Simple One-step Hydrothermal Synthesis Research Articles

2D MoSe2-Ni(OH)2 nanohybrid as an efficient electrode material with high rate capability for asymmetric supercapacitor applications

Ni(OH)2 is recognized as a good electrode material for supercapacitors, but it suffers from capacitance decrease with repeated cycles at high current density. To enhance its electrochemical performance even at high current density, a newer two dimensional molybdenum diselenide – nickel hydroxide nanohybrid (2D MoSe2-Ni(OH)2) have been prepared by a simple one-step hydrothermal synthesis. The 2D MoSe2-Ni(OH)2 nanohybrid have an excellent electrochemical properties due to their synergistic effect. This 2D-2D hybrid electrode exhibits a higher specific capacitance of 1175 F g−1 than Ni(OH)2 nanosheets (933 F g−1) at 1 A g−1 and also maintains a high rate capability of 85.6% at 10 A g−1. In addition, the 2D MoSe2-Ni(OH)2 nanohybrid based asymmetric supercapacitor (ASC) is fabricated and provides a high energy density of 43 Wh kg−1, high power density of 8181 W kg−1 with the capacitance retention of 85% even after 5000 cycles at a high current density of 1 A g−1. When two ASC devices are assembled in series and then charged for 1 min, gives power to light-emitting-diode for more than 3 min suggesting the great significant of the prepared 2D MoSe2-Ni(OH)2 nanohybrid for excellent energy storage.

One step synthesis of rGO-Ni3S2 nano-cubes composite for high-performance supercapacitor electrodes

In the last decade, supercapacitors possessing high power density and cyclic stability have attracted great interests in various applications. Graphene-based composite electrodes are known as a promising candidate for supercapacitors due to synergistic effects. For the first time, in this work, we develop a simple one-step hydrothermal synthesis of graphene wrapped Ni3S2 nanocubes (rGO-Ni3S2) composite for high-performance and low-cost supercapacitor electrodes. The rGO-Ni3S2 electrode exhibits an ultrahigh specific capacity of 616 C g−1 at the current density of 1 A g−1 with excellent cycling durability of 92.7% after 5000 cycles, which is much better when compared with the counterpart without graphene (pure Ni3S2). We attribute the remarkable performance of the rGO-Ni3S2 electrode to the synergistic effects of the graphene as the conductive support and Ni3S2 cubics as the pseudocapacitive material. This work constitutes a step forward towards the development of low-cost and high-performance supercapacitors for the next generation of portable electronics.

Bioinspired Antimicrobial Nanodots with Amphiphilic and Zwitterionic-like Characteristics for Combating Multidrug-Resistant Bacteria and Biofilm Removal

Inspired by the natural antimicrobial peptides, we have developed a benign antimicrobial nanodot (BAM dot) via a simple one-step hydrothermal synthesis. The BAM dot possesses the unique properties of both nanoparticles and biomaterials, leading to excellent antibacterial properties with a high therapeutic index. Specifically, this BAM dot has ultrasmall size (3.83 ± 0.73 nm) with a charged neutral surface. They also exhibited amphiphilic and zwitterionic-like properties, which enabled effective bacteria membrane permeabilization, leading to a rapid bactericidal effect and significant biofilm removal. This study opens up new opportunities to design effective bioinspired nanomaterials for combating superbugs against drug resistance and their related applications.

Rapid Photocatalytic Decolorization of Methyl Orange under Visible Light Using VS4/Carbon Powder Nanocomposites

Photocatalytic decolorization of the dye compounds represents a promising approach for textile wastewater treatment, and thus, development of new photocatalysts will be of strong interest. Herein, a novel photocatalyst based on transition metal chalcogenides vanadium tetrasulfide (VS4) was prepared via a simple one-step hydrothermal synthesis, and the synthesized VS4/carbon powder nanocomposites exhibited excellent photocatalytic decolorization efficiency under visible light irradiation. A significantly high methyl orange (MO) decolorization rate of 13.4–19.8 mg L–1 h–1 was achieved. Reactive species such as •O2–, h+, and e– generated through this photocatalytic process have played key roles in decolorization with phthalic acid as a product. The optimal catalyst dosage was determined to be 1.0 g L–1. The decolorization rate was enhanced with the increase in initial MO concentration, and an acidic condition favored the degradation. The VS4/carbon powder nanocomposites could maintain the MO decolorization e...

Glycerol-Modified Binary Layered Double Hydroxide Nanocomposites for Uranium Immobilization via Extended X-ray Absorption Fine Structure Technique and Density Functional Theory Calculation

Novel, efficient, glycerol-modified nanoscale layered double hydroxides (rods Ca/Al LDH-Gl and flocculent Ni/Al LDH-Gl) were successfully synthesized by a simple one-step hydrothermal synthesis route and showed excellent adsorption capacities for U(VI) from aqueous solutions under various environmental conditions. The advanced spectroscopy analysis confirmed the existence of abundant oxygen-containing functional groups (e.g., C–O, O–C═O, and C═O) on the surfaces of Ca/Al LDH-Gl and Ni/Al LDH-Gl, which could provide enough free active sites for the binding of U(VI). The maximum adsorption capacities of U(VI) calculated from the Sips model were 266.5 mg·g–1 for Ca/Al LDH-Gl and 142.3 mg·g–1 for Ni/Al LDH-Gl at 298.15 K, and the higher adsorption capacity of Ca/Al LDH-Gl might be due to more functional groups and abundant high-activity “Ca–O” groups. Macroscopic experiments proved that the interaction of U(VI) on Ca/Al LDH-Gl and Ni/Al LDH-Gl was due to surface complexation and electrostatic interactions. Th...

One-pot synthesis of a ceria-graphene oxide composite for the efficient removal of arsenic species.

Arsenic contamination has posed a health risk to millions of people around the world. In this study, we describe a simple and facile one-step hydrothermal synthesis of a ceria-graphene oxide (ceria-GO) composite for the efficient removal of arsenic species. The prepared ceria-GO composite materials exhibited almost complete (over 99.99%) and quick removal of both arsenic species within 0.1 mg L-1 of the initial concentration. The calculated adsorption capacities were 185 mg g-1 for As(iii) and 212 mg g-1 for As(v). It was found that Ce3+ is an active site and continuously adsorbs arsenic species; there is a concomitant change from Ce4+ to Ce3+ due to the solution redox environment. This increase in the Ce3+ concentration further facilitates the complete removal of arsenic species in solution. Thus our approach offers a promising potential for the treatment of arsenic-contaminated drinking water.

A simple one-step hydrothermal synthesis and photocatalysis of bowl-like BaTiO3 nanoparticles

ABSTRACTBowl-like BaTiO3 nanoparticles were synthesized via a simple one-step hydrothermal synthesis process. The morphology and structure of the synthesized bowl-like structures were characterized by X-ray diffraction, scanning electron microscope, transmission electron microscope, and Fourier transform infrared spectroscopy. The results show that the typical diameter of bowl-like BaTiO3 is 100 nm, which presented cubic structure formed by a self-assembly nanocrystals with diameter of 31 nm. In addition, the obtained BaTiO3 nanoparticles were used as catalysts to photodegrade rhodamine B.

Use of manganese dioxide as oxidant in polymerization of aniline on carbon black for supercapacitor performance

α-Manganese dioxide (MnO2) and β-MnO2 have been prepared by a simple one-step hydrothermal synthesis method. Polyaniline (PANI)/carbon black composites were synthesized in acidic medium by an in situ polymerization method using α-MnO2, β-MnO2, and ammonium peroxydisulfate (APS) as chemical oxidant. The morphology, structure, and electrochemical performances are characterized by X-ray diffraction spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, cyclic voltammetry, charge–discharge test, and electrochemical impedance measurements. The PANI/carbon black composite (PANI/C-2) prepared using β-MnO2 as oxidant shows significantly better specific capacity performance compared with those prepared using α-MnO2 and APS as oxidant. Addition of carbon black into the PANI composites prepared via the conventional polymerization method showed improved specific capacitance.

Large area synthesis of well-dispersed β-MnO2 nanorods and their electrochemical supercapacitive performances

Highly dispersed β-MnO2 nanorods are prepared by a simple one-step hydrothermal synthesis method. The structure and morphology of the β-MnO2 nanorods are investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The supercapacitive performances for the electrode made of β-MnO2 nanorods are investigated by cyclic voltammetry (CV) and galvanostatic charging-discharging (GCD). The SEM and TEM results show that these β-MnO2 nanorods have homogeneous 1-D nanostructures in diameter of about 55nm and length of about 500nm. When evaluated for supercapacitor electrode, a relatively high specific capacitance of 247.2 F/g is obtained at current density of 1 A/g in 1mol/L KOH aqueous solution. And desirable rate performance and good cycling stability are also demonstrated for the well-dispersed β-MnO2 nanorods.

Electrochemical Reduction CO2 to Formate on Cuxo Electrode

In recent years, CO2 conversion using electrochemical catalysis approaches has attracted great attention due to its several advantages such as the controllable electrode potentials, reaction temperature and the recycled supporting electrolytes1. But the low performance of the electrocatalysts (i.e., low catalytic activity and insufficient stability) hinders its practical application1. Cu have been explored to catalyze CO2 electroreduction due to its low cost, abundant reserve and reasonable overall Faradaic efficiency towards fuel production(e.g. CO, CH4, C2H4, formate, alcohols)2. However, the energetic efficiency of Cu is limited by the large overpotential (>0.7 V) required for CO2 reduction to outcompete H2O reduction3. Furthermore, Cu electrode rapidly lose their CO2 reduction activity2. Achieving efficient Cu-catalyzed CO2 reduction requires preparing Cu particles whose surfaces have active sites that are different from those on the surface of a metallic Cu electrode4. Here, we prepared CuxO particles by a simple one-step hydrothermal synthesis, and applied them to the gas diffusion electrode, these electrodes exhibited good electrochemical performance of high catalytic activity and high selectivity. The CuxO were prepared using a simple hydrothermal method as follows: 0.04 mol Cupric Acetate Monohydrate and 0.02mol hexamethylenetetramine were mixed under stirring to form a homogeneous solution. Then the mixture was transferred into a 100 mL stainless-steel autoclave and heated at 180℃ for 2 h. Then the precipitate was collected by centrifugation, washed with deionized water and absolute ethanol for several times, until the pH was neutral, finally dried at oven at 85℃ for 12h. The crystal structure of the product was characterized by XRD and SEM. The catalyst electrode was prepared by CuXO powder bonded with Nafion solution and isopropanol, and spread over the gas diffusion layer (GDL). The catalytic activity of CuXO nanocatlyst supported on GDL as the cathode electrode was measured using cyclic voltammetry (CV) and linear sweep voltammetry (LSV) in 0.5M KHCO3 aqueous solution saturated with both N2 and CO2, respectively. Figure 1 shows the CV curves on the CuxO/GDL electrode. It can be seen that the anodic peaks between 0V~ 0.85V and the cathodic peak between -0.6V~ 0.25V. The onset potential in 0.5M KHCO3 solution saturated with CO2 was found to be at 0.20 V, which is 250 mV more positive than that under N2 ( 0 V). At an potential of -1.25V, the current density in CO2-saturated 0.5M KHCO3 reached 17.1 mAcm-2 (Fig. 1). All the above reults indicates that participation of CO2 reduction contributes to the enhancement of cathodic current.

Electrochemical Reduction CO2 to Formate on Sno/Gdl Electrode

The CO2 conversion using electrochemical method is an attractive proposition due to its several advantages such as the controllable electrode potentials, reaction temperature and the recycled supporting electrolytes.1 To date, formic acid, carbon monoxide, methanol, and oxalic acid have been prepared by this way. However, the key technological challenge for electrochemical reduction of CO2is the preparation of the electrode with high catalytic activity, high selectivity and long term stability. Considering these difficulties, developing new material synthesis technology to give innovative new catalysts with optimal performance is the priority. Tin (Sn) and copper (Cu) are considered as promising electrocatalysts to convert carbon dioxide (CO2) to fuels (e.g. formate, methanol or hydrocarbons) because of their low cost, easy availability and reasonable overall Faradaic efficiency towards fuel production.2 However, the deactivation of Sn metal electrodes during CO2 reduction is very fast, and requires at least 0.86 V of overpotential to attain a CO2 reduction partial current density of 4−5 mAcm-2 in an aqueous solution saturated with 1 atm CO2.3 Combined with the advantages of metal tin, we here report a simple one-step hydrothermal synthesis of SnO nanocatalyst with good electrochemical performance of high catalytic activity and high selectivity. The crystalline SnO nanocatalyst were prepared using a simple hydrothermal method as follows: 2 mmol Tin (Ⅱ) Chloride dehydrates, 12 mmol carbamide and 0.2g PVP were dissolved into 50mL deionized water under vigorous stirring to form a homogeneous solution. Then the mixture was transferred into a 100 mL stainless-steel autoclave and heated at 140,160,180,200 oC for 12 h, respectively. Then the precipitate was collected by centrifugation, washed with deionized water and absolute ethanol for several times, until the pH was neutral, finally dried at oven at 85oC for 12h. The crystal structure of the product was characterized by XRD and SEM. The catalyst electrode was prepared by SnO powder bonded with Nafion solution and isopropanol, and spread over the gas diffusion layer (GDL). The catalytic activity of SnO nanocatlyst supported on GDL as the cathode electrode was measured using cyclic voltammetry (CV) and linear sweep voltammetry (LSV) in 0.5M KHCO3 aqueous solution saturated with both N2 and CO2, respectively. Figure 1 shows the CV curves on the SnO/GDL electrode. It can be seen that the anodic peaks between -0.75V~ -0.25V and the cathodic peak between -0.55V~ -0.9V. The onset potential in 0.5M KHCO3 solution saturated with CO2 was found to be at -0.554 V, which is 12 mV more positive than that under N2 (-0.673V). At an potential of -1.6V, the current density in CO2-saturated 0.5M KHCO3 reached 17.1 mAcm-2 which is nearly 4 times higher than that under N2 (Fig. 1). All the above reults indicates that participation of CO2 reduction contributes to the enhancement of cathodic current.

Fluorescent carbon dots for auramine O determination and logic gate operation

Carbon dots (CDs) with a fluorescence quantum yield of approximately 2.41% were prepared by simple one-step hydro-thermal synthesis of triethylenetetramine-N, N, N′, N″, N‴, N‴-hexaacetic acid (TTHA). The obtained CDs possess excitation wavelength-dependent and pH insensitive photoluminescence (PL) properties. Notably, the as-prepared CDs also exhibited unique auramine O (AO)-stimulus-responsive dual-emission fluorescence individuality, with which detection of AO using CDs has been performed through a fluorescence resonance energy transfer process. The fluorescence signals are linearly correlated with the concentration of AO over a range of 0.18–16.0μM (R2=0.9989), with a limit of detection (3σ) of 54nM. Additionally, a keypad lock and a NOR–AND logic gate was designed as well.

MnO2 nanosilks self-assembled micropowders: Facile one-step hydrothermal synthesis and their application as supercapacitor electrodes

Novel MnO2 nanosilks self-assembled micropowders have been prepared by a simple one-step hydrothermal synthesis method. The structure and morphology of the MnO2 are investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The capacitive properties of the MnO2 are investigated by cyclic voltammetry (CV) and constant current charge–discharge. The SEM results showed that the MnO2 micropowders are assembled by numerous one-dimensional MnO2 nanosilks. These MnO2 nanosilks are found to be 30–50nm in diameter and characteristic length up to 2μm. When evaluated for supercapacitor electrode, a desirable specific capacitance of 135F/g for the single MnO2 electrode is obtained at current density of 0.15A/g in 1M Na2SO4 aqueous solution.

Facile preparation of Ag2S nanoparticles with broad photoelectric response region

In this paper, Ag2S nanoparticles (NPs) are prepared by a simple one-step hydrothermal synthesis. Various particle diameters of Ag2S NPs are obtained under different concentrations of surfactants. A mechanism for the nucleation and growth of Ag2S NPs under the influence of surfactants is proposed. X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and UV–vis absorption spectroscopy are used to characterize the obtained product. In order to investigate the photoelectric properties of the Ag2S NPs, surface photovoltage (SPV) technique was studied. The Ag2S NPs perform intense photoelectric response in the range of NIR and visible region, which could be applied in photoelectric detector.