Brown University School of Engineering

Christopher Wright - "Catalyst structure and annealing dynamics from the pair distribution function: a basis for rational catalyst design"

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Tuesday, May 06, 2014 12:00pm - 1:00pm

Greetings! You are invited to the upcoming Center for the Capture and Conversion of CO2 presentation on Tuesday, May 6th (12:00 to 1:00 pm in Barus and Holley 190). The speaker is: Christopher Wright - "Catalyst structure and annealing dynamics from the pair distribution function: a basis for rational catalyst design" Abstract: An important prerequisite for heterogeneous and homogeneous catalyst rational design is an atomistic understanding of catalyst structure. In this work we use x-ray total scattering and atomic pair distribution function (PDF) analysis to elucidate the atomic structures of nanoparticles (NPs) and homogeneous metal complexes. We explore the annealing induced structural change in Ni30Pd70 nanoparticles, the disorder in 2nm Ag and 2nm Au NPs, and introduce a proof of concept experiment into using PDF to understand the structure of a homogeneous catalyst model system. Our NiPd results show that oxidative and reductive annealing have different effects on the catalyst structure. The formation of different surface species may induce changes in electrocatalytic activity for the formic acid oxidation reaction. The 2nm Ag and Au NP studies show the polycrystallinity of the 2nm Au NPs and the polydispersity of the Ag NPs. Both NPs show local disorder in their PDF possibly contributing to their catalytic activity. Finally the homogeneous model system, Fe2Cp2(CO)4 dissolved in heptane, shows the possibility for x-ray based PDF to determine the structure of organometallic molecules in reaction like environments. The implications for future catalyst design will also be discussed.