Single-step Hydrothermal Synthesis Research Articles

Two-step sputter-hydrothermal synthesis of NaTaO3 thin films

NaTaO3 has received considerable interest because of its extraordinary photocatalytic water splitting capability and it has been suggested for thermoelectric applications. The ability to synthesize NaTaO3 films is essential for characterization with electrochemical or scanning probe techniques that are difficult to apply to powders. Here we find that with the existing single-step hydrothermal synthesis method for NaTaO3 films, detrimental precursor etching can occur, leading to rapidly disintegrating films. We solved this problem by creating a two-step synthesis. In the first step, a Ta2O5 film is deposited, and in the second step, the Ta2O5 is hydrothermally converted into NaTaO3. With this modification, we systematically obtained durable thin films. When decreasing the synthesis temperature in steps from 393K to 343K, the crystallites gradually change from cubic to more rounded. Hence, the method enables specific control over the surface morphology of the NaTaO3 films. In addition, we show that the samples obtained with the proposed method are sufficiently flat for application of scanning probe microscopy methods.

Spatially branched CdS–Bi2S3 heteroarchitecture: single step hydrothermal synthesis approach with enhanced field emission performance and highly responsive broadband photodetection

This report explores the controlled hierarchical synthesis of CdS nanostructure branches on Bi2S3 nanorod cores via a facile single step hydrothermal route for field emission and photo detector applications.

Controlled synthesis of yttrium gallium garnet spherical nanostructures modified by silver oxide nanoparticles for enhanced photocatalytic properties

Spherical yttrium gallium garnet (Y3Ga5O12) samples were prepared by a single-step hydrothermal synthesis method, and these particles were coated with silver oxide (Ag2O) nanoparticles by following a facile wet chemical approach at ambient temperature. The structural, morphological, vibrational and optical properties of the as-prepared and Ag2O modified Y3Ga5O12 samples were analyzed. From Rietveld refinement of X-ray diffraction patterns, the crystal structure of the Y3Ga5O12 sample was refined. The morphological properties confirmed that the particles were spherical and their surfaces were covered with Ag2O nanoparticles. The Ag2O modified Y3Ga5O12 sample exhibited a relatively enhanced photocatalytic activity compared to the pure Y3Ga5O12 sample in Rhodamine B solution, suggesting that the introduction of Ag2O broadens the absorption of light and controls the photogenerated carrier recombination in Y3Ga5O12. These results provide a clear perspective on the synthesis of hybrid photocatalyst materials which have several ways of photogenerated carrier migration.

Facile Synthesis of Hierarchically Structured Bi2S3/Bi2WO6 Photocatalysts for Highly Efficient Reduction of Cr(VI)

Varied morphologies and compositions of bismuth tungstate nanocomposites have been investigated as promising materials for photocatalytic applications. Among these nanocomposites, hierarchically structured bismuth sulfide (Bi2S3)/bismuth tungstate (Bi2WO6) hybrids have significant photocatalytic efficiency toward heavy metal ions. To simplify the synthetic procedure for this desirable composite, we developed a robust single-step hydrothermal synthesis for the formation of hierarchically structured heterocatalysts of Bi2S3/Bi2WO6 with a high yield (>95%). The synthesized heterostructures were characterized by various spectroscopic, microscopic, and surface area analysis techniques, which confirmed the successful incorporation of Bi2S3 into the Bi2WO6 matrix and were used to optimize pore size for enhanced catalytic activity. The resulting Bi2S3/Bi2WO6 heterocatalysts were used to remove toxic Cr(VI) ions via reduction to water insoluble Cr(III) utilizing visible-light irradiation. We also investigated the ...

水热条件下C-O-P键的形成

Glycerol phosphates were abiotically synthesized under hydrothermally mimicked conditions with glycerol and ammonium dihydrogen phosphate. Inorganic phosphorus was therefore incorporated into biological molecule,leading to the formation of C—O—P bonds. Some factors affecting the yields of the products were taken into account. The best yield(molar fraction) of C—O—P bonds through single-step hydrothermal synthesis is ca 1. 15%.

Single step hydrothermal synthesis of hierarchical TiO2 microflowers with radially assembled nanorods for enhanced photovoltaic performance

Herein, 3D hierarchical TiO2 microflowers with a well faceted profile and high crystallinity were successfully obtained via a surfactant directed single step facile hydrothermal technique.

The first depleted heterojunction TiO2-MOF-based solar cell.

A single-step hydrothermal synthesis of a TiO2-Mil-125 composite was applied for the first time to produce a depleted perovskite/TiO2-MOF heterojunction solar cell with 6.4% power conversion efficiency (PCE), characterized by durable stability in air.

Structures and Magnetism of the Rare-Earth Orthochromite Perovskite Solid Solution LaxSm1–xCrO3

A new mixed rare-earth orthochromite series, LaxSm1-xCrO3, prepared through single-step hydrothermal synthesis is reported. Solid solutions (x = 0, 0.25, 0.5, 0.625, 0.75, 0.875, and 1.0) were prepared by the hydrothermal treatment of amorphous mixed-metal hydroxides at 370 °C for 48 h. Transmission electron microscopy (TEM) reveals the formation of highly crystalline particles with dendritic-like morphologies. Rietveld refinements against high-resolution powder X-ray diffraction (PXRD) data show that the distorted perovskite structures are described by the orthorhombic space group Pnma over the full composition range. Unit cell volumes and Cr-O-Cr bond angles decrease monotonically with increasing samarium content, consistent with the presence of the smaller lanthanide in the structure. Raman spectroscopy confirms the formation of solid solutions, the degree of their structural distortion. With the aid of shell-model calculations the complex mixing of Raman modes below 250 cm(-1) is clarified. Magnetometry as a function of temperature reveals the onset of low-temperature antiferromagnetic ordering of Cr(3+) spins with weak ferromagnetic component at Néel temperatures (TN) that scale linearly with unit cell volume and structural distortion. Coupling effects between Cr(3+) and Sm(3+) ions are examined with enhanced susceptibilities below TN due to polarization of Sm(3+) moments. At low temperatures the Cr(3+) sublattice is shown to undergo a second-order spin reorientation observed as a rapid decrease of susceptibility.

Single step hydrothermal synthesis of 3D urchin like structures of AACH and aluminum oxide with thin nano-spikes

3D urchins like ammonium aluminum carbonate hydroxide (AACH) nanostructures with nano-spikes of dia. 20–30nm were synthesized by a simple, single step hydrothermal technique by using aluminum nitrate and urea as precursor materials. It was found that morphology of the produced structure strongly depends upon the urea concentration. With increasing the amount of urea, the AACH particles having embedded rods like surface features transformed into 3D urchins. The added urea decomposed during hydrothermal treatment and increased the pH of the solution, which affected the morphology of the produced nanostructures. SEM, XRD, FTIR and TGA were employed to characterize the produced structures. On heating, the volatile ingredients of AACH were removed, leaving behind the alumina urchins.

Controlled synthesis and photoelectrochemical properties of highly ordered TiO2 nanorods

Highly ordered TiO2 nanorods (NRs) were grown directly on fluorine doped tin oxide (FTO) substrate by a single step hydrothermal synthesis at 150 °C. The morphology of TiO2 was significantly altered by changing the solvents of ethanol/deionized (DI) water as the precursor solutions. With ethanol/DI water (80 : 20 v/v) as solvent, the highly ordered tetragonal TiO2 NRs were achieved on FTO substrates with the average lengths of ∼2–4 μm and diameters ∼50–70 nm respectively. While, the round headed and distorted hexagonal TiO2 NRs were formed with ethanol/DI water ratios of 50 : 50 v/v and 0 : 100 v/v as the precursor solutions respectively. The grown TiO2 NRs possessed the anatase phase with typical tetragonal crystal structures. XPS studies evidenced that the grown TiO2 NRs exhibited the O : Ti stoichiometric ratio of 2 : 1 with lower impurities of the carbon species. The grown TiO2 NRs thin film substrates were applied as photoanodes for efficient dye-sensitized solar cells (DSSCs). A solar-to-electricity conversion efficiency of ∼3.2% was achieved by DSSC, fabricated with highly ordered tetragonal TiO2 NRs photoanode, whereas DSSC with the distorted hexagonal TiO2 NRs photoanode showed inferior overall conversion efficiency (∼1.08%). The improved photovoltaic performance was credited to the highly ordered morphology of the TiO2 NRs, which executed the high charge collection and the transfer of electrons at the interfaces of the TiO2 NRs photoanode and the electrolyte layer.

Visible light assisted photocatalytic hydrogen generation and organic dye degradation by CdS–metal oxide hybrids in presence of graphene oxide

Single step hydrothermal synthesis of CdS/Oxide (Oxide = ZnO, Al2O3) was demonstrated and examines their photocatalytic activity in presence of graphene oxide (GO). CdS/Al2O3/GO and CdS/ZnO/GO both exhibits enhanced photocatalytic activity for hydrogen generation with apparent quantum yields (AQY) of 14% and 30% respectively. Moreover, CdS/Oxide/GO displayed efficient photodegradation of an organic dye; ∼90% for CdS/Al2O3/GO and ∼99% for CdS/ZnO/GO within 60 min of time interval. Superior photocatalytic properties are attributed to the enhanced surface area and effective separation of photoinduced charge carriers due to the presence of GO. The present study highlights the potential application of graphene based materials in the field of energy conversion and environment remediation.

Tunable and rapid crystallisation of phase pure Bi 2MoO 6 (koechlinite) and Bi 2Mo 3O 12 via continuous hydrothermal synthesis

Herein, we report the rapid single step hydrothermal synthesis of phase pure Bi 2MoO 6 (koechlinite) and Bi 2Mo 3O 12, via a continuous hydrothermal flow synthesis (CHFS) reactor, which uses supercritical water of 375–450 °C at a pressure of 24.1 MPa as a crystallising medium. The product being obtained as highly crystalline nano-materials with high surface area. Simple variation in synthesis condition and appropriate solution stoichiometry were shown to be sufficient to select the phase of the product. The materials synthesised showed significant photcatalytic activity towards the decolourisation of methylene blue in comparison to a commercial gold standard photocatalyst.

Hydrothermal synthesis of single-crystalline nanocubes of Co3O4

The single step hydrothermal synthesis of well-dispersed cobalto-cobaltic oxide (Co3O4) cubic nanocrystals has been reported. Microstructure and phase have been unambiguously characterized by XRD, TEM and Raman spectroscopy. Powder X-ray diffraction (XRD) and Raman spectrum showed that the as-prepared sample was of cubic spinel structure. Transmission electron microscopy indicated that the Co3O4 nanocrystals were cubical with the crystallite size in the range of 20–30 nm. Since the particle size of the powdered samples were found to be equivalent from both TEM and X-ray diffraction technique, it can be expected that the nanocubes are single crystalline. The average BET surface area was found to be 75 m2 g−1 and the average pore diameter was found to be 15 nm.