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Speaker: Zhu Zhang MSc 

Title: Monitoring local ion concentration variations by iontronic microscopy

Abstract: The ions concentration at a charged solid-liquid interface is dictated by the Electric Double Charging (EDL) formation, chemical reactions, charge transfer, and ionic absorption. It is a challenging task to measure the local ion concentration with high spatial and temporal resolutions. Here we present experimental measurements of the potentiodynamic optical contrast from the scattering signal of nano-objects at various electrochemical potentials. This method allows us to make a direct correlation between the ion concentration around the surface of nano-objects and the observed optical modulation signal. Achieving a simultaneously high temporal and high spatial resolution is essential for filtering out the electrochemical noise caused by surface heterogeneity in conventional amperometry measurements. The potentiodynamic optical contrast from nano-objects correlated with electrochemical reactions, paving the ground for expanding iontronic microscopy to nanoscale electroscopy. Furthermore, this dynamic and correlative measurement allows us to separate the contribution of surface ion absorption to the potentiodynamic scattering signal from that of the diffuse EDL, which in turn can provide new insights into the dynamics of complex electrochemical processes at the solid-liquid interface. In this talk, I will show you some results including: potentiodynamic optical contrast during Electric Double Layer(EDL) charging/discharging process and electrochemical reactions inside of the nanoholes.

[1] K. Namink, X. Meng, M. T. M. Koper, P. Kukura, S. Faez, Phys. Rev. Applied 13, 044065, 2020

[2] Z. Zhang, J. Yang, C. Lian, S. Faez , J. Phys. D: Appl. Phys. 54, 384005, 2021

[3] Z. Zhang, I.B. Dogru Yüksel, A. Peters, S. Faez,