Carbon Electrodes Modified with TiO2/Metal Nanoparticles and Their Application for the Detection of Trinitrotoluene

The preparation of modified, catalytically active, functional carbon electrodes and their application to the electrochemical reduction of trinitrotoluene (TNT) is reported. Modification of the electrodes is performed with composites of nanometer‐sized, mesoporous titanium dioxide, which acts as a support containing inserted/deposited nanoparticles of ruthenium, platinum, or gold. These composites are prepared by a novel sonochemical synthesis using simple and low‐cost precursors. Cyclic voltammetry shows that 2,4,6‐trinitrotoluene can be reduced on thus‐modified carbon‐paper electrodes at potentials of around –0.5 V (vs. Ag/AgCl/Cl^–) in aqueous solutions. Unexpectedly, carbon‐paper electrodes modified with the TiO₂/nano‐Pt composites demonstrate a remarkable electrochemical activity toward the reduction of trinitrotoluene. A significant finding is that the two electrode processes—the reduction of TNT and of oxygen—are quite well separated in potential on the modified carbon‐paper electrodes because of selective electrochemical activity of the TiO₂/nano‐Pt and TiO₂/nano‐Au composites. TiO₂/nano‐Ru composites are found to be much less electrochemically active for the detection of TNT compared to the previous two. It was also established that the titanium dioxide support of TiO₂/nano‐Pt composites plays a specific role for facilitating the TNT‐ and oxygen‐reduction processes.     

Inorganic and Hybrid Organo‐Metal Perovskite Nanostructures: Synthesis,Properties, and Applications

Hybrid perovskite and all‐inorganic perovskite have attracted much attention in recent years owing to their successful use in the photovoltaic field. Usually the perovskite is used in its bulk form, although recently, perovskites' nanocrystalline form has received increased attention. Recent developments in the evolving research field of nanomaterial‐based perovskite are reviewed. Both hybrid organic‐inorganic and all‐inorganic perovskite nanostructures are discussed, as well as approaches to tune the optical properties by controlling the size and shape of perovskite nanostructures. In addition, chemical modifications can change the perovskite nanostructures' band‐gap, similar to their bulk counterpart. Several applications, including light‐emitting diodes, lasers, and detectors, demonstrate the latent potential of perovskite nanostructures.     

A New Method for the Detection of Ignitable Liquid Residues on Arsonist Suspects Hands

In most investigations the investigator focuses on the circumstances under which a fire breaks out. In cases of arson the investigator has another significant task—to link the suspect to the fire and scene of crime. One method is to examine the suspect’s palms for flammable residue consistent with the substance used at the crime scene. In the past several methods were suggested to sample hands. These methods, however, all have a shortcoming: either they suffer from low sensitivity, or they are impractical to use under field conditions. This article presents a new and innovative method with high sensitivity and simple to use in the field. The method is based on passive adsorption using a charcoal strip placed on hands that are placed into a sealed bag for an hour. This is done in the field or in a police station immediately after the arrest of a suspect. The charcoal strip is sent to the laboratory for examination to determine if flammable traces are present. This method was introduced into use in Israel in 2010 and has led to positive results in numerous cases.     

Carbon spherules: synthesis, properties and mechanistic elucidation

Perfect spherical morphology of non-graphitic carbon is prepared by heating mesitylene at 700 °C in a closed cell. It produced mono-dispersed, 2.5 ± 0.05 μm size carbon spherules with a smooth surface, and which have a surface area of 8 m²/g. Morphological and structural analysis of the product is carried out with TEM, HR-SEM, BET surface area, EDAX, C, H, N, S analysis, XRD, HR-TEM, ESR and Raman spectroscopy. The formation of the spherical shape of the carbon bodies is discussed on the basis of the arrangement of the disordered carbon layers.     

Microwave‐Assisted Synthesis of Nanocrystalline MgO and Its Use as a Bacteriocide

Nanocrystalline particles of MgO were synthesized using microwave radiation in an ethylene glycol solution. The antibacterial activities of the MgO nanoparticles were tested by treating Escherichia coli (Gram negative) and Staphylococcus aureus (Gram positive) cultures with 1 mg mL^–1 of the nanoparticles. We have examined the importance of the size effect, pH, and the form of the active MgO species as a bactericidal agent. A clear size dependence of the nanoparticles is observed where the amount of eradicated bacteria was strongly dependent on the particle size.     

Synthesis and characterization of Nb2O5@C core-shell nanorods and Nb2O5 nanorods by reacting Nb(OEt)5 via RAPET (reaction under autogenic pressure at elevated temperatures) technique

The reaction of pentaethoxy niobate, Nb(OEt)₅, at elevated temperature (800 °C) under autogenic pressure provides a chemical route to niobium oxide nanorods coated with amorphous carbon. This synthetic approach yielded nanocrystalline particles of Nb₂O₅@C. As prepared Nb₂O₅@C core-shell nanorods is annealed under air at 500 °C for 3 h (removing the carbon coating) results in neat Nb₂O₅ nanorods. According to the TEM measurements, the Nb₂O₅ crystals exhibit particle sizes between 25 nm and 100 nm, and the Nb₂O₅ crystals display rod-like shapes without any indication of an amorphous character. The optical band gap of the Nb₂O₅ nanorods was determined by diffuse reflectance spectroscopy (DRS) and was found to be 3.8 eV.