ChBE Seminar Series: Jonah Erlebacher
Tuesday, October 11, 2016
Room 2108, Chemical and Nuclear Engineering Building
Dept. Chair & Professor
MSE, Johns Hopkins University
Recent Insights into Electrocatalysis using Dealloyed Nanoporous Metal
Automotive fuel cells powered by hydrogen hold the promise of highly energy efficient and clean transportation. Fuel cells trick the hydrogen oxidation reaction (aka burning) into releasing energy in the form of electrical power, rather than heat. But to get this reaction going in a fuel cell requires expensive catalysts based on platinum, and there are concerns whether platinum-based catalysts will ever be good enough (in the sense that a car can be made with less Pt than currently is used in cars, about 5 g/vehicle). Of particular concern are catalysts for the oxygen reduction reaction (ORR), which combines oxygen, protons and electrons to form water, and alone accounts for the majority of energy efficiency loss in proton exchange membrane fuel cells.
In this presentation, I will describe the current state-of-the-art with regards to platinum-based catalysts for automotive applications and discuss how this technology can be moved forward by understanding the fundamental stability and catalytic mechanisms in transition metal + platinum alloy catalysts. Here, the corrosion process known as dealloying plays a central role. In dealloying, one component of a two-component alloy is dissolved away under conditions in which the remaining component re-organizes into a three-dimensional nanoporous metal. Dealloyed Ni/Pt particles are some of the most active catalysts for the ORR, and porosity adds another dimension to catalyst design. By filling the pores with ionic liquids that create a microenvironment that biases the ORR to completion, we can magnify the ORR activity of the base catalyst, leading to even higher activities. This strategy has led to the development of fuel cell catalysts that hold the promise of vehicles utilizing less than even a gram of Pt per car, and I will discuss how we are generalizing this concept to applications in other important energy-related chemical reactions.
More About the Speaker:
Jonah Erlebacher is Professor and Chair of the Department of Materials Science and Engineering at Johns Hopkins University, and sits on the Advisory Board of the ACS Petroleum Research Fund. Erlebacher’s general research interests include self-organization and pattern formation as a way to create nanostructured materials, with a particular emphasis on applications of these materials for energy technologies. His approach employs both computational and experimental methods. Erlebacher received his B.S. degree from Yale University in 1991 in Physics and History of Art, and received a PhD under Michael J. Aziz at Harvard University in 1999. He joined the faculty of Johns Hopkins University in 2000.