Zn(II)-PEG 300 globules as soft template for the synthesis of hexagonal ZnO micronuts by the hydrothermal reaction method

PEG-PVP-Assisted Hydrothermal Synthesis and Electrochemical Performance of N-Doped MoS2/C Composites as Anode Material for Lithium-Ion Batteries

Molybdenum disulfide shows promise as an anode material for lithium-ion batteries. However, its commercial potential has been constrained due to the poor conductivity and significant volume expansion during the charge/discharge cycles. To address these issues, in this study, N-doped MoS2/C composites (NMC) were prepared via an enhanced hydrothermal method, using ammonium molybdate and thiourea as molybdenum and sulfur sources, respectively. Polyethylene glycol 400 (PEG400) and polyvinylpyrrolidone (PVP) were added in the hydrothermal procedure as soft template surfactants and nitrogen/carbon sources. The crystal structure, morphology, elemental composition, and surface valence state of the N-doped MoS2/C composites were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS), respectively. The results indicate that the NMC prepared by this method are spherical particles with a nanoflower-like structure composed of MoS2 flakes, having an average particle size of about 500 nm. XPS analysis shows the existence of C and N elements in the samples as C-N, C-C, and pyrrolic N. As anodes for LIBs, the NMC without annealing deliver an initial discharge capacity of 548.2 mAh·g-1 at a current density of 500 mA·g-1. However, this capacity decays in the following cycles with a discharge capacity of 66.4 mAh·g-1 and a capacity retention rate of only 12% after 50 cycles. In contrast, the electrochemical properties of the counterparts are enhanced after annealing, which exhibits an initial discharge capacity of 575.9 mAh·g-1 and an ultimate discharge capacity of 669.2 mAh·g-1 after 70 cycles. The capacity retention rate decreases initially but later increases and elevated afterward to reach 116% at the 70th cycle, indicating an improvement in charge-discharge performance. The specimens after annealing have a smaller impedance, which indicates better charge transport and lithium-ion diffusion performance.

Facile fabrication of sponge-like hierarchically porous Ni,La–SrTiO3 templated by in situ generated carbon deposits and the enhanced visible-light photocatalytic activity

Hierarchical pore-induced multiple internal reflections and/or scattering of light improves the capability of light trapping and thus photocatalytic efficiency.

C-doped ZnO ball-in-ball hollow microspheres for efficient photocatalytic and photoelectrochemical applications

ZnO is an important semiconductor and has been widely used in the field of photocatalysis, solar cell and environmental remediation. Herein, we fabricated C-doped ZnO ball-in-ball hollow microspheres (BHMs) by a facile solvothermal treatment of zinc acetate in ethylene glycol-ethanol mixture. The presence of ethylene glycol (EG) leads to the formation of initial single-layered hollow spheres and then a time-dependent evolution transforms them into uniform BHMs with tunable shell thickness and void space. XPS characterizations reveal that C-dopants are introduced into the lattice of ZnO BHMs, with its concentration increasing with solvothermal time and then becoming saturated in 12h. ZEG-12 (ZnO BHMs with 12-h solvothermal treatment), with an optimal hollow structure and C-doping concentration, performs the best optical absorption capability, efficiency of charge separation and transfer, and mass transfer in reaction media, as proved by SEM, TEM, PL, BET and EIS characterizations. When applied as photocatalyst for organic-pollutant degradation and as photoanode material for PEC water splitting, ZEG-12 exhibits respectively ca. 8.9-fold and 10.5-fold higher activity than pristine ZnO nanoparticles.

Synthesis and Characterization of Gd₂O₃ Hollow Microspheres Using a Template-Directed Method

Uniform rare-earth gadolinium oxide (Gd₂O₃) hollow microspheres, as formed through a urea-assisted homogenous precipitation process using carbon spheres as a template and a subsequent heat treatment, were characterized by using X-ray diffraction, Fourier transformed infared spectroscopy, thermogravimetry, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy and Brunauer-Emmett-Tellet surface area measurement. The results indicate that the final products can be indexed to a cubic Gd₂O₃ phase with high purity and have a uniform morphology at 500 nm in diameter and 20 nm in shell thickness. The as-synthesized Gd₂O₃ hollow microspheres exhibited a superior photooxidation activity to that of Gd₂O₃ powder and an effect similar to P25, significantly broadening the potential of Gd₂O₃ hollow microspheres for many practical applications.

Metastable γ-Bi2O3 tetrahedra: Phase-transition dominated by polyethylene glycol, photoluminescence and implications for internal structure by etch

Metastable γ-Bi2O3 tetrahedra have been fabricated by a facile polyethylene glycol-assistance (PEG, Mw=400) one-step precipitation method at 70°C. The tetrahedra of 8μm are built up of ultrathin nanosheets via layer-by-layer self-assembly. X-ray powder diffraction, scanning electron microscopy, UV-visible spectrometer and fluorescence spectrophotometer were employed to characterize the obtained γ-Bi2O3. The morphology of the γ-Bi2O3 is significantly influenced by the feeding concentration of NaOH solution. Tetrahedra and incomplete tetrahedra whose edges are clipped in various degrees of γ-Bi2O3 can be obtained with different concentrations of NaOH solution. The uniform and ordered chains of PEG play a crucial role not only in the morphology, even more important in phase-transition of Bi2O3. The photoluminescence (PL) characteristic of the sample was investigated.

Silica/titania sandwich-like mesoporous nanosheets embedded with metal nanoparticles templated by hyperbranched poly(ether amine) (hPEA)

We here demonstrated a novel square silica/titania mesoporous nanosheet which was prepared with hyperbranched poly(ether amine) nanosheets (hPEA-NSs) as a template. TEM and SEM images reveal that the obtained nanosheets possess a large aspect ratio with the average edge length of 1-2 μm and thickness of ~40 nm, respectively. Various metal nanoparticles such as gold, silver, and platinum can be embedded into these nanosheets with hPEA-NSs decorated with the corresponding nanoparticles as templates. These nanosheets possess a sandwich-like structure, which is comprised of amorphous SiO2 as the inner layer, and the anatase TiO2 as the outer layer determined by a cross-sectional STEM image and EDS mapping. Meanwhile, the obtained nanosheets are mesoporous with a high surface area (~429 m(2) g(-1)), and the SiO2 inner layer can be removed by chemical etching with NaOH solution to obtain anatase TiO2 nanosheet-like boxes embedded with gold nanoparticles (AuNPs). The photodegradation of Methyl Orange (MO) by the obtained nanosheets can be enhanced by the embedding of AuNPs owing to the localized surface plasmon resonance (LSPR) effect from AuNPs. The preparation of a silica/titania mesoporous nanosheet with hPEA-NSs as template is believed to provide a convenient and general method to produce various square inorganic mesoporous nanosheets with a large aspect ratio between edge length and thickness.

Synthesis of mesoporous β-Ga2O3 nanorods using PEG as template: preparation, characterization and photocatalytic properties

Mesoporous wide bandgap semiconductors offer high photocatalytic oxidation and mineralization activities. In this study, mesoporous β-Ga(2)O(3) diamond nanorods with 200-300 nm in diameter and 1.0-1.2 μm in length were synthesized via a urea-based hydrothermal method using polyethylene glycol (PEG) as template agent. The UV photocatalytic oxidation activity of β-Ga(2)O(3) for gaseous toluene was evaluated, and 7 kinds of intermediates were monitored online by a proton transfer reaction mass spectrometry. Photoluminescence spectra manifested that the dosage and molecular weight of PEG are crucial for formation of vacancies and photocatalytic oxidation activities. A PEG-assisted hydrothermal formation mechanism of mesoporous β-Ga(2)O(3) diamond nanorods was proposed. Based on the health risk influence index (η) of the intermediates, the calculated health risks revealed that the β-Ga(2)O(3) nanorods with a η value of 9.6 are much safer than TiO(2) (η = 17.6).

Studies on the evolution of ZnO morphologies in a thermohydrolysis technique and evaluation of their functional properties

The transformation of ZnO morphologies in an in situ thermohydrolysis technique using hexamethylene tetramine is studied with and without surfactants. The photocatalytic and photoluminescence properties of these morphologically tuned ZnO morphologies are studied and the results presented. In the absence of any surfactants, the HMTA assisted in situ hydrolysis resulted in microtube and multipod morphologies. The addition of nonionic [Span-80] and cationic [CTAB] surfactants transforms the morphologies to microspheres, microdiscs and nanorods. The photoluminescence analysis shows a red luminescence in nanorods and green-indigo and blue-green emissions in microtubes and other morphologies. Photocatalytic reaction efficiency in UV light follows the order microtubes>nanorods>microdiscs>microspheres>multipods.