Pd nanoparticle-modified Bi2WO6 nanoplates used for visible-light-driven photocatalyst

Pd nanoparticles supported on Bi₂WO₆ nanoplates used for visible-light-driven photocatalyst were successfully synthesized by photoreduction deposition method under visible-light irradiation. Different analytical techniques including X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and photoluminescence spectroscopy revealed that face-centered cubic metallic Pd nanoparticles were uniformly loaded on top of orthorhombic Bi₂WO₆ nanoplates to form heterostructure Pd/Bi₂WO₆ nanocomposites. Photocatalytic activities of pure Bi₂WO₆ sample and heterostructure Pd/Bi₂WO₆ nanocomposites were studied through the photodegradation of rhodamine B (RhB) under visible-light irradiation. The photocatalytic efficiency of Bi₂WO₆ was increased to the highest by being loaded with 5 wt% Pd and then decreased by being loaded with 10 wt% Pd. The improved photocatalytic efficiency caused by high-efficiency diffusion and separation of photo-generated charge carriers was explained and can lead to superior photodegradation of RhB under visible-light irradiation.

     

Superparamagnetic and ferromagnetic behavior of ZnFe2O4 nanoparticles synthesized by microwave-assisted hydrothermal method

Zinc ferrite (ZnFe₂O₄) nanoparticles were successfully synthesized from Zn(NO₃)₂ · 6H₂O and Fe(NO₃)₃ · 9H₂O by microwave hydrothermal method at 150°C for 1 h. Cubic ZnFe₂O₄ with particle size below 7 nm was formed in the solution at pH ≥ 6. The crystallinity and particle size of ZnFe₂O₄ nanoparticles were increased after calcination. The effects of pH of the precursor solution and calcination on the particle size and crystallinity of the particles were studied. At room temperature the products show superparamagnetic and ferromagnetic properties, determined by their size. The formation mechanism of ZnFe₂O₄ was also discussed according to the experimental results.

     

Hydrothermal synthesis of hexagonal WO3 nanowires with high aspect ratio and their electrochemical properties for lithium-ion batteries

One dimensional WO₃ nanowires with high aspect ratio of >200 were synthesized by hydrothermal method. The effects of reaction temperature and time on phase and morphologies were studied and discussed. In this research, a suitable hydrothermal condition is at 200°C for 48 h. XRD, SEM, and TEM results show that the product is hexagonal WO₃ phase with diameter of 25 nm and several ten micrometers long with growth in the c direction. The electrochemical properties were tested for rechargeable lithium batteries. The WO₃ NWs electrode exhibits a stability trend over the 30 cycle testing. Some long-term activation process is attributed to the WO₃ NWs electrode during charge/discharge reaction.

     

Characterization of MeWO4 (Me = Ba, Sr and Ca) nanocrystallines prepared by sonochemical method

Metal tungstates (MeWO₄, Me = Ba, Sr and Ca) were successfully prepared using the corresponding Me(NO₃)₂·2H₂O and Na₂WO₄·2H₂O in ethylene glycol by the 5 h sonochemical process. The tungstate phases with scheelite structure were detected with X-ray diffraction (XRD) and selected area electron diffraction (SAED). Their calculated lattice parameters are in accord with those of the JCPDS cards. Transmission electron microscopy (TEM) revealed the presence of nanoparticles composing the products. Their average sizes are 42.0 ± 10.4, 18.5 ± 5.1 and 13.1 ± 3.3 nm for Me = Ba, Sr and Ca, respectively. Interplanar spaces of the crystals were also characterized with high-resolution TEM (HRTEM). Their crystallographic planes are aligned in systematic array. Six different vibration wavenumbers were detected using Raman spectrometer and are specified as ν₁(A_g), ν₃(B_g), ν₃(E_g), ν₄(B_g), ν₂(A_g) and free rotation. Fourier transform infrared (FTIR) spectra provided the evidence of scheelite structure with W-O anti-symmetric stretching vibration of [WO₄]²⁻ tetrahedrons at 786-883 cm⁻¹. Photoluminescence emission of the products was detected over the range of 384-416 nm.     

Degradation of rhodamine B photocatalyzed by Eu-doped CdS nanowires illuminated by visible radiation

CdS nanowires doped with different contents of Eu dopant were synthesized by solvothermal method. XRD, SEM, TEM and Raman analyses certified that the as-synthesized samples were hexagonal CdS uniform nanowires. The pure CdS nanowires were 1–3 ?μm long and 80 ?nm diameter with the 1st and 2nd order longitudinal phonon modes at 298 and 594 ?cm^?1. The 3% Eu-doped CdS wires were 800 ?nm–2.5 ?μm long and 75 ?nm diameter with the 1st and 2nd order longitudinal phonon modes at 296 and 593 ?cm^?1. CdS nanowires grew along the [001] direction due to the surface energy effect. The photocatalytic properties of CdS and Eu-doped CdS nanowires were investigated for the degradation of rhodamine B (RhB) illuminated by visible radiation. In this research, Eu dopant played the role in promoting the photocatalytic kinetics because Eu³⁺ ions act as an electron acceptor to promote charge separation and photocatalytic activity. Both ^●OH and ^●O₂^? were the main active radicals used to transform RhB molecules into CO₂, H₂O and other intermediates.     

Influence of pH on the synthesis ZnO nanorods and photocatalytic hydrogen production from glycerol solution

Photocatalytic oxidation of glycerol at ambient conditions has been investigated with the use of Zinc oxide photocatalysts. Zinc oxide nanorods were prepared via a simple hydrothermal method using zinc nitrate and sodium hydroxide in the solution pH of 7, 8 and 9. The samples prepared in this way were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), Brunauer-Emmett-Teller (BET) and ultraviolet–visible spectroscopy (UV–vis). The pH of the solution is 7, the sample contains zinc hydroxide nitrate hydrated. When the pH of solution was adjusted to 8 and 9, the samples consisted of pure hexagonal wurtzite ZnO without impurity detection. The influence of solution pH on hydrogen formation was investigated. The wurtzite ZnO nanorods synthesized in a solution with pH 9 are considered promising photocatalysts for hydrogen production under xenon radiation.     

BiOX (X = Cl,Br, and I) Nanoplates Prepared by Surfactant-Free Microwave Synthesis and Their Photocatalytic Performance

Russian Journal of Physical Chemistry A - Bismuth oxyhalide (BiOX; X = Cl, Br, and I) nanoplates were successfully synthesized by microwave irradiation of surfactant-free aqueous solutions. X-rays...     

Visible-light-driven photocatalysis of heterostructure Ag/Bi<Subscript>2</Subscript>WO<Subscript>6</Subscript> nanocomposites and their photocatalytic degradation of dye under visible light irradiation

Ag/Bi₂WO₆ nanocomposites were successfully synthesized by a combination of hydrothermal method and ultrasonic vibration. The phases, vibration modes, constituents and morphologies were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. The visible-light-driven photocatalytic activitiy of 0–10 wt% Ag/Bi₂WO₆ samples was studied by determining the photodegradation of rhodamine B under xenon lamp. In this research, 10 wt% Ag/Bi₂WO₆ nanocomposites exhibit the highest efficiency and have the promising photocatalytic properties for waste water treatment.     

Photocatalytic activity of ZNO with different morphologies synthesized by a sonochemical method

Different morphologies of ZnO structures were successfully synthesized in precursor solutions with the pH of 8, 9, 10, 11, and 12 by a sonochemical method at room temperature. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier Transform Infrared (FTIR) and Raman spectroscopy. The photocatalytic activities of ZnO samples with different morphologies were evaluated via the degradation of methylene blue (C₁₆H₁₈ClN₃S). In this research, the flower-like ZnO sample of densely assembled nanoplates exhibited the highest photodegradation of 64% under UV light irradiation within 300 min.     

Ag<Subscript>3</Subscript>PO<Subscript>4</Subscript>/Bi<Subscript>2</Subscript>MoO<Subscript>6</Subscript> heterostructures with enhanced visible light photocatalytic activity for the degradation of rhodamine B

Highly efficient visible-light-driven Ag₃PO₄/Bi₂MoO₆ hybrid photocatalysts with different mole ratios of Ag₃PO₄ were prepared via sonochemical method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that product are cubic Ag₃PO₄ nanoparticles supported on orthorhombic Bi₂MoO₆ nanoplates. Under visible light irradiation (>420 nm), the Ag₃PO₄/Bi₂MoO₆ photocatalysts displayed the higher photocatalytic activity than pure Bi₂MoO₆ for the decolorization of rhodamine B (RhB). Among the hybrid photocatalysts, 10% Ag₃PO₄/Bi₂MoO₆ exhibited the highest photocatalytic activity for the decolorization of RhB due to the efficient separation of electron–hole pairs.