Solvothermal synthesis of CdS nanowires templated by polyethylene glycol

CdS nanowires were solvothermally synthesized from Cd(NO₃)₂ and S powder using ethylenediamine as a solvent and polyethylene glycol (PEG) as a template. Hexagonal CdS with P6₃mc space group was detected using XRD and SAED, results which are in good accordance with those obtained by the simulation. SEM, TEM and HRTEM revealed the gradual development of nanowires in the [0 0 1] direction with a number of atoms aligning in a crystal lattice. Raman spectra of different products showed the fundamental and overtone modes at the same wavenumbers of 300 and 601 cm⁻¹, respectively. Their relative intensities at different molecular weight PEG were influenced by the anisotropic geometry of the products. Their photoluminescence peaks were detected at the same wavelengths of 518 nm. A formation mechanism for CdS nanowires was also proposed to relate to the experimental results.     

Formation of LiNi0.5Co0.5VO4 nano-crystals by solvothermal reaction

LiNi_0.5Co_0.5VO₄ nano-crystals were solvothermally prepared using a mixture of LiOH·H₂O, Ni(NO₃)₂·6H₂O, Co(NO₃)₂·6H₂O and NH₄VO₃ in isopropanol at 150–200 °C followed by 300–600 °C calcination to form powders. TGA curves of the solvothermal products show weight losses due to evaporation and decomposition processes. The purified products seem to form at 500 °C and above. The products analyzed by XRD, selected area electron diffraction (SAED), energy dispersive X-ray (EDX) and atomic absorption spectrophotometer (AAS) correspond to LiNi_0.5Co_0.5VO₄. V–O stretching vibrations of VO₄ tetrahedrons analyzed using FTIR and Raman spectrometer are in the range of 620–900 cm⁻¹. A solvothermal reaction at 150 °C for 10 h followed by calcination at 600 °C for 6 h yields crystals with lattice parameter of 0.8252 ± 0.0008 nm. Transmission electron microscope (TEM) images clearly show that the solvothermal temperatures play a more important role in the size formation than the reaction times.     

Large-scale synthesis of CuS hexaplates in mixed solvents using a solvothermal method

Large-scale covellite CuS hexaplates were successfully synthesized by the 200 °C solvothermal reactions of CuCl₂.2H₂O and (NH₄)₂S in C₂H₅OH-H₂O mixed solvents containing HCOOH as a pH stabilizer, including different amounts and molecular weights (MWs) of polyethylene glycol (PEG). By using XRD and SAED, CuS (hcp) was detected. XRD peaks of the product, synthesized in a solution containing 5 g PEG6000 and 1.5 ml HCOOH for 5 h, are in accordance with those of the simulation and database. The (110) peak shows the preferential growth, corresponding to the hexaplates, characterized using SEM, TEM and HRTEM. CuS hexaplates with the (100) and (010) lattice planes at an angle of 120° were detected on the flat surface, and the (002) lattice plane on the edge. UV-vis absorption edge was detected at 610 nm (2.03 eV), and the PL emission at 361 nm (3.43 eV). Phase and morphology formations were also explained according to the experimental results.     

Microwave-assisted synthesis of ZnO nanostructure flowers

Hexagonal ZnO nanostructure flowers were successfully synthesized from a 1:15 molar ratio of Zn(CH₃COO)₂2H₂O to KOH using 180 W microwave radiation for 20 min. The product phase was detected using X-ray diffraction (XRD) and selected area electron diffraction (SAED). A diffraction pattern was also simulated and was found to be in accordance with those of the experiment and the JCPDS database. Raman spectrometry revealed the presence of four vibration peaks at 337.85, 381.13, 437.54 and 583.30 cm^? 1. The product, spear-shaped nanorods in flower-like clusters, was characterized using both scanning electron microscopy (SEM) and transmission electron microscopy (TEM). High resolution TEM (HRTEM) showed that growth of the spear-shaped nanorods was in the [001] direction, which was normal to the (002) planes composing a lattice fringe of the nanorods. A formation mechanism of hexagonal ZnO nanostructure flowers was also proposed.     

Effects of ethylenediamine to water ratios on cadmium sulfide nanorods and nanoparticles produced by a solvothermal method

Cadmium sulfide nanorods and nanoparticles were successfully produced by a solvothermal reaction at 200 °C for 24 h using ethylenediamine and water as pure and mixed solvents. The products were analyzed by X-ray diffraction, Raman spectroscopy and transmission electron microscopy. In pure ethylenediamine, they show the hexagonal structure CdS nanorods with 0.2-2 μm long and 30 nm diameter, and the 1LO and 2LO modes at 299.36 and 600.72 cm^− 1, respectively. Growth of CdS nanorods is along the [001] direction, interpreted by HRTEM images and SAED patterns. In the 50:50 vol.% of ethylenediamine:water mixed solvents, the length of CdS nanorods decreased to 100-200 nm. The CdS nanoparticles were produced when pure water was used.     

Analyses of nano-crystalline LiCoVO4 prepared by solvothermal reaction

LiOH·H₂O, Co(NO₃)₂·6H₂O and NH₄VO₃ were used to prepare nano-crystalline LiCoVO₄ by 150 °C solvothermal reaction in isopropanol for 10–360 h and subsequent calcination at 300–500 °C for 6 h. XRD, TEM and selected area electron diffraction (SAED) revealed the presence of nano-crystalline LiCoVO₄ with inverse spinel structure. The V–O stretching vibration modes of VO₄ tetrahedrons were detected by FTIR over the range 617–835 cm^− 1 and by Raman spectrometer at 805.7 and 783.1 cm^− 1. Co, V and O were detected by EDX. TGA of solvothermal products shows weight loss due to the evaporation and decomposition processes at 40–648 °C.     

Cyclic microwave-assisted spray synthesis of nanostructured MnWO4

MnWO₄ with nano-plates in flower-like clusters was produced from the mists of the solutions containing MnCl₂·4H₂O and Na₂WO₄·2H₂O at different pH values by 300-900 W cyclic microwave radiation. The phase was detected by XRD and SAED, and was in accordance with that of the simulation. The flowers were characterized using SEM and TEM, and their lattice planes using HRTEM. The vibration spectra were characterized using Raman and FTIR spectrometers. Their photoluminescence is at 409-420 nm.     

Synthesis and characterization of Gd-doped PbMoO_4 nanoparticles used for UV-light-driven photocatalysis

Gd-doped PbMoO_4 nanoparticles were prepared by a refluxing method at 80℃ for 2 h.Effect of molar content of Gd dopant on phase,morphology and optical properties was studied.The as-prepared Gddoped PbMoO_4 samples can be indexed to pure tetragonal PbMoO_4 phase.The particles size of PbMoO_4 is decreased with increasing in the molar content of Gd dopant from 15.20±3.04 nm for pure PbMoO_4 to 8.72±1.53 nm for 5 mol% Gd-doped PbMoO_4.The absorption of 5 mol% Gd-doped PbMoO_4 nanoparticles shows red-shift caused by lattice distortion of PbMoO_4.The photocatalytic performance of 5 mol% Gddoped PbMoO_4 nanoparticles shows the highest degradation of rhodamine B(RhB) of 97.92% under UV radiation and 67.65% under visible radiation because Gd~(3+) dopant as an electron acceptor plays the role in enhancing the separation of electron-hole pair.     

Characterization of copper sulfide nanostructured spheres and nanotubes synthesized by microwave-assisted solvothermal method

Copper sulfide nanostructured spheres and nanotubes were successfully synthesized, using a microwave-assisted solvothermal method, by the decomposition of [Cu(CH₃CSNH₂)₂]Cl₂ complexes, formed by the reaction of CuCl₂·2H₂O and CH₃CSNH₂ in ethylene glycol at different pH values, and identified by CHNS/O and FTIR analyses. The decrease in bonding energy of N-H revealed the coordination of copper ions and thioacetamide molecules. It was specified that nitrogen atoms of thioacetamide molecules were used to form Cu-thioacetamide complexes. XRD, SEM, TEM and SAED analyses show that the products were hexagonal CuS spheres in an extremely low pH solution, and hexagonal CuS nanotubes at a pH 13. Their Raman spectra show sharp peaks at 473 cm^− 1, identified as the S-S stretching mode of S₂ ions at the 4e sites.     

Growth of hexagonal prism ZnO nanorods on Zn substrates by hydrothermal method and their photoluminescence

Hexagonal prism ZnO nanorods were successfully grown on Zn substrates by the 120 °C and 24 h hydrothermal reaction of the solutions with pH of 9–12. Results from XRD, SEM, TEM, SAED and HRTEM showed that the as-synthesized products were wurtzite ZnO with the shape of hexagonal prism nanorods grown along the [0 0 1] direction with smooth prismatic side planes. The PL spectra showed strong emission band at 543 nm in the green-yellow region due to the recombination of electrons trapped in singly ionized oxygen vacancies and photoexcited holes. This facile, reproducible and effective low-cost approach is promising for the future large-scale synthesis of wurtzite ZnO nanostructures for different applications in nanotechnology.