New imaging shows fuel-cell’s secrets

New imaging shows fuel-cell’s secrets

Using a new technique known as aberration-corrected Scanning Transmission Electron Microscopy, researchers from the Massachusetts Institute of Technology, the University of Texas at Austin, and Oak Ridge National Laboratory have identified specific atomic structures near the surface of nanoparticles in a fuel cell’s platinum-cobalt catalyst.

The nanoparticles are known to catalyze some of the chemical reactions behind fuel cells, making those reactions run up to four times faster than if platinum alone is used, but no one understood exactly why. As a result of the imaging, the researchers are able to propose a theory for why the material is so active.

The researchers analyzed nanoparticles that were acid treated only and acid treated and subjected to high heat, both of which are known to be more active than platinum alone. Each type had slightly different surface structures, but both consisted of platinum atoms atop cobalt atoms.

The team proposes that the surface platinum atoms are constrained by the cobalt atoms underneath, which modifies the interatomic distances between the platinum atoms on the nanoparticle’s surface. This is thought to make the catalyst more effective in those chemical reactions key to fuel cells’ operation.

Team member Yang Shao-Horn, director of MIT’s Electrochemical Energy Laboratory, notes “this work bridges the gap between our understanding of electrocatalysis in bulk materials and at the nano-scale.” For more information, contact her at 617-253-2259, shaohorn@mit.edu

Richard Comerford