No abstract

This article presents a simple and fast method to synthesize metal fluorides such as FeF 2 , CoF 2 , ZnF 2 , LaF 3 , YF 3 , SrF 2 , and metal oxide Fe 2 O 3 having different morphologies. The synthesis is carried out in an ionic liquid solvent using a domestic microwave oven. The products are characterized with the help of an X-ray diffraction method. The different morphologies of the products are studied with the help of a high-resolution transmission electron microscope and a high-resolution scanning electron microscope. The change in the oxidation state of the reactant Fe(III) to the product Fe(II) is confirmed through Mo ¨ssbauer studies. The presence of carbon and its application as a reducing agent is illustrated by Raman spectroscopy.

TiO 2 @C core-shell composite nanoparticles were synthesized by a simple and efficient single-step method in a specially made Swagelok cell at different temperatures. The prepared samples were characterized by XRD, diffuse reflectance-UV-vis, Raman, TEM, HRTEM, and N 2 adsorption-desorption methods. The carbon content in the samples can be varied with reaction time and temperature. It is evident from TEM analysis that the as-prepared samples are core-shell structures of TiO 2 , anatase phase, and C. The diameter of the TiO 2 @C nanoparticles is in the range of 15-35 nm. HRTEM results showed that a few graphitic layers were wrapped on the surface of TiO 2 , and these carbon layers are responsible for suppressing other phase formations of TiO 2 even at high temperature. However, a few percentage points of the rutile phase are observed at high temperature (900 °C), evidenced from Raman analysis. The prepared samples were tested for their photochemical activities for 4-chlorophenol degradation. The sample prepared at 700 °C showed comparable activity for the degradation of 4-chlorophenol with that of Degussa P25. The photobleaching studies of methylene blue were also carried out under sunlight. It was found that the TiO 2 @C samples showed higher photocatalytic activity than Degussa P25.