Comparison of sizes, morphologies and optical properties of nio nanostructures synthesized using acetate and nitrate anions from nickel salts via hydrothermal method

Porous NiO nanocrystals were synthesized using a hydrothermal method in mediums of different anions from nickel salts, acetate (CH 3 COO - ) and nitrate (NO 3 -),followed by calcination at 500 °C. Firstly, β-Ni(OH) 2 powders with a hexagonal structure were formed. Using acetate and nitrate anions, the obtained β-Ni(OH) 2 powders were composed of thin nanosheets (0.8-2.1 μm in length), and a splinter-like structure self-assembled with longer nanosheets (9.8-24.2 μm), respectively. The difference in the interaction ability between the anions and the β-Ni(OH) 2 surfaces, affecting the growth behavior of the crystals, was examined using the density functional theory (DFT) method. After calcination, the β-Ni(OH) 2 turned into porous NiO with a cubic structure but their morphologies were unchanged. The porous NiO with longer nanosheets possessing higher crystallinity and larger surface area provided better UV-Vis absorption ability. © 2018, Chiang Mai University. All rights reserved

Photocatalytic activity of CuInS2 nanoparticles synthesized via a simple and rapid microwave heating process

In this research, visible–light photocatalytic activities of CuInS2 nanoparticles for degradation of three organic dyes (rhodamine B; RhB, methylene blue; MB, and methyl orange; MO) were investigated. The CuInS2 nanoparticles were synthesized by a simple and rapid microwave heating process using sodium sulfide as a sulfur source and then characterized by x–ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET), and UV–vis diffuse reflectance spectroscopy (UV–vis DRS) techniques. The synthesized CuInS2 nanoparticles exhibited excellent photocatalytic degradation activity to the cationic dyes (RhB and MB) when compared with that of anionic dye (MO). Zeta potential of the CuInS2 photocatalyst was measured to elucidate the adsorption ability toward dye molecules. A possible photocatalytic degradation mechanism was proposed based on active species quenching experiments and Mott–Schottky analysis

Microwave synthesis of ZnIn2S4/WS2 composites for photocatalytic hydrogen production and hexavalent chromium reduction

A rapid microwave synthesis route for the fabrication of ZnIn2S4 powder and ZnIn2S4/WS2 composites is presented. Firstly, the effects of different sulfur sources – thioacetamide and L-cysteine – on the physicochemical properties and photocatalytic H2 production of the synthesized ZnIn2S4 were investigated. It was found that well-defined flower-like ZnIn2S4 microspheres obtained from L-cysteine facilitated a relatively higher H2 production rate. Then, different loadings of WS2 were introduced into the well-defined flower-like ZnIn2S4 microspheres aiming to improve its photocatalytic H2 production. Compared to pure ZnIn2S4 and WS2, all ZnIn2S4/WS2 composite photocatalysts exhibited enhanced photocatalytic H2 production in the presence of Na2S/Na2SO3 as sacrificial reagents under UV-visible irradiation, where the ZnIn2S4/WS2-40% wt composite had the highest photocatalytic activity. For this material, 293.3 and 76.6 μmol h−1 g−1 of H2 gas were produced under UV-visible and visible light irradiation, respectively. In addition, the photoreduction activity of hexavalent chromium (Cr(VI)) by ZnIn2S4/WS2-40% wt was also investigated under visible light irradiation and it was observed that 98.5% of Cr(VI) was reduced within 90 min at pH 4

Enhanced visible-light-driven photocatalytic H2 production and Cr(vi) reduction of a ZnIn2S4/MoS2 heterojunction synthesized by the biomolecule-assisted microwave heating method

In this work, the biomolecule-assisted microwave heating synthesis of ZnIn2S4, along with the ZnIn2S4/MoS2 composites and their photocatalytic applications, were studied. Well-defined flower-like ZnIn2S4 microspheres synthesized at microwave heating time of 1 h provided the highest surface area and total pore volume, which offered the highest H2 production rate (111.6 μmol h−1 g−1). Different amounts of MoS2 were loaded into the ZnIn2S4 microspheres to form ZnIn2S4/MoS2 composites aiming to improve the H2 production rate. Among the fabricated ZnIn2S4/MoS2 composites, the ZnIn2S4/MoS2-40% wt composite exhibited the highest H2 production rate (200.1 μmol h−1 g−1) under UV-visible light irradiation. In addition, for the first time, this composite was applied for the photoreduction reaction of Cr(VI) ion under visible light irradiation. It provided higher photoreduction efficiency than the single components, where the efficiency was improved in the acidic solutions over the levels recorded in the basic solution. The charge transfer pathway and photocatalytic mechanisms of the ZnIn2S4/MoS2-40% wt photocatalyst have been proposed based on the results obtained from UV-visible diffuse reflectance spectroscopy, photoluminescence spectroscopy, electrochemical impedance spectroscopy, Mott–Schottky measurements and the silver photo-deposition experiment

Comparative Study of Silk Fibroin-Based Hydrogels and Their Potential as Material for 3-Dimensional (3D) Printing

Three-dimensional (3D) printing is regarded as a critical technology in material engineering for biomedical applications. From a previous report, silk fibroin (SF) has been used as a biomaterial for tissue engineering due to its biocompatibility, biodegradability, non-toxicity and robust mechanical properties which provide a potential as material for 3D-printing. In this study, SF-based hydrogels with different formulations and SF concentrations (1–3%wt) were prepared by natural gelation (SF/self-gelled), sodium tetradecyl sulfate-induced (SF/STS) and dimyristoyl glycerophosphorylglycerol-induced (SF/DMPG). From the results, 2%wt SF-based (2SF) hydrogels showed suitable properties for extrusion, such as storage modulus, shear-thinning behavior and degree of structure recovery. The 4-layer box structure of all 2SF-based hydrogel formulations could be printed without structural collapse. In addition, the mechanical stability of printed structures after three-step post-treatment was investigated. The printed structure of 2SF/STS and 2SF/DMPG hydrogels exhibited high stability with high degree of structure recovery as 70.4% and 53.7%, respectively, compared to 2SF/self-gelled construct as 38.9%. The 2SF/STS and 2SF/DMPG hydrogels showed a great potential to use as material for 3D-printing due to its rheological properties, printability and structure stability

Enhanced photocatalytic degradation of methylene blue by a direct Z-scheme Bi2S3/ZnIn2S4 photocatalyst

This study successfully synthesized Bi2S3/ZnIn2S4 composites with different weight percentages of Bi2S3 by cyclic microwave irradiation followed by wet impregnation. The photocatalytic activities of the Bi2S3/ZnIn2S4 composites were evaluated by the photodegradation of methylene blue in an aqueous solution. It was found that the 12.5%wt-Bi2S3/ZnIn2S4 photocatalyst exhibited the highest decolorization efficiency (95.4% within 300 min) with good stability against photocorrosion and good recyclability for photocatalytic reaction. Based on the results from UV–vis DRS, PL, photocurrent response measurement, and the active species trapping experiments, the enhanced photocatalytic activity of the Bi2S3/ZnIn2S4 photocatalyst was due to the increased ability to absorb visible light, and the enhanced charge separation and transportation between Bi2S3 and ZnIn2S4 through the Z-scheme mechanism. A direct Z-scheme charge transfer pathway for photocatalytic reaction over the Bi2S3/ZnIn2S4 photocatalyst was also proposed and discussed

Enhanced visible-light-driven photocatalytic H2 production and Cr(vi) reduction of a ZnIn2S4/MoS2 heterojunction synthesized by the biomolecule-assisted microwave heating method

In this work, the biomolecule-assisted microwave heating synthesis of ZnIn2S4, along with the ZnIn2S4/MoS2 composites and their photocatalytic applications, were studied. Well-defined flower-like ZnIn2S4 microspheres synthesized at microwave heating time of 1 h provided the highest surface area and total pore volume, which offered the highest H2 production rate (111.6 μmol h−1 g−1). Different amounts of MoS2 were loaded into the ZnIn2S4 microspheres to form ZnIn2S4/MoS2 composites aiming to improve the H2 production rate. Among the fabricated ZnIn2S4/MoS2 composites, the ZnIn2S4/MoS2-40% wt composite exhibited the highest H2 production rate (200.1 μmol h−1 g−1) under UV-visible light irradiation. In addition, for the first time, this composite was applied for the photoreduction reaction of Cr(VI) ion under visible light irradiation. It provided higher photoreduction efficiency than the single components, where the efficiency was improved in the acidic solutions over the levels recorded in the basic solution. The charge transfer pathway and photocatalytic mechanisms of the ZnIn2S4/MoS2-40% wt photocatalyst have been proposed based on the results obtained from UV-visible diffuse reflectance spectroscopy, photoluminescence spectroscopy, electrochemical impedance spectroscopy, Mott–Schottky measurements and the silver photo-deposition experiment