We present our recent results of the photoelectrochemistry of single elements obtained by our group and discuss our current interpretation of these results in terms of the detection of single nanoparticles to higher order aggregates. The focus of our presentation is to address the measurements and limitations of single anatase nanoparticle photoelectrochemistry and other semiconducting materials: e.g., dye-sensitized TiO2. In our measurements, we detect discrete photoelectrochemical events of suspended materials in MeOH as they collide with our working electrode. The observed current transient yields the nature of the electrode-NP interaction. Our detection setup measures the free electrons available at the conduction band of TiO2 while the valence band holes oxidize MeOH. We have been able to measure the photooxidation products quantitatively, and we relate the results of the product formation from suspended nanoparticles to the results obtained for single entities immobilized on an electrode surface. The nature of the working electrode determines the material type of interaction with nanoparticles sticking to Pt while a different behavior is observed F-doped SnO2 (FTO) microelectrodes. We present the method to prepare ultramicroelectrodes from materials that are not available as thin wires and demonstrate the use of these electrodes in the collision experiments. The colloidal behavior of the material in suspension also influences the electrochemical response, and we discuss the relationship between the formation of aggregates and the stochastic photoelectrochemical response. Single nanoparticles behavior is obtained under very specialized conditions of concentration, illumination power, and other electrochemical experimental conditions. Under these specific conditions, we propose that the results correspond to single nanoparticle photoelectrochemistry with low recombination losses.

Photoelectrochemical detection of semiconductor nanoparticles: Electrochemical characterization of single nanoparticles and their colloidal behavior

256th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.