Material characterisation - always a complex task
The range of application of materials strongly depends on their respective electrical properties. Electrochemical methods allow the investigation of basic materials such as metals (steel, copper), but also semiconductors (silicon, TiO2), and insulators (polymers). Since these materials show extremely diverse electrical and electrochemical behavior, measurement methods and measurement setups must be developed and implemented accordingly to determine thermodynamic and kinetic information such as electrical bulk properties, redox potentials, overpotentials and selective oxidation or corrosion behavior. Commonly used methods include cyclic voltammetry and impedance spectroscopy in extended measurement setups for the control of experimental conditions combined with complementary analytical techniques (SEM, Raman, XRD and XPS).
Examples within our field of research are:
- The electrochemical investigation of high-temperature processes in different gas atmospheres, such as high-temperature corrosion of steel or thermal oxidation of copper. High-temperature cyclic voltammetry (HT-CV) is a rarely used electrochemical technique with high surface sensitivity operating at temperatures above 400 °C.
- For the evaluation of the hydrogen permeation behavior through metals, a special cell setup is used, which includes a double electrochemical cell separated by the metallic membrane to undergo investigation. The registered current characterizes the ability of the metal to absorb and transport hydrogen atoms through the membrane.
- Some semiconductors exhibit photoelectrocatalytic activity when illuminated with light of sufficient energy. In wastewater treatment, TiO2 and WO3 are used as photocatalysts for the oxidation of organic contaminants. In photoelectrochemical processes, charge carriers are generated which lead to oxidation or reduction processes, as in photoassisted etching or deposition processes.