MSE Seminar - Professor Jonah D Erlebacher - MSE - The Johns Hopkins University
Title: Are we there yet? Advanced catalysts for automotive fuel cells via electrochemical dealloying
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.
Reception at 3:30 pm in MARC Atrium