Intermetallic surfaces are ideally suited for fundamental catalysis science, where understanding electronic and geometrical effects induced by the promoting element on overall performance has been the goal of many studies. Moreover, systematic variation of the intermetallic composition provides a practical means to optimize selectivity and yield for the desired process. This talk will present the successful implementation of this strategy to parahydrogen enhanced NMR, where the conversion of parahydrogen singlet spin order into NMR-observable Zeeman order can amplify NMR signal intensities by four orders of magnitude or more. The goal is to remove the magnetic equivalence of the protons in parahydrogen and introduce additional couplings to target nuclear spins of a substrate molecule while retaining the spin correlation inherent to the parahydrogen singlet state. Several successful examples of parahydrogen enhanced NMR in liquids and gases using intermetallic nanoparticle catalysts prepared by a variety of novel synthetic strategies will be discussed. An unexpected result of this work is that the parahydrogen enhanced NMR signals are found to be exquisitely sensitive to the catalyst surface composition. In addition, the increased pairwise selectivity, by more than three orders of magnitude compared to their monometallic counterparts in some cases, has promising applications to sensitivity enhanced NMR spectroscopy and biomedical imaging with all the well-established advantages of heterogeneous catalysis.

Hyperpolarization from parahydrogen catalyzed by intermetallic nanoparticles

ACS Spring Meeting 2021

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