Synthesis and Characterization of CeO2 Nanoparticles via Solution Combustion Method for Photocatalytic and Antibacterial Activity Studies

CeO₂ nanoparticles have been proven to be competent photocatalysts for environmental applications because of their strong redox ability, nontoxicity, long-term stability, and low cost. We have synthesized CeO₂ nanoparticles via solution combustion method using ceric ammonium nitrate as an oxidizer and ethylenediaminetetraacetic acid (EDTA) as fuel at 450 °C. These nanoparticles exhibit good photocatalytic degradation and antibacterial activity. The obtained product was characterized by various techniques. X-ray diffraction data confirms a cerianite structure: a cubic phase CeO₂ having crystallite size of 35 nm. The infrared spectrum shows a strong band below 700 cm⁻¹ due to the Ce−O−Ce stretching vibrations. The UV/Vis spectrum shows maximum absorption at 302 nm. The photoluminescence spectrum shows characteristic peaks of CeO₂ nanoparticles. Scanning electron microscopy (SEM) images clearly show the presence of a porous network with a lot of voids. From transmission electron microscopy (TEM) images, it is clear that the particles are almost spherical, and the average size of the nanoparticles is found to be 42 nm. CeO₂ nanoparticles exhibit photocatalytic activity against trypan blue at pH 10 in UV light, and the reaction follows pseudo first-order kinetics. Finally, CeO₂ nanoparticles also reduce Cr^VI to Cr^III and show antibacterial activity against Pseudomonas aeruginosa.     

Ag Doped Titanium Dioxide Nanocomposite‐modified Glassy Carbon Electrode as Electrochemical Interface for Catechol Sensing

The electrochemical sensing of catechol (CC) on a glassy carbon electrode modified with the ionothermal assisted synthesis of Ag doped TiO₂ a nanoparticle has been successfully demonstrated for the first time.Ag doped TiO₂ nanoparticles composite modified glassy carbon electrode exhibits higher electrocatalytic activity towards oxidation of catechol than glassy carbon electrode itself. The modified electrode also exhibits high selectivity towards this analyte in the presence of some of the metal ions and some of the biological compounds. Linear ranges and the limit of detections with the above electrode are 1–15 µM and 0.0249 µM respectively. The optimized protocol has been utilized for monitoring the catechol in some of the natural samples like apple juice and green tea and in industrial effluents.     

Interactions of Environmental Pollutant Aromatic Amines With Photo Excited States of Thiophene Substituted 1,3,4-Oxadiazole Derivative: Fluorescence Quenching Studies

Journal of Fluorescence - In the present work, the fluorescence quenching of novel thiophene substituted1,3,4-oxadiazole derivative 2-(4-(4-vinylphenyl)...     

Microwave-assisted functionalization of glassy carbon spheres: electrochemical and mechanistic studies

Functionalization of glassy carbon spheres have been carried out by microwave irradiation in the presence of modifier molecules through oxidation followed by amidation reaction. The glassy carbon spheres were initially catalyzed by treating with concentrated nitric acid to introduce surface-bound carboxylic groups, and its subsequent amidation reaction in the presence of p-nitroaniline yields p-nitroanilide-functionalized substrate materials. These derivatized glassy carbon spheres have been electrochemically characterized by immobilizing them on bppg electrode and studying its voltammetric behavior. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy studies have revealed that the modifying molecules are surface bound and covalently attached on the carbon substrate.     

Multiscale charge injection and transport properties in self-assembled monolayers of biphenyl thiols with varying torsion angles

This article describes the molecular structure-function relationship for a series of biphenylthiol derivatives with varying torsional degree of freedom in their molecular backbone when self-assembled on gold electrodes. These biphenylthiol molecules chemisorbed on Au exhibit different tilt angles with respect to the surface normal and different packing densities. The charge transport through the biphenylthiol self-assembled monolayers (SAMs) showed a characteristic decay trend with the effective monolayer thickness. Based on parallel pathways model the tunneling decay factor β was estimated to be 0.27??(-1) . The hole mobility of poly(3-hexylthiophene)-based thin-film transistors incorporating a biphenylthiol SAM coating the Au source and drain electrodes revealed a dependence on the injection barrier with the highest occupied molecular orbital (HOMO) level of the semiconductor. The possible role of the resistivity of the SAMs on transistor electrodes on the threshold voltage shift is discussed. The control over the chemical structure, electronic properties, and packing order of the SAMs provides a versatile platform to regulate the charge injection in organic electronic devices.     

Mesoporous Foam TiO2 Nanomaterials for Effective Hydrogen Production

Hydrolysis of TiCl₄ in a diether‐functionalized imidazolium ionic liquid (IL), namely 1‐methyl‐3‐[2‐(2‐methoxy(ethoxy)ethyl]imidazolium methane sulfonate (M(MEE)I ? CH₃SO₃), results in a heterostructured organic/inorganic and sponge‐like porous TiO₂ material. The thermal treatment (300 °C) followed by calcination (500 °C) affords highly porous TiO₂. The characterization of the obtained samples (with and without IL, before and after calcination) by XRD, SEM, and TEM reveals TiO₂ anatase crystalline phases and irregular‐shaped particles with different porous structures. These hierarchical‐structured mesoporous TiO₂ nanomaterials were employed as efficient photocatalysts in the water‐splitting process, yielding up to 1304 μmol g^?1 on hydrogen production.     

Design, synthesis and X-ray structure of protein-ligand complexes: important insight into selectivity of memapsin 2 (beta-secretase) inhibitors

Structure-based design, synthesis, and X-ray structure of protein-ligand complexes of memapsin 2 are described. The inhibitors are designed specifically to interact with S2- and S3-active site residues to provide selectivity over memapsin 1 and cathepsin D. Inhibitor 6 has exhibited exceedingly potent inhibitory activity against memapsin 2 and selectivity over memapsin 1 (>3800-fold) and cathepsin D (>2500-fold). A protein-ligand crystal structure revealed cooperative interactions in the S2- and S3-active sites of memapsin 2. These interactions may serve as an important guide to design selectivity over memapsin 1 and cathepsin D.     

Derivatization and characterization of functionalized carbon powder via diazonium salt reduction

Chemical reduction of 4-chloro-2-nitrobenzenediazonium chloride salt in the presence of hypophosphorous acid and carbon powder results in functionalized carbon powder with chloronitrophenyl groups attached on carbon particle surface. This type of bulk derivatization protocol is very useful and most inexpensive compared to widely used electrochemically assisted derivatization protocol. The derivatized carbon powder has been characterized by studying its Fourier transform infrared spectroscopy (FTIR) and cyclic voltammetric studies. The surface functionalized moieties have been examined electrochemically by immobilizing them onto the surface of basal plane pyrolytic graphite electrode and studying its cyclic voltammetry. The effect of pH, scan rate (v), and the peak potentials (E _p) as a function of pH has revealed that the species are surface bound in nature and covalently attached on the carbon surface. The FTIR studies of the derivatized carbon powder have revealed that the modifying molecule is covalently attached on the carbon particle surface.     

Surface plasmon resonance effect of Ag metallized SnO2 particles: Exploration of metal induced gap states and characteristic properties of Ohmic junction

Ag metallization on the surface of SnO₂ catalyst was performed by the photoreduction method, and its presence was confirmed by the (111), (200), (220), and (311) hkl planes of Ag metal by powder X-ray diffraction technique. Further lattice parameters “a” and “c” of the SnO₂ tetragonal unit cell show prominent changes on metallization. Ultraiolet-visible absorption spectrum of Ag-SnO₂ shows the extended adsorption in the visible region up to almost ~565 nm due to the surface plasmon resonance (SPR) effect. Percentage composition of the elements present in the SnO₂ and Ag-SnO₂ samples were confirmed by the energy-dispersive X-ray analysis and the inductively coupled plasma-atomic emission spectroscopic analysis techniques, and the spherical morphology of these samples were confirmed by the scanning electron microscopy. The photoluminescence technique confirms the reduction of recombination of photogenerated charge carriers by 44% in the case of Ag-SnO₂. The metal-metal oxide contact was found to be Ohmic rather than Schottky. The higher activity of the Ag-SnO₂ nanoparticles are correlated to the SPR effect, metal-induced gap states, inherently created structural defects, the ability of Sn to show multiple oxidation states, variation in the surface oxygen concentration, and also to the Ohmic junction. Synergistic effect between electronic/intrinsic defect energy levels of Ag-SnO₂ photocatalyst with the redox potential of the fast red dye leads to the higher quantum efficiency.