77. Quartz Crystal Microbalances for On-line Monitoring of Nanostructures Growth

Quartz Crystal Microbalances (QCM) are widely used for monitoring materials growth in vacuum physical deposition techniques; as a more complex application, QCMs are also used for on-line monitoring of thin films deposition in liquid thanks to electrochemical reactions onto quartz electrode (EQCM). Our goal here is to demonstrate that QCMs can also be used for on-line monitoring of hydrothermal nanostructures growth as well as for obtaining information on the synthesis reaction kinetic. In practice, first, we model the QCM in solution by means of a lumped element circuit; afterwards, rather than only the resonant frequency, we measure the entire QCM admittance spectrum around the resonant frequency, thus obtaining more information. As an example, we show that this approach allows to clearly distinguish the growth of different types of ZnO nanostructures, namely nanorods and nanoplatelets, on the QCM surface and the reaction dynamics.