Phosphine- Arsine- and Chalcogenide-Based MOFs and Unusual Noble Metal Alloy Nanocatalysts

Friday, February 14, 2020


Dr. Simon Humphrey

Department of Chemistry

The University of Texas at Austin

Reception: Hand 1130 at 3:00 PM

Seminar: Hand 1144 at 3:30 PM

Abstract:

Recent advances in the synthesis, structures and unique post-synthetic modifications of
MOFs based on triarylphosphine (R3P), triarylarsine (R3As) and the corresponding
chalcogenides (R3P=E or R3As=E; E = O, S, Se) will be presented. The use of ligands
containing heavier p-block elements as MOF building blocks allows the introduction of ‘soft’
lone pairs that are energetically well-suited for post-synthetic modifications with low-valent
metal species of interest in catalysts. In addition, the variable oxidation states available to
the heavier group 15 and 16 elements (EIII/EV or EII/EIV/EVI, respectively) permit a range of
other, more unusual post-synthetic modifications, which provide routes toward reactive
organic ligands and moieties that cannot be obtained or stabilized in molecular complexes.
Microwave-assisted heating in the polyol synthesis of noble metal nanostructures provides
access to randomly alloyed structures of binary and ternary phases that cannot be obtained
using conventional heating methods. The resulting nanostructures are solid-solution
structures that are metastable and resist segregation upon heating above 300 °C. Model
heterogeneous catalysis studies reveal order-or-magnitude increases in hydrogenation
reactivity, based on synergistic (ensemble and electronic) effects. High-resolution electron
microscopy, EXAFS and PDF coupled with experiment and theory allow a deeper understanding of reactivity benefits due to nanoscale alloying. Fine control over alloy composition allows for optimization of reactivity for targeted applications, including in electrochemistry and in catalytic nitrate reduction and sulfide fouling resistance in water treatment.

Bio:

Dr. Simon Humphrey was born in Wisbech, England in 1979. As an undergraduate he attended The University of East Anglia, Norwich (1998−2002) and The University of California at Santa Barbara (2000−2001) and obtained a Master of Chemistry degree (MChem, Class I). He then moved to The University of Cambridge (2002−2005) as a graduate student at St John’s College and obtained his Ph.D. studies under the supervision of Paul T. Wood, in the field of magnetic and porous coordination polymer synthesis. He then worked under the co-supervision of T. Don Tilley and Gabor A. Somorjai as a US Department of Energy Postdoctoral Research Associate at the Lawrence Berkeley National Laboratory (2005−2007), in the field of nanoparticle catalysis. In 2006, he undertook a Fellowship at St John’s College, Cambridge, before joining the Faculty at the University of Texas at Austin as an Assistant Professor in 2009.


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