Simple Aqueous Solution Route Research Articles

Revealing efficient battery-type redox reaction in MOF-derived porous sponge-like Co3O4 nanoarchitecture electrode material toward next-generation energy storage device

Developing metal oxides with advanced architectures has received extensive global attention and becoming an attractive contender for achieving high-performance electrode materials for efficient energy storing systems. Herein, metal organic framework (MOF) derived porous sponge-like Co3O4 architectures have been fabricated through a simple aqueous solution route combined with thermal treatment. The sponge-like unique morphology of Co3O4 architectures affords a high surface area with the appropriate porous feature and superior electronic conductivity. Further, it offers an effective pathway to expedite electron/ion transportation and alleviate volume changes. The porous sponge-like Co3O4 electrode reveals a large specific capacity of 434 C g−1 at a current density of 1 A g−1 with promising rate capability. Furthermore, the constructed hybrid supercapacitor (HSC; Co3O4//AC) depicts an excellent electrochemical performance with a specific capacity as high as 272 C g−1 at a current density of 1 A g−1. Moreover, the HSC achieves a large specific energy of 48.19 Wh kg−1 at a specific power of 710.76 W kg−1 and cyclic retention of 90.58% after 10,000 cycles. As a result, the remarkable electrochemical performance of the porous sponge-like Co3O4 architectures could provide a new strategy as a potential candidate for next-generation energy storage applications.

Shape‐Dependent Basicity of Nanoscale La2O2CO3 Catalysts in the Dimethyl Carbonate Synthesis from Propylene Carbonate with Methanol

AbstractLa2O2CO3 as a promising solid base catalyst for transesterification reaction has been widely investigated in heterogeneous catalysis. In this study, we synthesized a series of La2O2CO3 with controllable morphologies including nanosheets, nanorods, and nanoparticles exposed different crystal facets by a simple aqueous solution route, and then then explored the shape effect of La2O2CO3 on the catalytic performance of dimethyl carbonate (DMC) synthesis from transesterification of propylene carbonate (PC) with methanol. As expected, a La2O2CO3 nanosheets catalyst had the highest turnover frequency than nanoparticles and nanorods. The observed La2O2CO3 shape effect in catalysis was associated with its basicity. Characterization results revealed that the highest amount of strong basic sites on the surface of La2O2CO3 nanosheets predominantly exposed (001) planes were responsible for the higher catalytic activity.

Facile synthesis of three-dimensional Mn3O4 hierarchical microstructures for efficient catalytic phenol oxidation with peroxymonosulfate

Hierarchical porous materials have a wide application prospect in heterogeneous catalysis because they can provide plentiful surface active sites and well-developed mass transfer channels while being easily separable, as compared with their nanosized counterparts. In this study, three-dimensional hausmannite (Mn3O4) hierarchical micron-sized materials (Mn3O4-H) were synthesized by a simple room-temperature aqueous solution route. The catalytic performance was evaluated by activation of peroxymonosulfate (PMS) to oxidize phenol, a model organic pollutant, in aqueous solution. The Mn3O4-H showed a higher efficiency in activating PMS for phenol oxidation than two Mn3O4 nanomaterials, i.e., nanoparticles and nanorods, attributed to the higher specific surface area and more surface reactive sites arising from the hierarchical structure. The Mn3O4-H also showed high catalytic stability, with low Mn leaching during phenol degradation tests. Phenol degradation reaction kinetics followed the pseudo-first-order rate laws, and the reaction was accelerated at higher temperature. In addition, the effects of important operation parameters such as catalyst loading and PMS concentration on catalytic performance of Mn3O4-H were evaluated. The present research provides a facile approach for synthesis of green and effective catalytic materials to be used in PMS-based advanced oxidation processes for environmental remediation.

Surfactant-assisted fabrication of PbS nanorice at low temperature in aqueous solution

In this work, we report the fabrication of uniform PbS nanorice via a simple aqueous solution route using cetyl trimethyl ammonium bromide (CTAB) as a surfactant at low temperature (50 °C) for 2 h. The morphology, structure and optical properties of the products were characterized by means of XRD, FESEM, TEM and UV–Vis-NIR absorption spectroscopy. The as-prepared PbS nanorice have an equatorial diameter of 45–55 nm and a length of 90–150 nm. UV–Vis-NIR absorption spectrum indicated that the sample exhibits a dramatic blue-shift. The roles of CTAB and reaction temperature in the forming of PbS nanorice were discussed. Moreover, a tentative explanation for the growth mechanism of PbS nanorice has been made.

Mesoporous WN/WO3-Composite Nanosheets for the Chemiresistive Detection of NO2 at Room Temperature

Composite materials, which can optimally use the advantages of different materials, have been studied extensively. Herein, hybrid tungsten nitride and oxide (WN/WO3) composites were prepared through a simple aqueous solution route followed by nitriding in NH3, for application as novel sensing materials. We found that the introduction of WN can improve the electrical properties of the composites, thus improving the gas sensing properties of the composites when compared with bare WO3. The highest sensing response was up to 21.3 for 100 ppb NO2 with a fast response time of ~50 s at room temperature, and the low detection limit was 1.28 ppb, which is far below the level that is immediately dangerous to life or health (IDLH) values (NO2: 20 ppm) defined by the U.S. National Institute for Occupational Safety and Health (NIOSH). In addition, the composites successfully lower the optimum temperature of WO3 from 300 °C to room temperature, and the composites-based sensor presents good long-term stability for NO2 of 100 ppb. Furthermore, a possible sensing mechanism is proposed.

Wet chemistry synthesis of ZnO crystals with hexamethylenetetramine(HMTA): Understanding the role of HMTA in the formation of ZnO crystals

ZnO crystals have been prepared via a simple aqueous solution route using zinc acetate-hexamethylenetetramine (HMTA) solution. To understand the role of HMTA in the formation processes of ZnO crystals, concentration measurements of Zn(II) remaining in the solution as well as SEM and XRD analyzes of the solid product have been made at regular intervals. The results demonstrated that the HMTA concentration has determinative effects on the growth rate of obtained ZnO products by controlling the composition of zinc complex species and mediating the transformation rate of building blocks. XRD results revealed the single phase nature with the wurtzite structure of the as prepared ZnO rods. X-ray photoelectron spectroscopy confirmed high purity of the ZnO rods. By varying the concentration of HMTA in the solution, the average size of rods was varied from 5μm to 10μm. Photoluminescence spectra indicated that the photoluminescent intensity of the emission peak at 380nm increase to different degree with increasing HMTA concentration. These results revealed that the concentration of HMTA plays a vital role to control the properties of ZnO crystals.

Simple preparation of WO3–ZnO composites with UV–Vis photocatalytic activity and energy storage ability

A series of WO3–ZnO composites with different WO3 contents was successfully prepared via a simple aqueous solution route at low temperature. The products were characterized by X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR) and UV–Vis diffuse reflectance spectra (UV–Vis DRS). Photocatalytic activity and energy storage ability of the as-prepared WO3–ZnO composites were evaluated by degradation of methyl orange in aqueous solution. Compared with pure ZnO and P25, WO3–ZnO composites show the higher degradation efficiency under UV–Vis light irradiation. After light irradiation, the maximum degradation efficiency in dark can reach 17.2% as the WO3 content of the composite is 5mol%. In addition, photocatalysis and energy storage mechanisms of the WO3–ZnO composites were discussed.

Highly efficient core–shell CuInS2–Mn doped CdS quantum dot sensitized solar cells

A simple aqueous solution route has been used to prepare mercaptoacetic acid attached CuInS2 quantum dots. Based on this material, core-shell CuInS2-Mn doped CdS quantum dot sensitized solar cells are assembled and a power conversion efficiency of 5.38% is obtained under AM1.5 (100 mW cm(-2)) illumination.

Simple Aqueous Solution Route for Fabrication of High Performance Oxide TFT

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Oxygen interstitials enhanced room temperature ferromagnetism in undoped zinc oxide

Pure zinc oxide (ZnO) particles fabricated by a simple aqueous solution route were treated with hydrogen peroxide (H2O2) solution. X-ray diffraction (XRD) and scanning electron microscopy (SEM) showed the homogeneous growth of particles throughout the substrate with the wurtzite phase. Magnetic properties were measured and a correlation between immersion time and ferromagnetism (FM) was observed. X-ray photoemission spectroscopy (XPS) and photoluminescence (PL) were then performed to investigate the influence of hydrogen peroxide (H2O2) treatment on oxygen-related defects. It is revealed that oxygen interstitials (IO) may be considered to be playing an important role in tailoring the magnetic properties of ZnO.

Facile synthesis of glass–silver nanodisk core–shell composite hollow spheres

Novel glass–silver nanodisk core–shell composite hollow spheres were successfully fabricated by a simple aqueous solution route. The effects of some reaction parameters on the morphology of the silver layers were investigated. The unique structure of the as-obtained composite makes it promisingly practicable in catalytic or sensory fields.

Fabrication of superhydrophobic surface of hierarchical ZnO thin films by using stearic acid

Flower-like hierarchical ZnO microspheres were successfully synthesized by a simple, template-free, and low-temperature aqueous solution route. The morphology and microstructure of the ZnO microspheres were examined by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The bionic films with hydrophobicity were fabricated by the hierarchical ZnO microspheres modified by stearic acid. It was found that the hydrophobicity of the thin films was very sensitive to the added amount of stearic acid. The thin films modified with 8% stearic acid took on strong superhydrophobicity with a water contact angle (CA) almost to be 178° and weak adhersion. The remarkable superhydrophobicity could be attributed to the synergistic effect of micro/nano hierarchical structure of ZnO and low surface energy of stearic acid.

Controllable synthesis of spindle-like ZnO nanostructures by a simple low-temperature aqueous solution route

Spindle-like ZnO nanostructures were successfully synthesized through direct precipitation of zinc acetate aqueous solution at 60°C. Phase structure, morphology and microstructure of the products were investigated by X-ray diffraction, TG-DTA, FTIR and field emission scanning electron microscopy (FESEM). Result showed that hexagonal wurtzite structure ZnO nanostructures with about 100nm in diameter and 100–200nm in length were obtained. HMTA acted as a soft template in the process and played an important role in the formation of spindle-like ZnO nanostructures. Meanwhile, different morphologies were also obtained by altering synthetic temperature, additional agents and the ratios of Zn2+/OH−. Possible mechanism for the variations of morphology with synthesis parameters was also discussed in this paper.

Hybrid Ag2S–Ag3SBr superionic conductor nanoparticles and their large-scale ordered arrays

We report a simple aqueous-solution route to synthesize hybrid Ag(2)S-Ag(3)SBr superionic conductor nanoparticles with faceted-spherical and polyhedral morphologies at low temperature. The morphological control was achieved by adjusting the H(+) concentration in the presence of cetyltrimethylammonium bromide, which was used as both a Br(-) source and a capping reagent. The hybrid nanoparticles could self-organize into large-scale ordered arrays, and have potential applications in fabricating photonic crystals, mixed superionic conductors, high energy density batteries and near-infrared photoluminescent devices.

Template-free synthesis, characterization, growth mechanism and photoluminescence property of Eu(OH) 3 and Eu 2O 3 nanospindles

A simple aqueous solution route was introduced for the fabrication of uniform Eu(OH) 3 and Eu 2O 3 nanospindles, nanorods and nanobundles by using Eu(NO 3) 3 and NaOH as the starting reaction reagents at room temperature and atmosphere pressure without any surfactant and template. The influence of the molar ratios of [OH −]/[Eu 3+], reaction time, and temperature was investigated. It is demonstrated that the size of Eu(OH) 3 nanospindle can be well tuned by adjusting the [Eu 3+]/[OH −] molar ratios. The possible growth mechanism of Eu(OH) 3 and Eu 2O 3 nanostructures is also discussed. The room-temperature photoluminescence analysis shows that Eu 2O 3 nanostructures have an intensive emission peak of Eu 3+ ion at around 611 nm due to the 5D 0– 7F 2 forced electric dipole transition of Eu 3+ ions. It is found that the relative peak intensity increases with increasing reaction time.

Synthesis and separation property of flower-like Cd(OH) 2 microstructures via a simple solution route

Well-defined flower-like Cd(OH) 2 microstructures have been successfully synthesized via a simple aqueous solution route, using CdCl 2 and NaOH as the reactants, and triethanolamine (TEA) as the modifying agent. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV–vis spectrometer were used to characterize the products. SEM and TEM images illustrated that the flower-like Cd(OH) 2 bundles consisted of hexagonal nanoplates with thickness of about 50 nm. The adsorption of TEA on (0 0 1) plane of the growing Cd(OH) 2 crystal leads to the flower petals in appearance. Further experiments evidenced that the positively charged Cd(OH) 2 could effectively adsorb or separate the negatively charged dye molecules.

Controllable synthesis of thioglycolic acid capped ZnS(Pn) 0.5 nanotubes via simple aqueous solution route at low temperatures and conversion to wurtzite ZnS nanorods via thermal decompose of precursor

In the present paper, we report the successful synthesis of a thioglycolic acid capped ZnS(Pn) 0.5 nanotubes (Pn = propanediamine) by a simple aqueous solution route employing ZnS(Pn) 2 and TGA as a reactant at relatively low temperature. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet–visible (UV–vis) spectroscopy, photoluminescence spectroscopy (PL), Fourier transform infrared (FT-IR) spectroscopy, and thermogravimetric-differential thermal analysis (TG-DTA). The effect of TGA concentration, on shapes and size of as-prepared product has been investigated. The thioglycolic acid capped ZnS(Pn) 0.5 nanotubes showed considerable blue shift in comparison of bulk ZnS because of quantum confinement effect.

Simple Aqueous Solution Route to Luminescent Carbogenic Dots from Carbohydrates

A simple aqueous solution route has been developed for the preparation of luminescent carbogenic dots from carbohydrates. The optical properties of the carbogenic dots can be tuned by differing the starting materials or the duration of nitric acid treatment. The multicolor emission capability and potential nontoxic nature of these carbogenic dots should enable them to find a wide range of applications in life sciences research.

Synthesis and characterization of nano-sized Ba x Sr1−x SO4 (0 ≤ x ≤ 1) solid solution by a simple surfactant-free aqueous solution route

A facile aqueous solution route has been employed to synthesize Ba x Sr1−x SO4 (0 ≤ x ≤ 1) solid solution nanocrystals at room temperature without using any surfactants or templates. The as-synthesized products were characterized by means of X-ray diffraction (XRD), X-ray fluorescence spectrometer (XRF), scanning electron microscopy (SEM), and differential scanning calorimetry-thermogravimetry (DSC-TG). The Ba x Sr1−x SO4 solid solution nanocrystals exhibit an orthorhombic structure and an ellipsoidal-shaped morphology with an average size of 80–100 nm. The lattice parameters of Ba x Sr1−x SO4 solid solution crystals increase with increasing x value. However, they are not strictly coincident with the Vegard’s law, which indicates that the as-obtained products are non-ideal solid solutions. The Ba x Sr1−x SO4 solid solution nanocrystals have an excellent thermal stability from ambient temperature to 1300°C with a structural transition from orthorhombic to cubic phase at about 1111°C.

Morphological control of ZnO particles synthesized via a new and facile aqueous solution route

Zinc oxide with a diversity of well-defined morphologies was synthesized via a simple aqueous solution route by decomposing Zn x O y (OH) z precursor at suitable reaction conditions. Flower-like ZnO composed of rods was obtained by treating Zn x O y (OH) z precursor in the reaction solution at 90 °C for 6 h. The precipitate of layer-like Zn x O y (OH) z precursor was decomposed by drying at 90 °C for 24 h in air, resulting in the formation of ZnO microtubes.