Characterizing Substrate-Surface Interactions on Alumina-Supported Metal Catalysts by Dynamic Nuclear Polarization-Enhanced Double-Resonance NMR Spectroscopy.
Frédéric A PerrasJ Daniel PadmosRobert L JohnsonLin-Lin WangThomas J SchwartzTakeshi KobayashiJ Hugh HortonJames A DumesicBrent H ShanksDuane D JohnsonMarek PruskiPublished in: Journal of the American Chemical Society (2017)
The characterization of nanometer-scale interactions between carbon-containing substrates and alumina surfaces is of paramount importance to industrial and academic catalysis applications, but it is also very challenging. Here, we demonstrate that dynamic nuclear polarization surface-enhanced NMR spectroscopy (DNP SENS) allows the unambiguous description of the coordination geometries and conformations of the substrates at the alumina surface through high-resolution measurements of 13C-27Al distances. We apply this new technique to elucidate the molecular-level geometry of 13C-enriched methionine and natural abundance poly(vinyl alcohol) adsorbed on γ-Al2O3-supported Pd catalysts, and we support these results with element-specific X-ray absorption near-edge measurements. This work clearly demonstrates a surprising bimodal coordination of methionine at the Pd-Al2O3 interface.
Keyphrases
- high resolution
- highly efficient
- amino acid
- heavy metals
- wastewater treatment
- mass spectrometry
- escherichia coli
- magnetic resonance imaging
- computed tomography
- cystic fibrosis
- biofilm formation
- single molecule
- transition metal
- microbial community
- metal organic framework
- pseudomonas aeruginosa
- candida albicans
- medical students