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Titanium dioxide (TiO2) can only be stimulated by UV light, making its real application for photocatalytic water treatments ineffective, particularly under sunlight and visible light irradiation. As a result, significant efforts have been conducted over the last decades to fabricate visible light-active TiO2 photocatalysts through band-gap engineering. Herein, nitrogen-doped titanium dioxide (N-TiO2) photocatalysts were effectively prepared by utilizing a simple sol–gel process with ethanol as a single solvent and urea as the nitrogen source under ambient temperature and pressure. The effects of urea concentration (0, 2, 4, 6 urea/TTIP mol ratio) on the optical, structural, morphological, and photocatalytic properties of the photocatalysts were investigated. SEM morphology revealed an aggregated nano-spherical shape in all samples. HR-TEM and SAED patterns showed an anatase phase of 2-N-TiO2. The X-ray diffraction analysis also showed a pure anatase phase for pure TiO2, 2-N-TiO2, and 4-N-TiO2. However, the crystalline phase transformed to amorphous for 6-N-TiO2. The crystallite size reduced from 14.16 to 9.76 nm upon increasing urea concentration. The band-gap energy of N-TiO2 also decreased from 3.25 to 2.95 eV. Furthermore, the photocatalytic experiment was examined for the degradation of colorless and colored pollutants, such as salicylic acid (SA), methyl blue (MB), and rhodamine B (RhB). The results showed the photocatalytic activity of 2-N-TiO2 exhibited an optimum efficiency compared to the 4-N-TiO2 and 6-N-TiO2, for photocatalytic degradation of SA (k = 0.0265 min−1), MB (k = 0.0180 min−1) and RhB (k = 0.1071 min−1), under visible light irradiation. Therefore, the results suggest that crystallite size, urea (as an N dopant) concentration, and organic model pollutants were critical parameters for the photocatalytic activity of N-TiO2 under visible irradiation. [ABSTRACT FROM AUTHOR]

In this study, ceramic materials of Mg(Ti0.99Sn0.01)O3 were synthesized and decorated on reduced graphene oxide, forming a nanocomposite of rGO/Mg(Ti0.99Sn0.01)O3 (rGO/MTS001). The successful synthesis results were confirmed by XRD, UV–vis analysis, FT-IR, and SEM-EDS. The MTS001 has a flower-like morphology from scanning electron microscopy (SEM) analysis, and the nanocomposites of rGO/MTS001 showed MTS001 particles decorated on the rGO's surface. The electrochemical performance of rGO/MTS001 and MTS001 was investigated by determining the specific capacitance obtained in 1 M H2SO4 solution by cyclic voltammetry, followed by galvanostatic charge–discharge analysis using a three-electrode setup. The rGO/MTS001 achieved a specific capacitance of 361.97 F g‒1, compared to MTS001 (194.90 F g‒1). The capacitance retention of rGO/MTS001 nanocomposite also depicted excellent cyclic stability of 95.72% after 5000 cycles at a current density of 0.1 A g‒1. The result showed that the nanocomposite of ceramics with graphene materials has a potential for high-performance supercapacitor electrodes. [ABSTRACT FROM AUTHOR]

Studies on the deposition of ZnO nanosheets grown vertically and perpendicular to conductive substrates have been conducted to obtain tall-type nanosheets (approximately 15 µm in height). However, some applications require shorttype nanosheets with a height of about 1µm or less. In this study, short-type ZnO nanosheets were electrodeposited on indium-doped tin oxide substrates under galvanostatic (constant current) mode for a short deposition time. Then, the key parameters to form nanosheet layers with a height in the micrometer order and with good coverage were evaluated. Deposition was performed at 1 mA/cm² for 60 s. Ar gas was initially bubbled into the electrolyte solution during electrodeposition to remove oxygen. Then, the solution was compared with solutions that did not undergo bubbling. Various electrolyte compositions (various concentrations of acetate and nitrate) were observed in solutions under the non-Ar bubbling condition. Moreover, the oxygen in the solution remarkably affected the morphology of the nanosheet, which became much denser and taller. Therefore, altering electrolyte composition affects morphology, although the effect is not as significant. Electrolyte composition must be optimized to produce the desired short and dense nanosheets because a low concentration of each anion leads to the production of a non-nanosheet layer, whereas a high concentration causes reduction in the density coverage of the nanosheet. A complete discussion of this phenomenon is presented in this study. [ABSTRACT FROM AUTHOR]

Spinel-based hydroxyapatite composite (SHC) has been synthesized utilizing bovine bones as the source of the hydroxyapatite (HAp) and beverage cans as the aluminum (Al) source. The bovine bones were defatted and calcined in the air atmosphere to transform them into hydroxyapatite. The beverage cans were cut and milled to obtain fine Al powder and then sieved to obtain three different particle mesh size fractions: +100#, −140# + 170#, and −170#, or Al particle size of >150, 90–150, and <90 µm, respectively. The SHC was synthesized using the self-propagating intermediate-temperature synthesis (SIS) method at 900 °C for 2 h with (HAp:Al:Mg) ratio of (87:10:3 wt.%) and various compaction pressure of 100, 171, and 200 MPa. It was found that the mechanical properties of the SHC are influenced by the Al particle size and the compaction pressure. Smaller particle size produces the tendency of increasing the hardness and reducing the porosity of the composite. Meanwhile, increasing compaction pressure produces a reduction of the SHC porosity. The increase in the hardness is also observed by increasing the compaction pressure except for the smallest Al particle size (<90 µm), where the hardness instead becomes smaller. [ABSTRACT FROM AUTHOR]

In this study, we report the synthesis of ZnO nanoparticles from Zn dross via hydrometallurgical method by using acetic acid as a leaching agent. D205 dye molecules were then adsorbed onto Zn dross originated ZnO nanoparticle film. The optical absorption confirms the photosensitization of the synthesized ZnO nanoparticles with dye. The photoluminescence spectra reveal the excitonic- and defect-related emission of ZnO nanoparticles. Compared to ZnO nanoparticles only, the longer emission lifetime of ZnO nanoparticles with adsorbed dye indicates the transfer of photoexcited electrons from dye to the ZnO nanoparticles. Furthermore, photodetection characterization of ZnO film show the enhanced current density with the presence of dye under simulated solar illumination, while that measured at dark is similar in both films with and without dye. This result confirms the potentiality of Zn dross to be recycled into valuable ZnO nanoparticles particularly for the applications in the visible light region, especially for sensing. [ABSTRACT FROM AUTHOR]