Breathing new life into fuel cells

However, fuel cells are held back by sluggish kinetics in a part of the core chemical reaction that limits efficiency. But, researchers from The University of Texas at Austin have discovered new dynamics that could supercharge this reaction using iron-based single-atom catalysts.

The researchers developed a new method to improve the oxygen reduction portion of the chemical reaction in fuel cells, in which O2 molecules are split to create water. They did so through a "hydrogel anchoring strategy" that creates densely packed sets of iron atoms held in place by a hydrogel polymer. Finding the right formula for spacing these atoms created interactions that allowed them to morph into catalysts for oxygen reduction.

Figuring out the density and locational dynamics of these iron atoms unlocks a level of efficiency in this reaction never before realized. The researchers demonstrated these findings in a new paper published recently in Nature Catalysis.

The oxygen reduction reaction is perhaps the greatest impediment to large-scale deployment of fuel cells. The promise of fuel cells lies in the fact that they are nearly limitless in potential applications. They can use a wide range of fuels and feedstocks to provide power for systems as large as a utility power station and as small as a laptop computer.

Academic researchers around the globe are working to enhance fuel cell capabilities. That includes other engineers at UT Austin who are taking a variety of approaches to solve key problems in fuel cell development.

"It is of the utmost importance to replace fossil fuels with clean and renewable energy sources to tackle major problems plaguing our society like climate change and the pollution of the atmosphere," said Guihua Yu, an associate professor of materials science in the Cockrell School's Walker Department of Mechanical Engineering. "Fuel cells have been regarded as a highly efficient and sustainable technology to convert chemical to electrical energy; however, they are limited by the sluggish kinetics of the cathodic oxygen reduction reaction. We found that the distance between catalyst atoms is the most important factor in maximizing their efficiency for next-generation fuel cells."

These findings can be applied to anything that includes electrocatalytic reactions. That includes other types of renewable fuels as well as ubiquitous chemical products such as alcohols, oxygenates, syngas and olefin.

In addition to Yu, authors include Zhaoyu Jin from UT's Texas Materials Institute and the Department of Chemistry; Panpan Li and Zhiwei Fang from the Texas Materials Institute, and Dan Xiao and Yan Meng from the Department of Chemical Engineering, Sichuan University in China. The team has spent more than two years working on this project, and it was funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences; the Welch Foundation; and the Camille Dreyfus Teacher-Scholar Award.