High Throughput Spectroscopic Catalyst Screening via Surface Plasmon Spectroscopy
Final rept. 26 Jun 2014-25 Mar 2015
MELBOURNE UNIV PARKVILLE (AUSTRALIA)
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Over the last decade, shape controlled synthesis of nanoparticles NPs has opened up the possibility to study heterogeneous catalysis on a variety of well-defined nanoscale crystal facets. This investigation examined using single particle surface plasmon spectroscopy SPS as a tool for real-time monitoring of catalytic processes and chemical intermediates during surface redox reactions e.g., hydrogen spillover. The ultimate goal of this research is to be able to identify which crystal facets determine overall catalytic nanoparticle efficiency in heterogeneous reactions. Dark field spectroscopy was used to monitor hydrogen dissociation on single gold nanoparticles embedded in metal oxide supports. Individual gold nanorods were monitored in realtime to reveal peak position, full width at half maximum and relative intensity of the surface plasmon resonances during repeated N2-H2-N2 and air-H2-air cycles. It was found that hydrogen does not dissociate on gold nanorods at room temperature when in contact with silica and that electrons or hydrogen atoms migrate from Pt nanoparticles to Au nanoparticles through the supporting metal oxide at room temperature. The results show that hydrogen spillover, surface dissociation of reactants and surface migration of chemical intermediates can be detected and monitored in real time at the single particle level. The ultimate sensitivity of the SPS technique was determined using chemically synthesized gold nanorods as individual optical elements in a quasi-solid-state ion-gel capacitor. The smallest detectable changes occurred from 10mV applied voltages, which yielded less than 100 electrons per nanorod. An increase in electron density was found to lead to an overall increase in scattering intensity and was described for the first time using Drude model derivations. The approach involved building large nanoparticle combinatorial libraries for high throughput screening.
- Physical Chemistry