EFRC seminar 11/14/13

14 Nov 2013

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


Mario A. Alpuche Avilés

Department of Chemistry, University of Nevada, Reno



We propose the development of electrochemical methods to study semiconductors in colloidal suspension. The first part of this talk will introduce 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 (Figure 1). 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 will introduce 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.

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