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Thursday, August 28, 2014

Electrochemistry of Semiconductor Nanoparticles: Single Nanoparticle Detection and Size Dependent Thermodynamic Properties

Analytical Analytical Seminar
1640 Chemistry
4:00 PM - 5:30 PM

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Speaker:   Mario Alpuche, University of Nevada, Reno
Abstract:   Our group develops electrochemical methods to study semiconductors in colloidal suspension. The first part of this talk introduces an electrochemical technique to study photocatalytic processes of colloidal semiconducting nanoparticles. We have demonstrated the detection of individual anatase nanoparticles interacting with an electrode by photoelectrochemical currents. These interactions carry information about the photochemical process at the single nanoparticle level and this seminar will present our advances towards measuring the particle by particle kinetics of electron transfer reactions for the photooxidation of methanol, proposed as a model system. The second part of the seminar covers our studies of size-dependent thermodynamic properties of ZnO nanoparticles. Experiments with colloidal ZnO are used to demonstrate that electrochemical studies can contribute to understand the different aspects that drive nucleation and growth during NP synthesis. The surface energy of ZnO nanoparticles is one of such thermodynamic properties that we can be determined from the size-dependence of the electrochemical potential of the reduction of ZnO. We present our measurements of surface tension of the solid-liquid interface of ZnO nanoparticles in MeCN; in turn, the surface tension value has been used to estimate the surface free energy of nanoparticles in the range of 20 to 80 nm.