One-step Microwave Method Research Articles

Highly emissive and color-tunable copper-based halide composites for bright white light-emitting diodes

The blue-emissive Cs3Cu2I5, yellow-emissive CsCu2I3, and white-emissive Cs3Cu2I5@CsCu2I3 composites have been obtained by a one-step microwave method. The three UV-pumped WLEDs are fabricated by using the composites, and a CRI of 92 is achieved.

One-Step Microwave Method Synthesis of Fe2o3 Nanoribbon@ Carbon Composite for Cr (Ⅵ) Removal

One-Step Microwave Method Synthesis of Fe2o3 Nanoribbon@ Carbon Composite for Cr (Ⅵ) Removal

One-step microwave synthesis of self-supported CoSe2@NiSe2 nanoflowers on 3D nickel foam for high performance supercapacitors

The work reports the fabrication of CoSe2@NiSe2 nanoflowers on nickel foam substrates via one-step microwave method, in which the Ni foam serves as a skeleton and a nickel source. The as-prepared CoSe2@NiSe2 nanoflowers display high capacitance value of 1434 F g−1 at the current density of 1 A g−1 and excellent cycling performance of 87.5% retention after 20,000 cycles at 10 A g−1. In addition, the supercapacitor device using CoSe2 @NiSe2 nanoflowers as the positive electrode and activated carbon (AC) as the negative electrode not only can exhibit wide voltage window of 1.6 V, but also deliver a maximum high energy density of 20.4 Wh Kg−1 at power density of 798 W Kg−1 and 86.6% of capacity retention after 20,000 cycles.

An enhanced capacitive storage of hybrid supercapacitor based on interconnected nitrogen-doped graphene encapsulated honeycomb cobalt manganese pyrophosphate

Herein, the circular ring-like cobalt manganese pyrophosphate (Co0.55Mn0.45)2P2O7 wrapped by nitrogen-doped graphene (NG) are synthetized through a facile one-step microwave method with numerous open porous structures as electrochemically active sites. The circular ring-like (Co0.55Mn0.45)2P2O7 possess honeycomb-like structures to storage more ions and have more electrochemically active sites from the honeycomb edges, which faster ion/electron transporting through the pores. Therefore, these honeycomb-like hybrids obtain an excellent specific capacity of 236.21 mA h g−1 at 1 A·g−1 under three-electrode conditions, contribution a wonderful cycle stability of 86.7% after 10,000 cycles. Anode material of asymmetric supercapacitor (ASC) is assembled with biomass hierarchical glucose carbon (HGC), the maximum energy density of the ASC device is 75.72 Wh·kg−1 at a power density of 800 W·kg−1 (remained 60.08 Wh·kg−1 at 8000 W·kg−1). The enhanced capacitive storage of the ASC device can be attributed to the interconnected circular ring-like structure and the perfect combination of nitrogen-doped graphene.

Ultrafast synthesis of anatase TiO2 microspheres doped with rare-earth by one-step microwave method

Using a one-step microwave method without any further calcination, various rare-earth (Re) ions doped anatase titania microspheres were synthesized successfully in less than 10 min. TiCl4 aqueous solution and rare-earth salt solution are used as reactant, and ethanol was used as solvent. Anatase titania microspheres doped with rare-earth ions including Ce(IV), Sm(III), Tm(III) and Tb(III) were obtained without using any template or surfactant. The scanning electron microscopy images show that the particles have well-defined spherical shapes with a relatively narrow size distribution. X-ray diffraction and Raman spectra demonstrate the crystalline phase of the particles to be anatase. The energy-dispersive spectroscopy spectra and elemental mapping identify rare earth elementals distribute in the microspheres uniformly. The valence state of rare-earth in the samples was determined by X-ray photoelectron spectroscopy spectra. The studies provide a super-rapid method to prepare rare earth doped crystalline TiO2 microspheres, which are useful materials for optical, biological and environmental applications.

One-step microwave-assisted solvothermal nano-manufacturing of Ni2P nanosphere as high-performance supercapacitors

Ni2P nanospheres were prepared by an ultrafast (120 s), easy, and energy-efficient one-step microwave method. By controlling the reaction conditions and feed ratio, Ni2P nanospheres with novel nanostructures and ultra-high electrochemical properties were prepared. These nanospheres demonstrated a high specific capacitance of 404.2 F g−1 at 1 A g−1 and high cycling durability. They maintain 81% of their initial capacity after 2000 cycles at 6 A g−1. The optimum device based on Ni2P//AC showed an outstanding energy density of 27.2 Wh kg−1 and power density of 375 W kg−1. A method that is much faster and much more energy-efficient than other approaches was developed to produce transition metal phosphates without atmosphere protection.Graphical abstract

The microwave synthesis of porous CoSe2 nanosheets for super cycling performance supercapacitors

Porous CoSe2 nanosheets prepared via a one-step microwave method can be considered as an excellent electrode material.

Selective adsorption and separation of stevioside and rebaudioside A by a metal-organic framework with boronic acid

The boronic acid functionalization metal-organic frameworks (MOFs), as unique boronate affinity adsorbents, have desired specific molecular affinity for the separation and enrichment of cis-diol-compounds. Herein, the boronic acid functionalized Zn-based MOF adsorbent (MOF-BA) was synthesized through a simple one-step microwave method and used for the recognition and isolation of steviol glycosides (SGs). This MOF-BA exhibits the same spherical structure and isostructure with the parent framework composed only of the primitive ligand as verified by SEM and XRD characterization. It was confirmed that changing the ratio of ligands could achieve the adjustability of the boron content in the framework. At the same time, the MOF-BA-1.0 showed a suitable pore size (4.69 nm), and the presence of boric acid functional groups showed favorable selectivity for stevioside (STV). The static adsorption results showed that adsorption performances of rebaudioside A (RA) and STV from crude sugar solution (5.0 mg mL−1, pH 8) on MOF-BA-1.0 were investigated at 303 K for 15 h. The adsorption capacities for STV and RA were 42.93 mg g−1 and 22.96 mg g−1, respectively, and the adsorption selectivity (αSTV/RA) reached 4.35. The adsorption isotherm and kinetic data of MOF-BA-1.0 for RA and STV obeyed the Langmuir isotherm model and pseudo second order kinetic model, respectively. The study demonstrated that MOF-BA-1.0 adsorbent could be used as a potential adsorbent to purify the active ingredients of stevia and obtain a high concentration of RA products.

Influences of trace graphite on the morphology and capacitance of CoOOH/Co(OH)2 nanocomposites

In this study, CoOOH/Co(OH)2 and CoOOH/Co(OH)2/graphite nanocomposites were obtained using a one-step microwave method. The morphologies of nanocomposites changed intensively by adding trace graphite, thereby affecting the electrochemical properties. The optimum capacitance of the electrode material can reach 402[Formula: see text]F[Formula: see text]g[Formula: see text] at 2[Formula: see text]A[Formula: see text]g[Formula: see text] and could be increased by 172% (692[Formula: see text]F[Formula: see text]g[Formula: see text] until 2200 cycles when the graphite content is 10[Formula: see text]mg. An excellent cycling stability of 86.2% capacitance retention of the highest value was attained after 10,000 cycles, which is higher than those of the CoOOH/Co(OH)2 electrode. The proposed provides a simple means to improve the electrochemical properties by changing the morphology of electrode material in supercapacitors.

One-step microwave synthesis CoOOH/Co(OH)2/CNT nanocomposite as superior electrode material for supercapacitors

CoOOH/Co(OH)2/CNT nanocomposite was rapidly prepared through one-step microwave method and characterised by XRD, SEM and XPS. Electrochemical performance was analysed via cyclic voltammetry, chronopotentiometry, cyclic charge-discharge and electrochemical impedance in a 6 M KOH electrolyte. The optimum capacitance of CoOOH/Co(OH)2/CNT can achieve 768 F g−1 at 2 A g−1 and could be further increased by 144% (1104 F g−1) after 700 cycles. An excellent cycling stability of 77.5% capacitance retention of the highest value (111% capacitance retention of the original value) was achieved after 3000 cycles. An asymmetric supercapacitor device on the basis of the CoOOH/Co(OH)2/CNT//AC showed the maximum energy density of 25 Wh kg−1 at a power density of 0.42 kW kg−1 and maintained 85% of the highest specific capacitance value after 20,000 cycles, thereby indicating its immense potential in energy storage devices.

Sensitive distance-based paper-based quantification of mercury ions using carbon nanodots and heating-based preconcentration.

This article reports the first fluorescent distance-based paper device coupled with an evaporating preconcentration system for determining trace mercury ions (Hg2+) in water. The fluorescent nitrogen-doped carbon dots (NCDs) were synthesized by a one-step microwave method using citric acid and ethylenediamine. The fluorescence turn-off of the NCDs in the presence of Hg2+ was visualized with a common black light, and the distance of the quenched fluorescence correlated to Hg2+ concentration. The optimal conditions for pH, NCD concentration, sample volume, and reaction time were investigated. Heating preconcentration was used to improve the detection limits of the fluorescent distance-based paper device by a factor of 100. Under the optimal conditions, the naked eye limit of detection (LOD) was 5 μg L−1 Hg2+. This LOD is sufficient for monitoring drinking water where the maximum allowable mercury level is 6 μg L−1 as established by the World Health Organization (WHO). The fluorescent distance-based paper device was successfully applied for Hg2+ quantification in water samples without interference from other cations. The proposed method provides several advantages over atomic absorption spectroscopy including ease of use, inexpensive material and fabrication, and portability. In addition, the devices are simple to fabricate and have a long shelf-life (>5 months).

One-step microwave synthesis of NiO/NiS@CNT nanocomposites for high-cycling-stability supercapacitors

NiO/NiS@CNT and NiO@CNT nanocomposites were rapidly fabricated using a one-step microwave method in 60 s. The electrochemical performances of the prepared electrodes with different mass ratios and microwave conditions for supercapacitors were investigated. NiO/NiS@CNT showed a high specific capacitance of 809.7 F g−1 at 1 A g−1 and tremendous cycling stability of approximately 100% retention after 20 000 cycles at 5 A g−1, indicating better electrochemical performance than NiO@CNT. The asymmetric supercapacitor device based on NiO/NiS@CNT//activated carbon (AC) displayed high energy and power density and excellent cycling stability, demonstrating enormous potential for energy-storage applications.

The three-dimensional flower-like Bi2WO6 assisted by ethanolamine through a microwave method for efficient photocatalytic activity.

The three-dimensional flower-like Bi2WO6 was synthesized through a one-step microwave method (the reaction temperature was 434 K and the reaction took 10 min) with the assistance of ethanolamine (EA). The prepared samples were characterized by X-ray diffraction, scanning electron microscopy, Fourier-transform infrared spectroscopy, ultraviolet–visible spectroscopy, PL, X-ray photoelectron spectroscopy and Brunauer–Emmett–Teller analysis. Methyl orange was used as target pollutant to evaluate the photocatalysis property of samples. Furthermore, the influence of the mechanism of EA on the structure and catalytic performance of Bi2WO6 was discussed. The detailed characterizations revealed that the three-dimensional flower-like Bi2WO6 was successfully synthesized with the assistance of EA. The results confirmed that EA significantly influenced the morphology of Bi2WO6 products. The addition of EA can effectively alter the pressure of the reaction and improve the crystal phase and structure of Bi2WO6 photocatalysts, enhancing the photocatalytic activity of samples and improving the photocatalytic efficiency. EA can serve as an assembling agent and structure-directing agent resulting in the formation of flower-like architectures. With the increase of the amount of EA, the as-prepared Bi2WO6 sample gradually forms a flower-like structure, leading to a shorter time of light holes migrating to the surface of the catalyst. It makes the compound rate significantly decreased, and improves the photocatalytic efficiency of the sample.

Microwave-assisted synthesis of nano petal-like α-Ni(OH)2/RGO and its electrochemical performance

A nanoscale petal-like α-Ni(OH)2/reduced graphene oxide (α-Ni(OH)2/RGO) composite was synthesized with the one-step microwave method. α-Ni(OH)2 particles with sizes of approximately 200 nm are uniformly distributed on the reduced graphene oxide sheet in the sample. When used as an electrode for alkaline rechargeable batteries, the discharge capacity of the α-Ni(OH)2/RGO composite reaches 333.5 mAh/g at 0.2C and 247.1 mAh/g at 10 C, respectively, with an excellent rate capability. After 2000 cycles, the capacity of the electrode is insignificantly attenuated, indicating a high capacity retention and cycling stability. The outstanding electrochemical properties are attributed to the nanoscale petal-like structure α-Ni(OH)2 anchoring on the RGO sheets, which facilitates ion diffusion and increases the active surface, which is effectively reacting with the electrolyte. The nanoscale petal-like electrode material fabricated in this study provides clues to address the problem of energy applications of high-performance alkaline rechargeable batteries.

Synthesis of Fluorescent Carbon Quantum Dots and Their Application in the Plant Cell Imaging

Carbon quantum dots (CQDs) exhibit tremendous advantages for plant growth study due to its strong fluorescence and good biocompatibility. The fluorescent CQDs were synthesized by the one-step microwave method with the raw materials of citric acid (CA) and urea (UR), and expressed a unique green fluorescence with the optimal excitation wavelength of over 400 nm through adjusting the doping of N elements. It is demonstrated that CQDs can act as deliver media in plant and fluorescent probes for plant cell imaging through directly cultivated in the seedlings of melon and wheat, respectively. Based on the effects of the fluorescent CQDs on plants growth, we can further study the mechanisms of the ions transport in plants.

Construction of magnetic-carbon-quantum-dots-probe-labeled apoferritin nanocages for bioimaging and targeted therapy.

Carbon dots (CDs) are one of the most highlighted carbon-based materials for biological applications, such as optical imaging nanoprobes, which are used for labeling cells in cancer treatment mainly due to their biocompatibility and unique optical properties. In this study, gadolinium (Gd)-complex-containing CDs were obtained through a one-step microwave method to develop multimodal nanoprobes integrating the advantages of optical and magnetic imaging. The obtained Gd-CDs exhibited highly fluorescent properties with excellent water solubility and biological compatibility. Natural apoferritin (AFn) nanocages, an excellent drug delivery carrier, are hollow in structure, with their pH-dependent, unfolding–refolding process at pH 2.0 and 7.4. The chemotherapeutic drug doxorubicin (DOX) can be highly effective and encapsulated into AFn cavity. A widely used tumor-targeting molecule, folic acid (FA), functionalized the surface of AFn to obtain an active tumor targeting effect on MCF-7 cells and malignant tumors in mice models. In this study, an AFn nanocarrier encapsulating high concentration of DOX labeled with magnetic and fluorescent Gd-CDs probe was developed. Gd-CDs exhibited a unique green photoluminescence and almost no toxicity compared with free GdCl3. Furthermore, Gd-doped CDs significantly increased the circulation time and decreased the toxicity of Gd3+ in in vitro and in vivo magnetic resonance imaging, which demonstrated that the AFn nanocages labeled with Gd-CD compounds could serve as an excellent T1 contrast agent for magnetic resonance imaging. The self-assembling multifunctional Gd-CDs/AFn (DOX)/FA nanoparticles have a great potential for cancer theranostic applications.

High-rate and long-life of Li-ion batteries using reduced graphene oxide/Co3O4 as anode materials

A new one-step microwave method was designed for synthesis of rGO/Co3O4, and the Li-ion battery showed high capacity and long life.

Photodegradation performance and recyclability of a porous nitrogen and carbon co-doped TiO2/activated carbon composite prepared by an extremely fast one-step microwave method

Porous (C,N)-TiO2/AC) composite bulk was prepared by a fast one-step microwave irradiation. It has very good photocatalytic properties and recyclability.

Electrodeposition of a carbon dots/chitosan composite produced by a simple in situ method and electrically controlled release of carbon dots.

Carbon dots (CDs), a new type of fluorescent nanomaterial, have drawn considerable attention due to their attractive applications in biolabeling, bioimaging and fluorescent probes. Here, a CDs/chitosan composite that can be straightforwardly used for further electrodeposition and electrically controlled release of CDs, was produced by a simple and novel in situ method based on a one-step microwave treatment of a chitosan solution. We choose the chitosan solution as the only reactant for producing the CDs/chitosan composite, because chitosan can not only serve as the precursor for preparing the CDs, but can also be frequently used for the electrodeposition. Importantly, the prepared CDs/chitosan composite is not only endowed with multicolor fluorescence features coming from the CDs, but also retains the pH-responsive film-forming properties of chitosan. On the basis of these favorable properties, we can straightforwardly employ the CDs/chitosan composite to construct fluorescent coatings, as well as a variety of multicolor fluorescent patterns on different electrodes or substrates through the electrodeposition technique. More interestingly, the release of CDs in the electrodeposited coatings or patterns can be controlled by electrical signals. Consequently, this CDs/chitosan composite with straightforward applications in electrodeposition and electrically controlled release of CDs is promising for use in photoluminescent coatings, fluorescent patterns, fluorescent labeling, and controlled release.

Rapid synthesis of a flower-like ZnO/rGO/Ag micro/nano-composite with enhanced photocatalytic performance by a one-step microwave method

Flower-like ZnO/rGO/Ag micro/nano-composites (MNCs) have been engineered by a one-step microwave technique using graphene oxide, AgNO3 and Zn(CH3COO)2 as raw materials without adding any external toxic reagent. This is a facile and rapid process requiring only low power microwave irradiation (120 W). Various characterization results showed that the flower-like ZnO/rGO/Ag MNCs consisted of a ZnO nanosheet and Ag nanoparticles and reduced graphene oxide (rGO) deposited on ZnO nanosheet surface. The composite shows an enhanced and faster ultraviolet and simulated daylight photocatalytic property, i.e. 92.73% and 70.43% degradation of methyl orange in 20 minutes as compared to the values of 70.91% and 60.82%, 55.48% and 50.61% by bare ZnO and rGO/ZnO, respectively. The enhanced photocatalytic property is attributed to an efficient charge transfer process from ZnO to both Ag and rGO. This method would be beneficial for synthesizing efficient ZnO-based ternary photocatalysts with a combination of metal and rGO.