Proton Exchange Membrane Fuel Cells
I have developed wideline 195Pt NMR for the investigation of various Pt nanoparticle and PtSn intermetallic preparations used in industrial and autocatalyst roles. The catalytic activity of these materials is isolated to the surface or near-surface of these layers, away from the bulk metallic centre. A detailed deconvolution of the 195Pt broadline NMR data using a core-shell model enables an analysis of the proportion of reactive Pt sites able to be accessed in different nanoparticle sizes. To complete such a detailed analysis, we employed the novel Field Sweep Fourier Transform NMR to reconstrcut the 3.6 MHz wide linewidths. For more information see Rees, 2013.
Figure 1: The static solid state 195Pt NMR spectra of a 5 nm particle. The deconvolution shows the shifts of the various 'cores' of the platinum nanoparticle. The yellow central core represents bulk platinum metal and appears at a Knight shift of -35,350 ppm on the spectrum. Whilst the purple surface is mainly oxide (diamagnetic) and appears at the chemical shift of -20,000 ppm.
Solid Oxide Fuel Cells
We have used GIPAW DFT computational methods and 17O solid state NMR for the identification of interstitial oxide species responsible for conduction in rare earth apatite solid oxide fuel cell (SOFC) membrane materials. These methods are now being extended to oxide deficient transition metal perovskite materials used as SOFC electrodes, where disordered A site, B site and O vacancies are fundamental to their function. For more information see Rees, 2012.
Tight Hydrogen Bonds
I have worked on the development of 17O MAS NMR and its applications to various fields of materials, inorganic and organic chemistry. Our latest focus pertains to 17O MAS and DOR studies (coupled with further multinuclear MAS studies) in order to characterise and understand the hydrogen-bonding mechanism in alkali hemibenzoates. This research is closely integrated to GIPAW DFT computation in order to accurately constrain the proton position partaking in the H-bonded network. For more information see Rees, 2013.