Milica Košević

Titanium coated with high-performance nanocrystalline ruthenium oxide synthesized by the microwave-assisted sol-gel procedure

Ruthenium oxide coating on titanium was prepared by the sol–gel procedure from well-defined colloidal oxide dispersions synthesized by the microwave (MW)-assisted hydrothermal route under defined temperature and pressure heating conditions. The dispersions were characterized by dynamic light scattering (DLS) measurements and scanning electron microscopy (SEM). The electrochemical properties were analyzed as capacitive performances gained by cyclic voltammetry and electrochemical impedance spectroscopy and as the electrocatalytic activity for oxygen evolution from acid solution. The obtained dispersions were polydisperse and contained regular particles and agglomerates of increasing surface energy and decreasing particle size as the MW-assisted heating conditions were intensified. Owing to these features of the precursor dispersions, the obtained coatings had considerably improved capacitive performances and good electrocatalytic activity for oxygen evolution at high overpotentials.

Supercapacitors based on graphene/pseudocapacitive materials

In this work composites of graphene and SnO 2 were successfully prepared by single step simultaneous synthesis of SnO 2 and reduction of graphene oxide (GO). Three different compositions of precursor solution resulted with different composite materials containing graphene and SnO 2 . The reaction was carried out by using microwave-assisted hydrothermal synthesis. Scanning electron microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDX) gave insight into morphology and composition of the obtained materials. Good capacitive/pseudocapacitive properties of the obtained material suitable for supercapacitor application were registered by using cyclic voltammetry from where specific capacitance values up to 93 F g -1 were determined.

Impedance characteristics of aluminum with sol-gel ceria protective coating during the exposure to chloride corrosion agent

Electrochemical impedance characteristics of bare Al and Al with CeO2 coating prepared sol-gel procedure from the ceria sol are investigated. The corrosion behavior is monitored during the exposure to 3 wt. % NaCl aqueous solution. Experimental data are fitted to various equivalent electrical circuits with special attention to inductive features. Equivalent electrical circuits involving inductivity represent impedance response equally well as the ones without inductivity, although the parameter values gained from the former correspond better to the proposed model of physicochemical changes during corrosion of investigated samples.