbazian-Yassar, Study Co-Corresponding Author and Professor, Mechanical and Industrial Engineering, University of Illinois Chicago
Shahbazian-Yassar added, “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 found that a solid tantalum and titanium oxide solution is required, with nanoparticles measuring roughly five nanometers. The investigations also demonstrated that a tantalum-to-titanium oxide ratio of 6-4 is necessary.
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.
Reza Shahbazian-Yassar, Study Co-Corresponding Author and Professor, Mechanical and Industrial Engineering, University of Illinois Chicago
When the scavenger nanoparticle material was introduced to the reactions of fuel cell systems, hydrogen peroxide output was decreased to less than 2% — a 51% reduction — and the current density decaying of fuel cells was reduced from 33% to just 3%, according to the research.
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. 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, Study Co-Corresponding Author and Professor, Mechanical and Industrial Engineering, University of Illinois Chicago
Abhijit Phakatkar of UIC and co-corresponding authors Guoxiang Hu of Queens College of the City University of New York, Yuyan Shao of Pacific Northwest National Laboratory, and Liangbing Hu of the University of Maryland co-authored the paper titled “Ta–TiOx nanoparticles as radical scavengers to improve the durability of Fe–N–C oxygen reduction catalysts.”
Hua Xie, Xiaohong Xie, Venkateshkumar Prabhakaran, Sulay Saha, Lorelis Gonzalez-Lopez, Min Hong, Meiling Wu, Vijay Ramani, Mohamad Al-Sheikhly, and De-en Jiang are among the other co-authors.
The research was funded by the US Department of Energy, the National Science Foundation, and the Maryland Nanocenter.
Journal Reference:
Xie, H., et al. (2022) Ta–TiOx nanoparticles as radical scavengers to improve the durability of Fe–N–C oxygen reduction catalysts. Nature Energy. doi.org/10.1038/s41560-022-00988-w.