Insertion study of alkali metal cations into layered vanadium oxide foam

The reaction of inorg. ions (Li+, Na+, and K+) with the lamellar material of compn. (V2O5)​(C16H33NH2)​1.3 under reflux conditions in alc.-​water mixed medium results in the rapid and quant. displacement of the surfactant to form inorg. ions intercalated vanadium oxides. The products were characterized by employing powder X-​ray diffraction (PXRD)​, Fourier transform IR (FTIR)​, thermogravimetric​/DTA (TG​/DTA)​, and SEM (SEM)​. FTIR and thermal studies showed the displacement of surfactants by inorg. ions during ion-​exchange process. The XRD peaks obsd. at lower and wider 2θ angles reflect the interlayer sepn. and crystallinity of the host vanadium oxide framework

alpha-MoO3 nanoparticles: solution combustion synthesis, photocatalytic and electrochemical properties

Nanoparticles of ultra-porous MoO3 were synthesized in a single step by a solution combustion reaction using molybdenum metal powder as precursor for the first time. The effects of the preparation conditions, such as the temperature and precursor concentration, on the crystalline phase and morphology of the products were studied systematically. The analytical techniques SEM, TEM, PXRD, TGA, FTIR, and SAED were used to characterize the morphology, composition, and structure of the as-prepared products. The TEM images of MoO3 show the sizes of the particles to be in the range of 2-10 nm. Electrochemical characterization of MoO3 was carried out in 0.5 M H2SO4. The specific capacitance and electrochromic properties of MoO3 were studied. The high photocatalytic activity of MoO3 was investigated using methylene blue azo dye at various concentrations. MoO3 showed the ability to degrade 100% of methylene blue present at high concentrations of about 75 mg L-1

Morphological Evolution of (NH4)0.5V2O5·mH2O Fibers into Belts, Triangles, and Rings

In this contribution, single-crystalline (NH4)0.5V2O5·mH2O xerogels made of belts, rings, triangles, and ovals have been synthesized using a surfactant-free hydrothermal method. The analytical techniques of scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared (FTIR), high-resolution TEM (HRTEM), and selected area electron diffraction (SAED) have been used to characterize the morphology, composition, and structure of the as-prepared products. On the basis of SEM and TEM observations, we suggested that the as-prepared (NH4)0.5V2O5·mH2O rings, triangles, and ovals have been formed by connecting two ends of the vanadium oxide sheet made of edge and corner sharing VO5 square pyramids. The as-prepared (NH4)0.5V2O5·mH2O nanobelts are up to several hundreds of micrometers long, 402–551 nm wide, and 235–305 nm thick. The thickness and width of the rings are respectively 454 nm and 1 μm. Triangles with three unequal sides having a thickness of 143 nm and a width of 1 μm were also formed. The crystalline orthorhombic phase of shcherbianite V2O5 was obtained on calcination of (NH4)0.5V2O5·mH2O at 350 °C for 2 h. The SEM image of this V2O5 product retains the parent morphology of the preheated compound. A possible reaction mechanism and the growth process involved in the formation of belts/rings/triangles and ovallike microstructures are discussed

Synthesis and characterization of microstructural α-​Mn2O3 materials

Low-​dimensional α-​Mn2O3 materials with novel surface morphologies were prepd. by thermal decompn. of hydrothermal-​derived MnCO3. The powder x-​ray diffraction pattern reveals that the Mn2O3 microstructures are of cubic phase structure. From FTIR results, the peaks ≈600-​450 cm-​1 correspond to Mn-​O bending vibrations. From the TGA results, the obsd. major wt. loss ≈31​% between 350 and 540° is due to the decompn. of MnCO3 into Mn2O3. The XPS results showed that Mn is in +3 oxidn. state. The peaks at 641.2 and 652.73 eV are assigned to the Mn2p3​/2 and Mn2p1​/2 of Mn3+ states, resp. The SEM images showed that the α-​Mn2O3 products exhibit spheres, dumbbell-​, and peanut-​shaped microstructure. These microstructures are mainly composed of wires​/rods and particles. The SEM results also revealed that the obtained α-​Mn2O3 maintains the frame structure of the precursor MnCO3

Nickel tungstate nanoparticles: synthesis, characterization and electrochemical sensing of mercury(II) ions

Abstract Nano particulate metal oxides gained significant research interest in recent years for various applications with the intension of exploring enhanced properties of miniaturization. In this research work, nickel tungstate nanoparticles (NiWO4 nanoparticles) were successfully synthesized via a simple and efficient sucrose-nitrate decomposition method. The synthesized nanoparticles were characterized using various analytical techniques such as PXRD, SEM, TEM, BET measurements and FTIR. Transmission electron microscope images reveals the nearly spherical shaped nanoparticles of average particle size 15–35 nm. Photoluminescence characteristics of synthesized NiWO4 nanoparticles were investigated at room temperature. Further, the prepared nanoparticles were utilized as glassy carbon electrode modifier for trace level electrochemical sensing of toxic mercury present in water samples. The electrochemical behavior of mercury(II) ions at modified electrode interface has been studied by cyclic voltammetry (CV) and differential pulse stripping voltammetry (DPSV). The results illustrate that, the proposed modified GCE sensor exhibits linearity between the concentration range 10–600 nM with the limit of detection 2.25 nM based on 3σ method for mercury(II) ions