Photocatalytic Properties of Eco-Friendly ZnO Nanostructures on 3D-Printed Polylactic Acid Scaffolds

The present paper reports a novel approach for fabrication of eco-friendly ZnO nanoparticles onto three-dimensional (3D)-printed polylactic acid (PLA) scaffolds/structures. Several alcohol-based traditional Greek liquors were used to achieve the corrosion of metallic zinc collected from a typical galvanic anode to obtain photocatalytic active nanostructured ZnO, varying from water, to Greek “ouzo” and “raki”, and pure ethanol, in combination with “Baker’s ammonia” (ammonium bicarbonate), sold worldwide in every food store. The photocatalytic active ZnO nanostructures onto three-dimensional (3D)-printed PLA scaffolds were used to achieve the degradation of 50 ppm paracetamol in water, under UV irradiation. This study provides evidence that following the proposed low-cost, eco-friendly routes for the fabrication of large-scale photocatalysts, an almost 95% degradation of 50 ppm paracetamol in water can be achieved, making the obtained 3D ZnO/PLA structures excellent candidates for real life environmental applications. This is the first literature research report on a successful attempt of using this approach for the engineering of low-cost photocatalytic active elements for pharmaceutical contaminants in waters

The mechanical and physical properties of 3D-Printed materials composed of ABS-ZnO nanocomposites and ABS-ZnO microcomposites

In order to expand the mechanical and physical capabilities of 3D-printed structures fabricated via commercially available 3D printers, nanocomposite and microcomposite filaments were produced via melt extrusion, 3D-printed and evaluated. The scope of this work is to fabricate physically and mechanically improved nanocomposites or microcomposites for direct commercial or industrial implementation while enriching the existing literature with the methodology applied. Zinc Oxide nanoparticles (ZnO nano) and Zinc Oxide micro-sized particles (ZnO micro) were dispersed, in various concentrations, in Acrylonitrile Butadiene Styrene (ABS) matrices and printable filament of ~1.75 mm was extruded. The composite filaments were employed in a commercial 3D printer for tensile and flexion specimens' production, according to international standards. Results showed a 14% increase in the tensile strength at 5% wt. concentration in both nanocomposite and microcomposite materials, when compared to pure ABS specimens. Furthermore, a 15.3% increase in the flexural strength was found in 0.5% wt. for ABS/ZnO nano, while an increase of 17% was found on 5% wt. ABS/ZnO micro. Comparing the two composites, it was found that the ABS/ZnO microcomposite structures had higher overall mechanical strength over ABS/ZnO nanostructures. © 2020 by the authors. Licensee MDPI, Basel, Switzerland

Highly sensitive layered ZnO/LiNbO3 SAW device with InOx selective layer for NO2 and H2 gas sensing

Layered surface acoustic wave (SAW) devices for the monitoring of NO2 and H-2 in synthetic air have been fabricated on XZ LiNbO3 with a 1.2 mu m ZnO guiding layer. To increase selectivity and sensitivity, InOx layers of thickness 40 and 200nm were employed. The sensor's performance was analyzed in terms of frequency shift as a function of different gas concentrations. The sensors were tested over a range of operating temperatures between 100 and 273 degrees C. A large response magnitude with fast response and recovery time was observed. Positive frequency shifts of 91 kHz for 2.125 ppm of NO, and negative frequency shifts of 319 kHz for 1% of H-2 in synthetic air are presented; demonstrating the high sensitivity of the layered SAW structure with the DC sputtered InOx thin film. The surface of the layered SAW structure was studied by atomic force microscopy (AFM) before and after the deposition of the InOx selective layer. The AFM analysis demonstrates that the NO films deposited on ZnO, the guiding layer, resulted in an increase in surface area due to the highly uniform nanostructured surface morphology of InOx