Characterization of Different Types of Screen-Printed Carbon Electrodes Modified Electrochemically by Ceria Coatings

Electrochemical formation of ceria (mixed Ce2O3 and CeO2) coatings on different types of screen-printed carbon electrodes (SPCEs) (based on graphite (C110), carbon nanotubes (CNT), single-walled carbon nanotubes (SWCNT), carbon nanofibers (CNF), and mesoporous carbon (MC)) were studied. Their potential applications as catalysts for various redox reactions and electrochemical sensors were investigated. The ceria oxide layers were electrodeposited on SPCEs at various current densities and deposition time. The morphology, structure, and chemical composition in the bulk of the ceria layers were studied by SEM and EDS methods. XRD was used to identify the formed phases. The concentration, chemical composition and chemical state of the elements on the surface of studied samples were characterized by XPS. It was established that the increase of the concentration of CeCl3 in the solution and the cathode current density strongly affected the surface structure and concentration (relation between Ce3+ and Ce4+, respectively) in the formed ceria layers. At low concentration of CeCl3 (0.1M) and low values of cathode current density (0.5 mA·cm−2), porous samples were obtained, while with their increase, the ceria coatings grew denser.