428023 Probing the Mechanism of Optically Induced, Charge-Carrier Driven Chemical Transformations on Plasmonic Metal Nanoparticle Surfaces

Wednesday, November 11, 2015
Exhibit Hall 1 (Salt Palace Convention Center)
Calvin Boerigter, Robert Campana, Matthew Morabito and Suljo Linic, Department of Chemical Engineering, University of Michigan, Ann Arbor, MI

Title: "Probing the mechanism of optically induced, charge-carrier driven chemical transformations on plasmonic metal nanoparticle surfaces"

An emerging field of heterogeneous catalysis involves the use of plasmonic metal nanoparticles as photocatalysts. These systems take advantage of the excitation of localized surface plasmon resonance (LSPR) in the presence of solar spectrum light to enhance rates of catalytic reactions on plasmonic metal nanoparticles. It has been proposed that these chemical transformations take place through an electron transfer from the plasmonic catalyst to the adsorbate, leading to an electron-driven activation of chemical transformations. While the general features of the process are reasonably well understood, there are certain aspects of the mechanism that are less clear. Until recently, the nature of the interaction between the localized surface plasmon states and adsorbate electronic states (i.e. the nature and pathway of charge transfer within the catalyst system) had not been thoroughly studied.

In the presented studies, probe molecules were used along with silver nanoparticle catalysts in a number of Raman spectroscopy experiments to provide further insights into the electron-driven mechanism of photo-chemical reactions on the surface of plasmonic metal nanoparticles. These experimental studies were combined with FDTD modeling of the system’s optical properties and DFT modeling of localized electronic structures to obtain a complete picture of the fundamental charge transfer processes in these photocatalytic systems. Herein, we will shed light on the nature of the interaction between localized surface plasmon states and the excited electronic states of the adsorbate and demonstrate how these interactions can lead to chemical transformations. We will discuss the implications of our studies on the chemical activity and selectivity of plasmon-mediated photo-chemical transformations on metal nanoparticles.

Boerigter, C., Campana, R., Morabito, M. & Linic, S. Probing the mechanism of optically induced, charge-carrier driven chemical transformations on plasmonic metal nanoparticle surfaces. In preparation, (2015).

Marimuthu, A., Zhang, J. & Linic, S. Tuning selectivity in propylene epoxidation by plasmon mediated photo-switching of Cu oxidation state. Science 339, 1590–3 (2013).

Christopher, P., Xin, H., Marimuthu, A. & Linic, S. Singular characteristics and unique chemical bond activation mechanisms of photocatalytic reactions on plasmonic nanostructures. Nat. Mater. 11, 1044–50 (2012).

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