Argonne National Laboratory

Upcoming Events


CSE Colloquium
Johna Leddy, University of Iowa
April 1, 2014 11:00AM to 12:00PM
Building 205, Y-Wing Auditorium
Electrons have properties of spin and charge. To transfer the electron, both the spin and the charge must transfer. Spin interacts with magnetic fields. Introduction of magnetic fields increases rates of electron transfer. Chemically and electrochemically inert micromagnets on electrodes surfaces increase currents for academically interesting redox probes and across a variety of electrochemical energy systems.

A model for magnetic effects on electron transfer reactions is derived based on temperature data for academically interesting redox probes. Current increases with the magnetic properties of the probe (gS, product of g-value and spin) and the strength of the magnetic field or intensity, B. Magnetic effects are largest in systems of high concentration and slow transport, such as reactions of adsorbates. For reactions of hydrogen, such as hydride storage and the hydrogen evolution reaction (HER), micromagnets increase rates substantially at electrodes traditionally viewed as non-electrocatalytic.

Reduction of carbon monoxide (CO) on Pt is rendered near diffusion limited. Micromagnets increase rates in reactions in electrochemical energy systems. This includes alkaline batteries and electrodes, Ni(OH)2 NiOOH electrodes, magnetically modified p-Si photocathodes, and PEM fuel cells. For electrodes, current enhancements of several fold are found; for complete electrochemical systems, enhancements of 40% are common. Magnetoelectrocatalysis is well effected by micromagnets on electrodes.

About the Presenter:
Professor Leddy is on the editorial boards for the following journals: The Journal of the Electrochemical Society, ECS Journal of Solid State Science and Technology, ECS Electrochemistry Letters, ECS Solid State Letters, ECS Transactions, and Critical Reviews in Analytical Chemistry. Leddy has also served on several review panels for the National Science Foundation that include fuel cells. Professor Leddy has been elected to offices in the Electrochemical Society and the Society for Electroanalytical Chemistry.