One-pot Solvothermal Route Research Articles

An easy one-pot solvothermal synthesis of poorly crystalline solid ReS2/C microspheres

Dense microspheres consisting of poorly crystalline ReS2 embedded in carbon were synthesized with a high yield via a facile one-pot solvothermal route, by reacting dirhenium decacarbonyl, elemental sulfur and an aromatic solvent (benzene, toluene or p-xylene) for 24 h at 180 °C. X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDS), Raman spectroscopy, and Fourier transform infrared spectroscopy (FT-IR) techniques were used to characterize the samples. The resulting microspheres were dense, with average diameters between 0.79 and 1.40 μm, had smooth surfaces and were constructed of ReS2 sheet-like structures with 4.5–9.8 wt % of structural amorphous carbon, which is retained as a textural stabilizer after calcination at 800 °C. The synthesis was repeated using isopropanol and cyclohexane, whose products were agglomerated grains and botryoidal quasi-spherical particles, respectively. A possible formation mechanism of ReS2/C microspheres was preliminarily presented, in order to clarify the mechanistic differences between the rhenium carbonyl and other transition metal carbonyls used in similar syntheses.

Nanosheet-assembling Hierarchical Zinc Stannate Microspheres for Enhanced Efficiency of Dye-Sensitized Solar Cells

Nanosheet-assembling hierarchical Zn2SnO4 microspheres (NHMSs) are synthesized via one-pot solvothermal route and used as photoanodes for dye-sensitized solar cells (DSSCs). An overall photoconversion efficiency of 3.43% has been achieved with this ternary metal oxide and structure, significantly higher than that derived from dispersed nanosheets (DNSs) electrode (2.06%). The hierarchical Zn2SnO4 microsphere structure is proven to be favorable for enhancement of overall dye-sensitized solar cells photoconversion efficiency via (1) the hierarchical Zn2SnO4 microspheres can function as efficient light scatters to enhance the light-harvesting efficiency; (2) intersectional contact with one another of the nanosheets of densely packed neighboring microspheres offers the transport channel for fast electron transport, avoiding the high resistance existing in the nanoparticle-based microspheres due to the relatively small interface resistance; (3) these spherical assemblies form large external pores for dye loading, at the same time, provide a “main trunk” for the quick electrolyte diffusion throughout the Zn2SnO4 layer in the film.

One-pot low temperature solvothermal synthesis of In2O3 and InOOH nanostructures

In2O3 nanopaticles/nanoflowers and InOOH nanorods were successfully synthesized via a one-pot solvothermal route at low temperature by using the suitable surfactant or simply tuning the amount of octane (C8H18). In the current work, the use of non-aqueous solvent anhydrous alcohol is a crucial factor for the formation of the In2O3 phase. Experimental results confirm that poly(N-vinylpyrrolidone) (PVP) plays a very important role in the formation process of In2O3 nanoflowers, while cetyltrimethylammonium bromide (CTAB) has no effect on the size and morphology of the final products; reaction temperature and reaction time have direct influence on the crystal phase of the final products; the amount of the solvent octane not only influences the crystal phase of the final products, but also has an obvious effect on their morphology. On the basis of our experimental results, detailed formation mechanisms for the In2O3/InOOH phase and nanostructures were proposed. The optical properties of In2O3 nanopaticles/nanoflowers were also studied.

TiO2 loaded on graphene nanosheet as reinforcer and its effect on the thermal behaviors of poly(vinyl chloride) composites

• Titanium dioxide/graphene hybrid was synthesized by a one-pot solvothermal route. • The graphene/TiO 2 hybrid was employed to enhance the properties of PVC materials. • The composite exhibited the increased glass transition temperature and storage modulus. • The HCl release rate was reduced by the addition of graphene/TiO 2 hybrid into PVC. Titanium dioxide/graphene hybrids were synthesized by a facile in situ solvothermal route and introduced to enhance the properties of the poly(vinyl chloride) (PVC) materials. X-ray diffraction and transmission electron microscopy results indicated that TiO 2 nanoparticles were homogeneously anchored on the graphene oxide nanosheets and the reduction of graphene oxide occurred simultaneously during the one-pot solvothermal process. With the incorporation of 2.0 wt% graphene/TiO 2 hybrids, a 3.5 °C increment in the glass transition temperature and a 50% increase in the storage modulus were observed compared to neat PVC. The improvement of the temperature of maximum mass loss rate and reduction of maximum mass loss rate were also observed from thermogravimetric analysis, indicating the enhanced thermal stability of PVC composites. Moreover, the reduced peak heat release rate and HCl release rate obtained from microscale combustion calorimeter and thermogravimetric analysis-infrared spectrometry indicated the superior fire safety of PVC composites. The changes of the fire behavior were primarily attributed to the synergistic effects of graphene/TiO 2 hybrids: the adsorption and barrier effect of fillers slow down the thermal degradation of polymer, and restrain the heat transfer and the flammable or toxic gaseous products release.

Size-Controlled Synthesis of BiPO4 Nanostructures and Their Photocatalytic Performances

Monoclinic phase BiPO4 nanocrystals have been synthesized in the oleic acid (OA) solution through one-pot solvothermal route. The photocatalytic performances of the BiPO4 nanocrystals were evaluated by the degradation of rhodamine B (RhB) solution under UV and visible light irradiation. The reaction rate of BiPO4 nanocrystals before calcination was 0.0509 min−1, which was much higher than that after calcination (0.0328 min−1). The BiPO4 nanocrystals before calcination exhibit higher photocatalytic activity than that after calcination. The small size of BiPO4 nanocrystals may be the key factor for its high photocatalytic performances.

TiO2 nanocrystals/graphene hybrids with enhanced Li-ion storage performance

TiO2 nanocrystals/graphene hybrids (TiO2-G) with ultrafine TiO2 nanocrystals (~7 nm in size) conformally coated on ultrathin graphene nanosheets (~ 2 layers thick) were successfully prepared via a facile one-pot solvothermal route under mediated conditions. With the feature of large surface area, abundant mesopores and high thermal stability, the TiO2-G nanohybrids exhibited large reversible Li-ion storage capacity with excellent cycling stability (629 mAh·g−1 after 400 cycles at a current of 60 mA·g−1) and good rate capability (184 mAh·g−1 at a current density of 3 A·g−1) due to the synergetic effects and strong interactions between the components, showing great promise in applications for advanced energy storage devices.

Graphene-enhanced visible-light photocatalysis of large-sized CdS particles for wastewater treatment.

The hybrid composites of graphene decorated by large-sized CdS particles (G/M-CdS) were prepared by a one-pot solvothermal route in which the reduction of graphite oxide into graphene was accompanied by the generation of microsized CdS particles. The structure and composition of the obtained nanocomposites were studied by means of X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The CdS particles with the average sizes of approximately 640 nm were formed on graphene sheets. The as-prepared composite was used as adsorbent to remove dye from wastewater using the organic dye Rhodamine B as the adsorbate. The G/M-CdS composite reveals a high photodegradation rate under visible light irradiation. Our results demonstrate that the G/M-CdS is very promising for removing organic dyes from wastewater.

One-pot controlled synthesis of sea-urchin shaped Bi2S3/CdS hierarchical heterostructures with excellent visible light photocatalytic activity

In this study, sea-urchin shaped Bi2S3/CdS hierarchical heterostructures are successfully synthesized via a convenient one-pot growth rate controlled route. The product is mainly composed of Bi2S3 nanorods and CdS nanoparticles grown on their surfaces. The formation mechanism was proposed based on the evolution of morphology as a function of solvothermal time, which involves fast formation of the initial sea-urchin shaped Bi2S3 nanoflowers, followed by the gradual growth of numerous CdS nanoparticles on Bi2S3 nanoflowers. The effects of CdS in the composites on their microstructures, optical absorption properties, and photocatalytic activity were investigated comparatively. Due to the synergetic effects between hierarchical Bi2S3 nanoflowers and CdS nanoparticles, the obtained Bi2S3/CdS hierarchical heterostructures exhibit superior catalytic activity over the independent components. Furthermore, the obtained Bi2S3/CdS hierarchical heterostructure composite shows a strong structure-induced enhancement of the photocatalytic performance for the photodegradation of rhodamine B.

Uniform iron oxide hollow spheres for high-performance delivery of insoluble anticancer drugs

As an intrinsic characteristic of many anticancer drugs, low solubility in physiological conditions limits the usage of these active ingredients in clinics. To overcome this bottleneck, we attempt to design and construct a high-performance magnetic-targeted delivery system based on uniform iron oxide hollow spheres. Via a facile one-pot solvothermal route, well-defined iron oxide hollow spheres were prepared with inexpensive inhesion. Compared with previously reported mesoporous Fe3O4 nanoparticles, our iron oxide hollow spheres have a larger void space giving the structures a higher storage capacity for guest molecules. In our present work, camptothecin (CPT) was selected as a model insoluble anticancer drug to confirm the efficiency of drug-loading and chemotherapy in vitro. Detailed anticancer efficacy was further investigated by using MTT assays and microscope imaging methods, indicating that these iron oxide hollow spheres are promising for insoluble drug delivery.

Self-assembled WO3−x hierarchical nanostructures for photothermal therapy with a 915 nm laser rather than the common 980 nm laser

Photothermal therapy (PTT) is limited by unsuitable photothermal agents and near-infrared (NIR) light. Herein, self-assembled PEGylated WO3-x hierarchical nanostructures, which could serve as excellent laser-cavity mirrors, were successfully prepared via a simple one-pot solvothermal route. The as-prepared WO3-x hierarchical nanostructures displayed strong near-infrared absorption. The absorption of pure water at 980 nm is 30 times higher than that at 915 nm, and the temperature of water only increased by 3.4 °C under the irradiation of a 915 nm laser with a power density of 1.0 W cm(-2) for 10 min, while the temperature of water increased as much as 15.1 °C for the 980 nm laser. With continuous excitation by 915 nm light, the photothermal conversion efficiency of these WO3-x hierarchical nanostructures was evaluated to be 28.1%. Thus, the WO3-x hierarchical nanostructures could serve as excellent laser-cavity mirrors of a 915 nm laser. The PTT study on cancer cells in vivo demonstrated that the WO3-x hierarchical nanostructures can generate enough heat for efficient photothermal therapy of cancer cells under the irradiation of a 915 nm laser with a power density of 1.2 W cm(-2) over a short period (5-10 min).

Controllable synthesis of plasmonic Ag/AgBr photocatalysts by a facile one-pot solvothermal route

Plasmonic photocatalysts Ag/AgBr composites were synthesized by a facile one-step solvothermal route. Unlike the traditional photoreduction method, metallic Ag in the present work was in situ anchored on the surface of AgBr by reducing radicals created through the thermal process. The structures (e.g., particle size, composition, and dispersion) of metallic Ag nanoparticles could be well controlled by simply changing the reaction temperature and solvent. The as-prepared composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and diffuse reflectance spectra (DRS). The as-prepared Ag/AgBr composites exhibited excellent photocatalytic efficiency for the degradation of azo dye methyl orange (MO), phenol, and 2-chlorophenol under visible light irradiation. It was found that the activity was highly dependent on the particle size, composition and the dispersing extent of Ag nanoparticles. The photocatalytic mechanism was studied by radical-trapping experiments and the photoluminescence (PL) technique with terephthalic acid, and the results indicated that O2- and h+ played great roles in the rapid degradation of organic pollutants under visible light irradiation.

Direct visualization of gastrointestinal tract with lanthanide-doped BaYbF5 upconversion nanoprobes

Nanoparticulate contrast agents have attracted a great deal of attention along with the rapid development of modern medicine. Here, a binary contrast agent based on PAA modified BaYbF5:Tm nanoparticles for direct visualization of gastrointestinal (GI) tract has been designed and developed via a one-pot solvothermal route. By taking advantages of excellent colloidal stability, low cytotoxicity, and neglectable hemolysis of these well-designed nanoparticles, their feasibility as a multi-modal contrast agent for GI tract was intensively investigated. Significant enhancement of contrast efficacy relative to clinical barium meal and iodine-based contrast agent was evaluated via X-ray imaging and CT imaging in vivo. By doping Tm3+ ions into these nanoprobes, in vivo NIR–NIR imaging was then demonstrated. Unlike some invasive imaging modalities, non-invasive imaging strategy including X-ray imaging, CT imaging, and UCL imaging for GI tract could extremely reduce the painlessness to patients, effectively facilitate imaging procedure, as well as rationality economize diagnostic time. Critical to clinical applications, long-term toxicity of our contrast agent was additionally investigated in detail, indicating their overall safety. Based on our results, PAA-BaYbF5:Tm nanoparticles were the excellent multi-modal contrast agent to integrate X-ray imaging, CT imaging, and UCL imaging for direct visualization of GI tract with low systemic toxicity.

Preparation of tin sulfide–graphene composites with enhanced lithium storage

Tin sulfide–graphene nanocomposites have been synthesized through a facile one-pot solvothermal route. The as-prepared composites are characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Brunauer–Emmett–Teller analysis and elemental analysis. The results indicate that tin sulfide nanoparticles are homogeneously anchored on the surface of graphene. The electrochemical performance of tin sulfide–graphene composites is evaluated by galvanostatic charge–discharge tests and electrochemical impedance spectroscopy. Results show that the composites exhibit enhanced reversible lithium storage properties with high reversible capacity and good cyclic performance. The method presented in this work may provide a facile and economic strategy for the preparation of metal sulfide–graphene composites.

Ethylene glycol-mediated direct synthesis of nanostructured nickel oxide–carbon composite material on nickel foam and its electrochemical property

A convenient ethylene glycol (EG)-mediated one-pot solvothermal route was designed for direct synthesis of nanostructured nickel oxide-carbon composite material on nickel foam. EG was employed as solvent, complex agent and carbon source. Furthermore, cyclic voltammetry and constant current charge-discharge measurements confirmed that the composite material electrode displayed good electrochemical activity with a maximum specific capacitance of 539 F g -1 at a current density of 0.25 A g -1 .

Hierarchical BiOI and hollow Bi2WO6 microspheres: Topochemical conversion and photocatalytic activities

We present here a facile one-pot surfactant-free solvothermal route to synthesize hierarchical BiOI microspheres assembled from nanosheets at 120 °C for 16 h. The as-synthesized BiOI microspheres could be topochemically converted into hollow hierarchical Bi2WO6 ones built by nanoplates for the first time under hydrothermal condition because of the analogies of crystal structures. The transformation process of hierarchical BiOI microspheres to hollow Bi2WO6 ones was surveyed through XRD analyses and FE-SEM observations of the intermediates at different reaction stages. Rhodamine B (RhB) was selected as pollutant model and visible-light-driven photocatalytic activities of hierarchical BiOI and Bi2WO6 microspheres under the same measurement conditions were comparatively studied. As a result, the photocatalytic activities of BiOI obviously outshone Bi2WO6. The present study not only develops a new method for fabricating hierarchical architectures but also provides some useful information on relative visible-light-responding photocatalytic activity of hierarchical BiOI and Bi2WO6 microspheres.

Synthesis and electrochemical performances of cobalt sulfides/graphene nanocomposite as anode material of Li-ion battery

The cobalt sulfides/graphene nanosheets (GNS) composite is prepared by a facile one-pot solvothermal route in the presence of graphene oxide sheets (GOS). XRD, SEM and TEM characterizations show that sphere-like cobalt sulfides particles with an average size of about 150 nm, which are complicated phases of CoS2, CoS and Co9S8, are highly dispersed on or wrapped in the creasy graphene. The selective nucleation and growth of cobalt sulfides particles on GOS make the particles more uniform in morphology and size. The as-fabricated cobalt sulfides/GNS composite exhibits very high electrochemical lithium storage reversible capacity of about 1018 mAh g−1. Moreover, the cobalt sulfides/GNS composite still remains reversible capacity of above 950 mAh g−1 after 50 cycles at a current density of 100 mA g−1 as well as at the different current densities from 100 to 1000 mA g−1, proving its excellent cycling durability and high-rate capability. The superior electrochemical performances of the composite may be attributed to the robust composite structure and superior conductivity, high charger mobility, large surface area and good flexibility of graphene.

Porous Ni/β-Ni(OH)2 superstructures: Rapid solvothermal synthesis, characterization, and electrochemical property

The porous Ni/β-Ni(OH)2 superstructures have been successfully prepared via a simple, fast one-pot solvothermal route in the presence of cetyltrimethyl ammonium bromide (CTAB), using NiCl2·6H2O and NaBH4 as the original reactants. The reaction was carried out in ethylene glycol at 170°C for 1h. The morphology of the obtained product could be controlled by adjusting the reaction time and the surfactant. The products were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectrometry (EDS), Infrared (IR) spectrometry, and Brunauer–Emmett–Teller (BET). The electrochemical property of the as-obtained superstructures was investigated through the cyclic voltammogram (CV) measurements. It was found that the as-obtained porous Ni/β-Ni(OH)2 superstructures exhibited good electrochemical properties and could be used as electrochemical sensors for the detection of some organic small molecules such as hydrochinone, pyrocatechol, and glucose.

A novel composite photocatalyst based on in situ growth of ultrathin tungsten oxide nanowires on graphene oxide sheets

Graphene oxide sheets were initially prepared by a modified pressurized oxidation method. Through a one-pot solvothermal route, a novel composite photocatalyst based on in situ growth of ultrathin W18O49 nanowires with diameters of 2–3 nm on graphene oxide sheets was then successfully fabricated. The as-prepared graphene oxide sheets and W18O49–reduced graphene oxide composite have been systematically characterized by combined techniques of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman microscopy, X-ray photoelectron spectrometry, and UV-vis diffuse reflectance spectroscopy. Compared to the W18O49 nanoflowers prepared in the absence of graphene oxide sheets, the W18O49–reduced graphene oxide composite exhibited significantly enhanced photocatalytic properties for the decomposition of methyl orange solution and for the growth inhibition of V. natriegens under full spectrum light, which is mainly due to the strong coupling interaction between the W18O49 nanowires and the reduced graphene oxide sheets. The present solvothermal process simultaneously enables the reduction of graphene oxide and the formation of W18O49, making it suitable for the preparation of other graphene-based composites.

Enhanced thermoelectric properties of p-type CoSb3/graphene nanocomposite

Nanostructuring and second phase incorporation are considered to be promising ways of enhancing the thermoelectric performance of bulk materials. Here, a design principle is proposed which combines these two methods for improving the thermoelectric performance of p-type CoSb3 by fabricating a CoSb3/graphene (CoSb3/G) nanocomposite, where a second phase, graphene, is introduced in the nanostructured CoSb3 matrix via an in situ one-pot solvothermal route. In addition, CoSb3/G bulk materials were prepared by hot pressing the solvothermally synthesized CoSb3/G powder. It was found that addition of a small amount of graphene can drastically enhance the electrical conductivity due to the increase in both carrier concentration and mobility. In addition, the well dispersed graphene in the nanostructured CoSb3 matrix also contributes to the low lattice thermal conductivity. A dimensionless figure of merit ZT = 0.61 at 800 K has been obtained for the CoSb3/G nanocomposite, which is about a 130% improvement over that of graphene-free CoSb3 (∼0.26).

Facile synthesis of ultrafine CoSn2nanocrystals anchored on graphene by one-pot route and the improved electrochemical Li-storage properties

In this work, we succeeded in the synthesis of a CoSn2-nanocrystals/graphene-nanosheets (CoSn2/G) hybrid by a facile in situ one-pot solvothermal route. X-ray diffraction, X-ray photoelectron spectroscopy and Raman spectra results revealed the formation of CoSn2 and the reduction of graphite oxide (GO) to graphene during the one-pot process. Transmission electron microscopy observation indicated that the spherical CoSn2 nanocrystals, with a uniform size of 2–4 nm, are anchored on graphene. The electrochemical tests showed that the CoSn2/G hybrid exhibits obviously improved electrochemical properties compared to the bare Co–Sn alloy prepared by a similar route in the absence of GO, even though the content of graphene is only 7.2 wt%. The enhancement in the electrochemical properties could be attributed to the introduction of graphene that not only constructs two-dimensional conductive networks but also disperses and confines the CoSn2 nanocrystals, in addition to the buffering effect for the large volume changes.