Papers by Author: Wen Ku Chang

Abstract: This study used a photo-reduction method to investigate cuprous oxide (Cu2O) self-assembled micro/nanostructures, and design a test specimen with an electron concentration gradient distribution. It also observed the Cu2O reduction of the self-assembled structure with respect to electron density. SEM analysis was adopted to analyze the growth mechanism and growth model. The results showed that, its structure size increased with photo-reduction time, and as the reduction solution concentration increased, its structure crystallinity declined. The basic unit of a self-assembled microstructure was Cu2O at a diameter of 10~15nm, then these particles conglomerate in self-assembly to form various kinds of Cu2O micro/nanostructures with respect to reduction electron density, and primarily presented in the form of a cone or cube. In the process of continuous self-assembly, there were many micro-defects under the perfect crystal surface. Considering the growth rate, the final growth surface of the structure was (111) or (100).

Abstract: Zinc stannate Zn2SnO4 (ZTO) nanoparticles were synthesized via a hydrothermal process utilizing sodium carbonate (Na2CO3) as a weak basic mineralizer. The samples were hydrothermally treated at 150, 200, and 250oC for 48 h. The X-ray diffraction (XRD) patterns show that the highly-crystalline ZTO nanostructure could be formed in a well-dispersed manner for the 250°C sample at a particle size of less than 50 nm. As determined from transmission electron microscopy (TEM) results, ZTO nanoparticles are face-centered cubic single crystals agglomerated together. The Raman spectra results showed that the ZTO nanocrystals have a spinel structure. Furthermore, photocatalytic activity was tested with methylene blue (MB) by UV irradiation. The ZTO synthesized by the 2 M Na2CO3 mineralizer at 250oC demonstrated excellent photocatalytic activity. The ZTO treated three different ways had three distinct UV-Visible absorption curves, which directly influences their corresponding photocatalytic activity.