|
|
Faculty Member Name: Robert Walker
Title: Associate Professor; Assiciate Chair, Chemical Physics Program
Department: Chemistry and Biochemistry
College: Chemical and Life Sciences
Personal Web Page: www.chem.umd.edu/groups/walker/wrghome.html
E-mail
Telephone Number: 301.405.8667
Statement of energy interests and expertise:
Energy-related research in the Walker Groups focuses on developing optical spectroscopies to probe the surface chemistry occurring in operating solid-oxide fuel cells (SOFCs) and then using these methods to test experimentally different mechanisms proposed to describe fuel oxidation. SOFCs rely upon oxide transport across a solid oxide electrolyte, a process requiring temperatures in excess of 650?C in traditional units. Electrochemical techniques can be used to characterize cell performance as a function of fuel identity, fuel flows and cell potential, but these methods lack the ability to chemically identify intermediate species present on the anode, electrolyte and three phase boundary. Raman spectroscopy stands out as an ideal tool for studying electrochemical oxidation non-invasively and in-situ during SOFC operation. Despite numerous challenges, we have succeeded in using Raman spectroscopy to probe the surfaces of SOFCs at temperatures up to 1000K. These experiments have enabled us to follow the reversible oxidation/reduction of nickel-based anodes as well as the build-up and disappearance of graphitic carbon as a function of fuel speciation and cell potential. When coupled to the results of ex-situ measurements of SOFC exhaust, data from these studies have allowed us to identify the fates of fuels when they enter the SOFC anode chamber and comment on relative efficiencies of different fuels to oxidize or form ordered/disordered carbon on the SOFC anode. Furthermore, our experimental rig can be used to map the distribution and type of carbon being deposited on the SOFC anode assembly, thereby providing information about those components of anode architecture most susceptible to poisoning and failure. |
