T. Frade

Studies on the Stability of Zn and Zn – TiO2 Nanocomposite Coatings Prepared by Pulse Reverse Current

Zn―TiO 2 nanocomposite thin films were obtained from the occlusion electrodeposition method using pulsed reverse current electrolysis, from acidic zinc sulfate solutions, on a Ti support. According to the glow discharge optical emission spectrometry analysis, the TiO 2 nanoparticles are incorporated and uniformly distributed through out the metallic matrix. The 24 h stability of these coatings, in neutral sulfate solutions, has been investigated and compared with the behaviorof the Zn electrodeposits. The stability of the films is strongly dependent on their morphologic and structural characteristics, namely the crystallite size and texture of the matrix. It has been found that a protective layer, mainly composed by Zn 4 SO 4 (OH) 6 and ZnS0 4 , is easily formed on the Zn―TiO 2 films than on the Zn electrodeposits. Such protective layer acts as a barrier against further metal dissolution, proved by the solution analysis using atomic absorption spectrophotometry and anodic stripping voltammetry of the solution.

Fotoeletrodegradação do corante AO7 utilizando filmes de nanocompósitos de ZnO-TiO2

The Zn-TiO2nanocomposite films were prepared by electrodeposition, using an acidic zinc sulphate solution with TiO2 nanoparticles in suspension. The as-deposited samples have been heated in air at 450 oC for 6 h. The XRD and SEM analyses pointed out to the metal matrix conversion from Zn to ZnO and a rich morphology of needles-shaped grains. These materials were used on the photoelectrochemical degradation of AO7, which was efficiently degraded, with 40% of color removal, after 2 h period at 1.0 V, under white light irradiation. The apparent first order rate constant of the photoelectrodegradation reaction was 4.12 x 10-3 min-1.

ZnO Nanostructured Thin Films Applied on Ibuprofen Photoelectrodegradation

ZnO nanorods were prepared on fluorine doped tin oxide (FTO) using the electrodeposition method. The architecture of the ZnO nanorods was strongly modified by changing the applied potential and bath composition. Scanning electron microscopy (SEM) confirmed the successful formation of ZnO nanorods and the diameter increasing due to the increase of deposition potential and nitrate zinc concentration. The annealed ZnO electrodes demonstrated a good performance on the Ibuprofen degradation. Percentage values of Ibu degradation varying between 22 and 30 % for 3 h period were obtained.

Morphological Characterization of Electrodeposited Zinc-based Matrix Composites

Research at the nanometer scale, aiming to create novel materials and devices offering better performance than those of macro/micro systems, is currently of great relevance in many topics of modern science, technology and engineering. In what concerns coatings technology, the nanocomposite films can offer excellent properties in different applications, representing their morphological characterization a great challenge.