Research in the Martin laboratory focuses on taking vibrational spectroscopy measurements at both [1] gas-solid and [2] solid-solid interfaces. These measurements are made through the use of a polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS) system. IRRAS with a Fourier transform infrared (FT-IR) spectrometer has sufficient sensitivity to measure films of thicknesses less than 200 nm.i,ii. In addition to this sensitivity, advantages of IRRAS include non-destructive interrogation of the sample by the IR probe, high spectral resolution of the FT-IR spectrometer, and a range of possible temperature and pressure conditions during experiments allowing for in situ measurements.iii
[1] Measurements of gas molecules on metal surfaces.
My research group uses in situ optical spectroscopic measurements of the anode of Solid Oxide Fuel Cells (SOFCs) under operating conditions to identify the rate-limiting steps and reaction mechanisms of the fuels’ electrochemical oxidation. SOFCs are more efficient than combustion engines, with approximate efficiencies of 75% and 10-30%, respectively. A fuel cell is similar to a combustion engine in that it is a refuelable energy conversion device; however, these cells generate heat and electricity from the electrochemical conversion of the fuel, rather than the relatively inefficient combustion step. Currently SOFC technology is very expensive, with the catalysts often being the most expensive component. Understanding the microscale electrochemistry and catalytic chemistry would significantly aid in the optimization of the macroscale performance of a given SOFC system, reducing the cost per kW and making SOFCs more attractive options to be implemented as part of a sustainable energy portfolio.
[2] Characterization of polymer thin-films.
Working in collaboration with the Hanks and Wright research groups, we will characterize poly(3,4-ethylenedioxythiophene) PEDOT)/alignate composites. These materials show great promise for use in tissue reconstruction, as interfaces between electronic devices and cells, and as sensors. The characterization of polymer thin-films adsorbed on metal surfaces, formed by either spin-coating or using a dip-coater, is difficult due to the small amount of material present and the presence of the metal substrate. The PM-IRRAS signal provides a direct probe of the absorption properties of the ultra-thin films, down even to sub-monolayer thicknesses, and is an excellent tool for characterizing polymer thin films on metal surfaces. PM-IRRAS probes the thickness, composition, conformation, and orientation of polymer films on metal surfaces.