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

Fe2V4O13 Nanoparticles Based Electrochemical Sensor for the Simultaneous Determination of Guanine and Adenine at Nanomolar Concentration

A simple strategy has been proposed for the simultaneous quantification of guanine (GU) and adenine (AD) using Fe2V4O13 nanoparticles (Fe2V4O13 NPs) modified carbon paste electrode (Fe2V4O13NPs/CPE) in phosphate buffer solution (PBS). The Fe2V4O13 NPs were prepared by a simple solution combustion method where sucrose was used as a fuel. The electrochemical behavior of GU and AD at the electrochemical interface has been studied by using cyclic voltammetry (CV) and differential pulse stripping voltammetry (DPSV). The results illustrate that the Fe2V4O13 NPs shows enhanced electrocatalytic activity and voltammetric response towards GU and AD. The proposed sensor showed linearity between the concentration 0.5 and 60 μM with limit of detection (LOD) 32 and 37 nM for GU and AD respectively. The sensitivity towards GU and AD were respectively found to be 1.393 and 1.851 μA/μM. Further, the proposed electrochemical sensor has been successfully employed to determine GU and AD contents in milk powder and calf thymus DNA samples

One-pot synthesis of Mn3O4/graphitic carbon nanoparticles for simultaneous nanomolar detection of Pb(II), Cd(II) and Hg(II)

In this paper, a facile one-step sucrose–nitrate decomposition method has been proposed to synthesis Mn3O4 nanoparticles (Mns)/graphitic carbon. The prepared material has been characterized by X-ray diffraction, Fourier transform infrared spectrometer, surface area analysis and transmission electron microscopy. The prepared Mns/graphitic carbon is drop-casted on glassy carbon electrode to allow the fabrication of electrochemical sensors for the simultaneous detection of Pb(II), Cd(II) and Hg(II) at nanomolar (nM) levels in aqueous solutions via differential pulse anodic stripping voltammetry. The proposed Mns/graphitic carbon sensors exhibit a wide linear range from 20 to 680 nM towards the simultaneous sensing of Cd(II), Pb(II) and Hg(II), and the corresponding limits of detection were found to be 0.48 × 10−11, 9.66 × 10−11 and 0.51 × 10−11 M, respectively. The practical application of the proposed sensor is evaluated within a real battery, industrial and chrome plating effluents

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

A versatile cost-effective and one step process to engineer ZnO superhydrophobic surfaces on Al substrate

Multifunctional superhydrophobic surfaces based on photocatalytic material, ZnO have generated significant research interest from both fundamental and potential applications. Superhydrophobic ZnO surfaces are usually made in multi steps by creating rough surface and subsequent hydrophobization by low-surface-energy materials. Herein, a simple and one step chemical bath deposition has been developed to prepare superhydrophobic ZnO surfaces on aluminum substrate. The aluminum surfaces covered with randomly distributed ZnO particles can not only present multiscale surface roughness, but also readily coordinate with fatty acid, leading to special wettability. The contact angle of the resulting superhydrophobic surface reaches up to 165 \ub1 2\ub0 and contact angle hysteresis of 4\ub0. The contact angle and contact angle hysteresis variation as a function of particle size has been discussed systematically based on surface morphology.Peer reviewed: YesNRC publication: Ye

Electrochemical synthesis of highly ordered polypyrrole on copper modified aluminium substrates

Fabrication of highly ordered conducting polymers on metal surfaces has received a significant interest owing to their potential applications in organic electronic devices. In this context, we have developed a simple method for the synthesis of highly ordered polypyrrole (PPy) on copper modified aluminium surfaces via electrochemical polymerization process. A series of characteristic peaks of PPy evidenced on the infrared spectra of these surfaces confirm the formation of PPy. The X-ray diffraction (XRD) pattern of PPy deposited on copper modified aluminium surfaces also confirmed the deposition of PPy as a sharp and intense peak at 2\u3b8 angle of 23\ub0 attributable to PPy is observed while this peak is absent on PPy deposited on as-received aluminium surfaces. An atomic model of the interface of PPy/Cu has been presented based on the inter-atomic distance of copper-copper of (1 0 0) plane and the inter-monomer distance of PPy, to describe the ordering of PPy on Cu modified Al surfaces.Peer reviewed: YesNRC publication: Ye

Stabilization of metastable tetragonal phase in a rhombohedral magnetoelectric multiferroic BiFeO3-PbTiO3

The phase formation behaviour of the magnetoelectric multiferroic 0.8BiFeO(3)-0.2PbTiO(3) was studied as a function of heat treatment at different temperatures of a sol-gel derived powder. While under ordinary synthesis conditions this composition exhibits antiferromagnetic ordering and a rhombohedral structure; the sol-gel-enabled low-temperature synthesis could stabilize a tetragonal metastable phase along with the stable rhombohedral phase, mimicking a morphotropic phase boundary state. The phase coexistence state exhibits relatively enhanced ferromagnetic correlation. The same system with a relatively higher PbTiO3 concentration, 0.65BiFeO(3)-0.35PbTiO(3), on the other hand, exhibits a rhombohedral metastable phase. These results suggest that the occurrence of metastable phases is a very common feature in the BiFeO3-PbTiO3 magnetoelectric ferroelectric system and that it affects the ferroelectric and magnetic properties of system quite remarkably